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  • richardmitnick 9:34 am on September 16, 2021 Permalink | Reply
    Tags: "Where Aliens Could Be Watching Us", , , , , , Exoplanets, ,   

    From Cornell University (US) via Nautilus (US) : “Where Aliens Could Be Watching Us” 

    From Cornell University (US)

    via

    Nautilus (US)

    September 16, 2021
    Lisa Kaltenegger

    1
    A view of the Earth and sun from thousands of miles above our planet, with stars in position to see Earth transiting around the sun brightened and the Milky Way visible on the left. Credit: Open Space/ © American Museum of Natural History-New York City (US).

    More than 1,700 stars could have seen Earth in the past 5,000 years.

    Do you ever feel like someone is watching you? They could be. And I’m not talking about the odd neighbors at the end of your street.

    This summer, at The Carl Sagan Institute (US) at Cornell University and The American Museum of Natural History (US) in NYC, my colleague Jacky Faherty and I identified 1,715 stars in our solar neighborhood that could have seen Earth in the past 5,000 years. In the mesmerizing gravitational dance of the stars, those stars found themselves at just the right place to spot Earth. That’s because our pale blue dot blocks out part of the sun’s light from their view. This is how we find most exoplanets circling other stars. We spot the temporary dimming of their star’s light.

    The perfect cosmic front seat to Earth with its curious beings, is quite rare. But with about the same technology as we have, any nominal, curious aliens on planets circling one of the 1,715 stars could have spotted us. Would they have identified us as intelligent life?

    All of us observe the dynamics of the cosmos every night. Stars rise and set—including our sun—because Earth rotates among the rich stellar tapestry. Our night sky changes throughout the year because Earth moves in orbit around the sun. We only see stars at night when the sun doesn’t outshine them. While circling the sun, we glimpse the brightest stars in the anti-sun direction only. Thus, we see different stars in different seasons.

    If we could watch for thousands of years, we could watch the dynamic dance of the cosmos unfold in our night sky. But alternatively, we can use the newest data from The European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU)’s GAIA mission and computers to fast-forward the time before our eyes, with decades unfolding in mere minutes.

    While we can only see the light of the stars, we already know that more than 4,500 of these stars are not alone. They host extrasolar planets. Several thousand additional signals indicate even more new worlds on our cosmic horizon.

    Astronomers found most of these exoplanets in the last two decades because of a temporary dimming of their stars when a planet, by chance, crossed our line of sight on its journey around its star.

    The planet temporarily blocks out part of the hot star—and its light—from our view. Telescopes on the ground and from space, including NASA’s Kepler and TESS (Transiting Exoplanet Survey Satellite) mission, found thousands of exoplanets by spotting this dimming, which repeats like clockwork.

    The time between dimming tells us how long the planet needs to circle its star. That allows us to figure out how far away an exoplanet wanders from its hot central star. Most known exoplanets are scorching hot gas balls. We can tell when planets orbit closer to a central star than others because they need less time to circle it—we also find those faster than the cooler ones farther away. But about three dozen of these exoplanets are already cool enough. They orbit at the right distance from their stars, where it is not too hot and not too cold. Surface temperatures could allow rivers and oceans to glisten on the surfaces of these planets in this so-called Habitable Zone.

    TRANSIT OF EARTH In this video, scientists at Cornell University and the American Museum of Natural History explain how they have identified stars that have been at just the right place, sometime in the past 5,000 years, to have seen Earth as a transiting exoplanet. Credit: D. Desir National Aeronautics Space Agency (US) / AMNH OpenSpace.

    This vantage point—to see a planet block part of the hot stellar surface from view—is special. The alignment of us and the planet must be just right. Thus, these thousands of known exoplanets are only the tip of the figurative exoplanet iceberg. The ones we can most easily spot hint at the majority waiting to be discovered.

    But what if we change that vantage point? If anyone out there were looking, which stars are just in the right place to spot us?

    Our powers of observation have been boosted by the European Space Agency’s Gaia mission. Launched in 2013, the Gaia spacecraft is mapping the motion stars around the center of our galaxy, the Milky Way.

    The agency aims to survey 1 percent of the galaxy’s 100 billion stars. It has generated the best catalog of stars in our neighborhood within 326 light-years from the sun. Less than 1 percent of the 331,312 catalogued objects —stars, brown dwarfs, and stellar corpses—are at the right place to see Earth as a transiting exoplanet. This special vantage point is held by only those objects in a position close to the plane of Earth’s orbit. Roughly 1,400 stars are at the right place right now to see Earth as a transiting exoplanet.

    But this special vantage point is not forever. It is gained and lost in the precise gravitational dance in our dynamic cosmos. How long does that cosmic front-row seat to Earth transit last? Because the Gaia mission records the motion of the stars, we can spin their movement into the future and trace it back into the past on a computer. It shows us the night sky over thousands of years since civilizations bloomed on Earth and gives us a glimpse of a night sky of the far future, millennia away.

    If we had observed the sky for transiting planets thousands of years earlier or later, we would see different ones. And different ones could find us. We calculated that 1,715 objects in our solar neighborhood could have seen Earth transit since human civilizations started to bloom about 5,000 years ago and kept that special vantage point for hundreds of years. Three hundred and nineteen objects will enter the Earth transit zone in the next 5,000 years.

    Among these 2,034 stars, seven harbor known exoplanets, with three stars’ exoplanets circling in this temperate Habitable Zone. However, the small region around the plane of the Earth’s orbit, where all these stars lie, is crowded. Astronomers usually don’t look for planets there. Generally, it is easier to find exoplanets around stars in non-crowded fields. But now we have a reason: to discover the planets that could also discover us.

    NASA’s Kepler mission stared for more than three years at about 150,000 stars about 1,000 light-years away. These 150,000 stars fit in a small fraction of the sky. Its goal was to estimate how many stars harbor exoplanets. The answer is exciting. Every second star has at least one planet, big or small, and about every fourth star hosts a planet in the Goldilocks Zone. These results provide cautious optimism about our chances of not being the only life in the cosmos. It also means that about 500 exoplanets in the Habitable Zone should be on our list, waiting to be discovered.

    The three systems that host planets in the Habitable Zone in the Earth transit zone are close enough to detect radio waves from Earth. Because radio waves travel at light speed, they have only washed over 75 of the stars on our list so far. These stars are within 100 light-years from Earth—because light had 100 years to travel since Earth first started to leak radio signals.

    Ross 128b, an exoplanet a mere 11 light-years away from us, could have seen Earth block the sun’s light about 3,000 years ago. But it lost this bull’s-eye view about 900 years ago. Another exoplanet, Teegarden’s Star b, which is a bit heavier than Earth, and circles a red sun, is about 12.5 light-years away, and will start to see Earth transit in 29 years. And the fascinating Trappist-1 system, with seven Earth-size planets at 40 light-years distance, will be able to see Earth as a transiting planet but only in about 1,600 years.

    With the launch of the James Webb Space Telescope (JWST) later this year, we will have a big enough telescope to collect light from small, close-by exoplanets that could be like ours.

    A particular combination of oxygen and methane has identified Earth as a living planet for about 2 billion years. That combination of gases is what we will be looking for in the atmosphere of other worlds. This exoplanet exploration will be on the edge of our technological possibility, but it will be possible for the first time. Future technology should be able to characterize exoplanets, not just in transit. But for now, telescopes like the JWST collect only enough light from the atmosphere of close-by transiting worlds to explore them, allowing us to wonder whether nominal curious astronomers on alien worlds might be watching us too.

    Of course, no aliens have visited us yet, and we haven’t found any cosmic messages from them. Is that because we’re unique? Have other civilizations destroyed themselves? Or are they just not interested in us?

    In my Introduction to Astronomy class at Cornell, I ask students whether they would contact or visit an exoplanet that is 5,000 years younger than Earth or 5,000 years older. Without fail, they pick the older planet and its potentially more advanced life. More “advanced” than us. During our discussions, the concept of advanced life invariably rolls back around to us. Would life on Earth qualify as intelligent for anyone watching?

    After all, we’ve been using radio waves for only about 100 years, and so those waves would only have traveled 100 light-years so far. We have set foot on the moon but not farther yet and are only starting to think about interstellar travel. So our interstellar travel resume is awfully thin.

    One thing that an alien astronomer would likely see is our atmosphere. If they had been watching us for a while, they would have seen that we destroyed our ozone layer—but we also managed to fix it. So maybe we would have scored a point on their intelligence scale. Now, of course, they see our atmosphere is becoming concentrated with carbon dioxide and shows no signs of abating yet. But maybe every civilization goes through this, every civilization nearly destroys its habitat before figuring out a way to save themselves from themselves.

    If any aliens are out there watching us from those 2,043 stars in our solar neighborhood, I hope they’re also rooting for us.

    Science paper:
    Nature

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Once called “the first American university” by educational historian Frederick Rudolph, Cornell University represents a distinctive mix of eminent scholarship and democratic ideals. Adding practical subjects to the classics and admitting qualified students regardless of nationality, race, social circumstance, gender, or religion was quite a departure when Cornell was founded in 1865.

    Today’s Cornell reflects this heritage of egalitarian excellence. It is home to the nation’s first colleges devoted to hotel administration, industrial and labor relations, and veterinary medicine. Both a private university and the land-grant institution of New York State, Cornell University is the most educationally diverse member of the Ivy League.

    On the Ithaca campus alone nearly 20,000 students representing every state and 120 countries choose from among 4,000 courses in 11 undergraduate, graduate, and professional schools. Many undergraduates participate in a wide range of interdisciplinary programs, play meaningful roles in original research, and study in Cornell programs in Washington, New York City, and the world over.

    Cornell University (US) is a private, statutory, Ivy League and land-grant research university in Ithaca, New York. Founded in 1865 by Ezra Cornell and Andrew Dickson White, the university was intended to teach and make contributions in all fields of knowledge—from the classics to the sciences, and from the theoretical to the applied. These ideals, unconventional for the time, are captured in Cornell’s founding principle, a popular 1868 quotation from founder Ezra Cornell: “I would found an institution where any person can find instruction in any study.”

    The university is broadly organized into seven undergraduate colleges and seven graduate divisions at its main Ithaca campus, with each college and division defining its specific admission standards and academic programs in near autonomy. The university also administers two satellite medical campuses, one in New York City and one in Education City, Qatar, and Jacobs Technion-Cornell Institute(US) in New York City, a graduate program that incorporates technology, business, and creative thinking. The program moved from Google’s Chelsea Building in New York City to its permanent campus on Roosevelt Island in September 2017.

    Cornell is one of the few private land grant universities in the United States. Of its seven undergraduate colleges, three are state-supported statutory or contract colleges through the SUNY – The State University of New York (US) system, including its Agricultural and Human Ecology colleges as well as its Industrial Labor Relations school. Of Cornell’s graduate schools, only the veterinary college is state-supported. As a land grant college, Cornell operates a cooperative extension outreach program in every county of New York and receives annual funding from the State of New York for certain educational missions. The Cornell University Ithaca Campus comprises 745 acres, but is much larger when the Cornell Botanic Gardens (more than 4,300 acres) and the numerous university-owned lands in New York City are considered.

    Alumni and affiliates of Cornell have reached many notable and influential positions in politics, media, and science. As of January 2021, 61 Nobel laureates, four Turing Award winners and one Fields Medalist have been affiliated with Cornell. Cornell counts more than 250,000 living alumni, and its former and present faculty and alumni include 34 Marshall Scholars, 33 Rhodes Scholars, 29 Truman Scholars, 7 Gates Scholars, 55 Olympic Medalists, 10 current Fortune 500 CEOs, and 35 billionaire alumni. Since its founding, Cornell has been a co-educational, non-sectarian institution where admission has not been restricted by religion or race. The student body consists of more than 15,000 undergraduate and 9,000 graduate students from all 50 American states and 119 countries.

    History

    Cornell University was founded on April 27, 1865; the New York State (NYS) Senate authorized the university as the state’s land grant institution. Senator Ezra Cornell offered his farm in Ithaca, New York, as a site and $500,000 of his personal fortune as an initial endowment. Fellow senator and educator Andrew Dickson White agreed to be the first president. During the next three years, White oversaw the construction of the first two buildings and traveled to attract students and faculty. The university was inaugurated on October 7, 1868, and 412 men were enrolled the next day.

    Cornell developed as a technologically innovative institution, applying its research to its own campus and to outreach efforts. For example, in 1883 it was one of the first university campuses to use electricity from a water-powered dynamo to light the grounds. Since 1894, Cornell has included colleges that are state funded and fulfill statutory requirements; it has also administered research and extension activities that have been jointly funded by state and federal matching programs.

    Cornell has had active alumni since its earliest classes. It was one of the first universities to include alumni-elected representatives on its Board of Trustees. Cornell was also among the Ivies that had heightened student activism during the 1960s related to cultural issues; civil rights; and opposition to the Vietnam War, with protests and occupations resulting in the resignation of Cornell’s president and the restructuring of university governance. Today the university has more than 4,000 courses. Cornell is also known for the Residential Club Fire of 1967, a fire in the Residential Club building that killed eight students and one professor.

    Since 2000, Cornell has been expanding its international programs. In 2004, the university opened the Weill Cornell Medical College in Qatar. It has partnerships with institutions in India, Singapore, and the People’s Republic of China. Former president Jeffrey S. Lehman described the university, with its high international profile, a “transnational university”. On March 9, 2004, Cornell and Stanford University(US) laid the cornerstone for a new ‘Bridging the Rift Center’ to be built and jointly operated for education on the Israel–Jordan border.

    Research

    Cornell, a research university, is ranked fourth in the world in producing the largest number of graduates who go on to pursue PhDs in engineering or the natural sciences at American institutions, and fifth in the world in producing graduates who pursue PhDs at American institutions in any field. Research is a central element of the university’s mission; in 2009 Cornell spent $671 million on science and engineering research and development, the 16th highest in the United States. Cornell is classified among “R1: Doctoral Universities – Very high research activity”.

    For the 2016–17 fiscal year, the university spent $984.5 million on research. Federal sources constitute the largest source of research funding, with total federal investment of $438.2 million. The agencies contributing the largest share of that investment are the Department of Health and Human Services and the National Science Foundation(US), accounting for 49.6% and 24.4% of all federal investment, respectively. Cornell was on the top-ten list of U.S. universities receiving the most patents in 2003, and was one of the nation’s top five institutions in forming start-up companies. In 2004–05, Cornell received 200 invention disclosures; filed 203 U.S. patent applications; completed 77 commercial license agreements; and distributed royalties of more than $4.1 million to Cornell units and inventors.

    Since 1962, Cornell has been involved in unmanned missions to Mars. In the 21st century, Cornell had a hand in the Mars Exploration Rover Mission. Cornell’s Steve Squyres, Principal Investigator for the Athena Science Payload, led the selection of the landing zones and requested data collection features for the Spirit and Opportunity rovers. NASA-JPL/Caltech(US) engineers took those requests and designed the rovers to meet them. The rovers, both of which have operated long past their original life expectancies, are responsible for the discoveries that were awarded 2004 Breakthrough of the Year honors by Science. Control of the Mars rovers has shifted between National Aeronautics and Space Administration(US)’s JPL-Caltech (US) and Cornell’s Space Sciences Building.

    Further, Cornell researchers discovered the rings around the planet Uranus, and Cornell built and operated the telescope at Arecibo Observatory located in Arecibo, Puerto Rico(US) until 2011, when they transferred the operations to SRI International, the Universities Space Research Association (US) and the Metropolitan University of Puerto Rico [Universidad Metropolitana de Puerto Rico](US).

    The Automotive Crash Injury Research Project was begun in 1952. It pioneered the use of crash testing, originally using corpses rather than dummies. The project discovered that improved door locks; energy-absorbing steering wheels; padded dashboards; and seat belts could prevent an extraordinary percentage of injuries.

    In the early 1980s, Cornell deployed the first IBM 3090-400VF and coupled two IBM 3090-600E systems to investigate coarse-grained parallel computing. In 1984, the National Science Foundation began work on establishing five new supercomputer centers, including the Cornell Center for Advanced Computing, to provide high-speed computing resources for research within the United States. As an National Science Foundation (US) center, Cornell deployed the first IBM Scalable Parallel supercomputer.

    In the 1990s, Cornell developed scheduling software and deployed the first supercomputer built by Dell. Most recently, Cornell deployed Red Cloud, one of the first cloud computing services designed specifically for research. Today, the center is a partner on the National Science Foundation XSEDE-Extreme Science Engineering Discovery Environment supercomputing program, providing coordination for XSEDE architecture and design, systems reliability testing, and online training using the Cornell Virtual Workshop learning platform.

    Cornell scientists have researched the fundamental particles of nature for more than 70 years. Cornell physicists, such as Hans Bethe, contributed not only to the foundations of nuclear physics but also participated in the Manhattan Project. In the 1930s, Cornell built the second cyclotron in the United States. In the 1950s, Cornell physicists became the first to study synchrotron radiation.

    During the 1990s, the Cornell Electron Storage Ring, located beneath Alumni Field, was the world’s highest-luminosity electron-positron collider. After building the synchrotron at Cornell, Robert R. Wilson took a leave of absence to become the founding director of DOE’s Fermi National Accelerator Laboratory(US), which involved designing and building the largest accelerator in the United States.

    Cornell’s accelerator and high-energy physics groups are involved in the design of the proposed ILC-International Linear Collider(JP) and plan to participate in its construction and operation. The International Linear Collider(JP), to be completed in the late 2010s, will complement the CERN Large Hadron Collider(CH) and shed light on questions such as the identity of dark matter and the existence of extra dimensions.

    As part of its research work, Cornell has established several research collaborations with universities around the globe. For example, a partnership with the University of Sussex(UK) (including the Institute of Development Studies at Sussex) allows research and teaching collaboration between the two institutions.

     
  • richardmitnick 8:47 am on June 11, 2021 Permalink | Reply
    Tags: "'Earth Cousins' Are New Targets for Planetary Materials Research", A key to understanding atmospheric composition is understanding exchanges between the planet’s atmosphere and interior during planet formation and evolution., About 1000 sub-Neptune exoplanets (radius of 1.6–3.5 R⨁) have been confirmed., Are the processes that generate planetary habitability in our solar system common or rare elsewhere?, , , , , , Evidence indicates that the known sub-Neptunes are mostly magma by mass and mostly atmosphere by volume ., Exoplanets, Four classes of exoplanets, On exoplanets the observable is the atmosphere., , The mass fraction of water on Europa; Ceres; and the parent bodies of carbonaceous chondrite meteorites is some 50–3000 times greater than on Earth.   

    From Eos : “‘Earth Cousins’ Are New Targets for Planetary Materials Research” 

    From AGU
    Eos news bloc

    From Eos

    6.10.21
    Edwin Kite
    kite@uchicago.edu

    Laura Kreidberg
    Laura Schaefer
    Razvan Caracas
    Marc Hirschmann

    “Cousin” worlds—slightly bigger or slightly hotter than Earth—can help us understand planetary habitability, but we need more lab and numerical experiments to make the most of this opportunity.

    1
    Exoplanet LHS-3844 b, about 49 light-years away from Earth, is slightly larger than Earth, but extreme temperature differences between its light and dark sides (a clue that it is not likely to have much of an atmosphere) make it an unlikely place to look for life. Credit: R. Hurt (Caltech NASA Infrared Processing and Analysis Center (US)) National Aeronautics and Space Administration (US)/JPL-Caltech (US)

    Are the processes that generate planetary habitability in our solar system common or rare elsewhere? Answering this fundamental question poses an enormous challenge.

    For example, observing Earth-analogue exoplanets—that is, Earth-sized planets orbiting within the habitable zone of their host stars—is difficult today and will remain so even with the next-generation James Webb Space Telescope (JWST) and large-aperture ground-based telescopes.

    In coming years, it will be much easier to gather data on—and to test hypotheses about the processes that generate and sustain habitability using—“Earth cousins.” These small-radius exoplanets lack solar system analogues but are more accessible to observation because they are slightly bigger or slightly hotter than Earth.

    Here we discuss four classes of exoplanets and the investigations of planetary materials that are needed to understand them (Figure 1). Such efforts will help us better understand planets in general and Earth-like worlds in particular.

    2
    Fig. 1. Shown here are four common exoplanet classes that are relatively easy to characterize using observations from existing telescopes (or telescopes that will be deployed soon) and that have no solar system analogue. Hypothetical cross sections for each planet type show interfaces that can be investigated using new laboratory and numerical experiments. CO2 = carbon dioxide, Fe = iron, H2O = water, Na = sodium.

    What’s in the Air?

    On exoplanets the observable is the atmosphere. Atmospheres are now routinely characterized for Jupiter-sized exoplanets. And scientists are acquiring constraints for various atmospheric properties of smaller worlds (those with a radius R less than 3.5 Earth radii R⨁), which are very abundant [e.g., Benneke et al., 2019*; Kreidberg et al., 2019]. Soon, observatories applying existing methods and new techniques such as high-resolution cross-correlation spectroscopy will reveal even more information.

    *All citations in References below.

    For these smaller worlds, as for Earth, a key to understanding atmospheric composition is understanding exchanges between the planet’s atmosphere and interior during planet formation and evolution. This exchange often occurs at interfaces (i.e., surfaces) between volatile atmospheres and condensed (liquid or solid) silicate materials. For many small exoplanets, these interfaces exhibit pressure-temperature-composition (P–T–X) regimes very different from Earth’s and that have been little explored in laboratory and numerical experiments. To use exoplanet data to interpret the origin and evolution of these strange new worlds, we need new experiments exploring the relevant planetary materials and conditions.

    Studying Earth cousin exoplanets can help us probe the delivery and distribution of life-essential volatile species—chemical elements and compounds like water vapor and carbon-containing molecules, for example, that form atmospheres and oceans, regulate climate, and (on Earth) make up the biosphere. Measuring abundances of these volatiles on cousin worlds that orbit closer to their star than the habitable zone is relatively easy to do. These measurements are fundamental to understanding habitability because volatile species abundances on Earth cousin exoplanets will help us understand volatile delivery and loss processes operating within habitable zones.

    For example, rocky planets now within habitable zones around red dwarf stars must have spent more than 100 million years earlier in their existence under conditions exceeding the runaway greenhouse limit, suggesting surface temperatures hot enough to melt silicate rock into a magma ocean. So whether these worlds are habitable today depends on the amount of life-essential volatile elements supplied from sources farther from the star [e.g., Tian and Ida, 2015], as well as on how well these elements are retained during and after the magma ocean phase.

    Volatiles constitute a small fraction of a rocky planet’s mass, and quantifying their abundance is inherently hard. However, different types of Earth cousin exoplanets offer natural solutions that can ease volatile detection. For example, on planets known as sub-Neptunes, the spectroscopic fingerprint of volatiles could be easier to detect because of their mixing with lower–molecular weight atmospheric species like hydrogen and helium. These lightweight species contribute to more puffed-up (expanded) and thus more detectable atmospheres. Hot, rocky exoplanets could “bake out” volatiles from their interiors while also heating and puffing up the atmosphere, which would make spectral features more visible. Disintegrating rocky planets may disperse their volatiles into large, and therefore more observable, comet-like tails.

    Let’s look at each of these examples further.

    Unexpected Sub-Neptunes

    About 1000 sub-Neptune exoplanets (radius of 1.6–3.5 R⨁) have been confirmed. These planets, which are statistically about as common as stars, blur the boundary between terrestrial planets and gas giants.

    2
    A warm, Neptune-sized exoplanet orbits the red dwarf star GJ 3470. Intense radiation from the star heats the planet’s atmosphere, causing large amounts of hydrogen gas to stream off into space. Credit: D. Player (Space Telescope Science Institute (US)) NASA/European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU).

    Strong, albeit indirect, evidence indicates that the known sub-Neptunes are mostly magma by mass and mostly atmosphere by volume (for a review, see Bean et al. [2021]). This evidence implies that an interface occurs, at pressures typically between 10 and 300 kilobars, between the magma and the molecular hydrogen (H2)-dominated atmosphere on these planets. Interactions at and exchanges across this interface dictate the chemistry and puffiness of the atmosphere. For example, water can form and become a significant fraction of the atmosphere, leading to more chemically complex atmospheres.

    Improved molecular dynamics calculations are needed to quantify the solubilities of gases and gas mixtures in realistic magma ocean compositions (and in iron alloys composing planetary cores, which can also serve as reservoirs for volatiles) over a wider range of pressures and temperatures than we have studied until now. These calculations should be backed up by laboratory investigations of such materials using high-pressure instrumentation like diamond anvil cells. These calculations and experiments will provide data to help determine the equation of state (the relationship among pressure, volume, and temperature), transport properties, and chemical kinetics of H2-magma mixtures as they might exist on these exoplanets.

    3
    Fig. 2. Ranges of plausible conditions at the interfaces between silicate surface rocks and volatile atmospheres on different types of worlds are indicated in this pressure–temperature (P-T) diagram. Conditions on Earth, as well as other relevant conditions (critical points are the highest P-T points where materials coexist in gaseous and liquid states, and triple points are where three phases coexist), are also indicated. Mg2SiO4 = forsterite, an igneous mineral that is abundant in Earth’s mantle.

    Because sub-Neptunes are so numerous, we cannot claim to understand the exoplanet mass-radius relationship in general (in effect, the equation of state of planets in the galaxy) without understanding interactions between H2 and magma on sub-Neptunes. To understand the extent of mixing between H2, silicates, and iron alloy during sub-Neptune assembly and evolution, we need more simulations of giant impacts during planet formation [e.g., Davies et al., 2020], as well as improved knowledge of convective processes on these planets. Within the P-T-X regimes of sub-Neptunes, full miscibility between silicates and H2 becomes important (Figure 2).

    Beyond shedding light on the chemistry and magma-atmosphere interactions on these exoplanets, new experiments may also help reveal the potential for and drivers of magnetic fields on sub-Neptunes. Such fields might be generated within both the atmosphere and the magma.

    Hot and Rocky

    From statistical studies, we know that most stars are orbited by at least one roughly Earth-sized planet (radius of 0.75–1.6 R⨁) that is irradiated more strongly than our Sun’s innermost planet, Mercury. These hot, rocky exoplanets, of which about a thousand have been confirmed, experience high fluxes of atmosphere-stripping ultraviolet photons and stellar wind. Whether they retain life-essential elements like nitrogen, carbon, and sulfur is unknown.

    On these hot, rocky exoplanets—and potentially on Venus as well—atmosphere-rock or atmosphere-magma interactions at temperatures too high for liquid water will be important in determining atmospheric composition and survival. But these interactions have been only sparingly investigated [Zolotov, 2018].

    Many metamorphic and melting reactions between water and silicates under kilopascal to tens-of-gigapascal pressures are already known from experiments or are tractable using thermodynamic models. However, less well understood processes may occur in planets where silicate compositions and proportions are different than they are on Earth, meaning that exotic rock phases may be important. Innovative experiments and modeling that consider plausible exotic conditions will help us better understand these planets. Moreover, we need to conduct vaporization experiments to probe whether moderately volatile elements are lost fast enough from hot, rocky planets to form a refractory lag and reset surface spectra.

    Exotic Water Worlds?

    Water makes up about 0.01% of Earth’s mass. In contrast, the mass fraction of water on Europa, Ceres, and the parent bodies of carbonaceous chondrite meteorites is some 50–3,000 times greater than on Earth. Theory predicts that such water-rich worlds will be common not only in habitable zones around other stars but even in closer orbits as well. The JWST will be able to confirm or refute this theory [Greene et al., 2016].

    If we could descend through the volatile-rich outer envelope of a water world, we might find habitable temperatures at shallow depths [Kite and Ford, 2018]. Some habitable layers may be cloaked beneath H2. Farther down, as the atmospheric pressure reaches 10 or more kilobars, we might encounter silicate-volatile interfaces featuring supercritical fluids [e.g., Nisr et al., 2020] and conditions under which water can be fully miscible with silicates [Ni et al., 2017].

    We still need answers to several key questions about these worlds. What are the equilibria and rates of gas production and uptake for rock-volatile interfaces at water world “seafloors”? Can they sustain a habitable climate? With no land, and thus no continental weathering, can seafloor reactions supply life-essential nutrients? Do high pressures and stratification suppress the tectonics and volcanism that accelerate interior-atmosphere exchange [Kite and Ford, 2018]?

    As for the deep interiors of Titan and Ganymede in our own solar system, important open questions include the role of clathrates (compounds like methane hydrates in which one chemical component is enclosed within a molecular “cage”) and the solubility and transport of salts through high-pressure ice layers.

    Experiments are needed to understand processes at water world seafloors. Metamorphic petrologists are already experienced with the likely pressure-temperature conditions in these environments, and exoplanetary studies could benefit from their expertise. Relative to rock compositions on Earth, we should expect exotic petrologies on water worlds—for example, worlds that are as sodium rich as chondritic meteorites. Knowledge gained through this work would not only shed light on exoplanetary habitability but also open new paths of research into studying exotic thermochemical environments in our solar system.

    Magma Seas and Planet Disintegration

    Some 100 confirmed rocky exoplanets are so close to their stars that they have surface seas of very low viscosity magma. The chemical evolution of these long-lived magma seas is affected by fractional vaporization, in which more volatile materials rise into the atmosphere and can be relocated to the planet’s dark side or lost to space [e.g., Léger et al., 2011; Norris and Wood, 2017], and perhaps by exchange with underlying solid rock.

    Magma planets usually have low albedos, reflecting relatively little light from their surfaces. However, some of these planets appear to be highly reflective, perhaps because their surfaces are distilled into a kind of ceramic rich in calcium and aluminum. One magma planet’s thermal signature has been observed to vary from month to month by a factor of 2 [Demory et al., 2016], implying that it undergoes a global energy balance change more than 10,000 times greater than that from anthropogenic climate change on Earth. Such large swings suggest that fast magma ocean–atmosphere feedbacks operate on the planet.

    To learn more about the chemical evolution and physical properties of exoplanet magma seas, we need experiments like those used to study early-stage planet formation, which can reveal information about silicate vaporization and kinetics under the temperatures (1,500–3,000 K) and pressures (10−5 to 100 bars) of magma planet surfaces.

    Exoplanets and exoplanetesimals that stray too close to their stars are destroyed—about five such cases have been confirmed. These disintegrating planets give geoscientists direct views of exoplanetary silicates because the debris tails can be millions of kilometers long [van Lieshout and Rappaport, 2018]. For disintegrating planets that orbit white dwarf stars, the debris can form a gas disk whose composition can be reconstructed [e.g., Doyle et al., 2019].

    To better read the signals of time-variable disintegration, we need more understanding of how silicate vapor in planetary outflows condenses and nucleates, as well as of fractionation processes at and above disintegrating planets’ surfaces that may cause observed compositions in debris to diverge from the bulk planet compositions.

    Getting to Know the Cousins

    In the near future, new observatories like JWST [above] and the European Space Agency’s Atmospheric Remote-sensing Infrared Exoplanet Large-survey (ARIEL, planned for launch in 2029) will provide new data.

    When they do, and even now before they come online, investigating Earth cousins will illuminate the processes underpinning habitability in our galaxy and reveal much that is relevant for understanding Earth twins.

    From sub-Neptunes, for example, we can learn about volatile delivery processes. From hot, rocky planets, we can learn about atmosphere-interior exchange and atmospheric loss processes. From water worlds, we can learn about nutrient supplies in exoplanetary oceans and the potential habitability of these exotic environments. From disintegrating planets, we can learn about the interior composition of rocky bodies.

    Laboratory studies of processes occurring on these worlds require only repurposing and enhancing existing experimental facilities, rather than investing in entire new facilities. From a practical standpoint, the scientific rewards of studying Earth cousins are low-hanging fruit.

    References:

    Bean, J., et al. (2021), The nature and origins of sub-Neptune size planets, J. Geophys. Res. Planets, 126(1), e2020JE006639, https://doi.org/10.1029/2020JE006639.

    Benneke, B., et al. (2019), A sub-Neptune exoplanet with a low-metallicity methane-depleted atmosphere and Mie-scattering clouds, Nat. Astron., 3, 813–821, https://doi.org/10.1038/s41550-019-0800-5.

    Davies, E. J., et al. (2020), Silicate melting and vaporization during rocky planet formation, J. Geophys. Res. Planets, 125(1), e2019JE006227, https://doi.org/10.1029/2019JE006227.

    Demory, B.-O., et al. (2016), Variability in the super-Earth 55 Cnc e, Mon. Notices R. Astron. Soc., 455, 2,018–2,027, https://doi.org/10.1093/mnras/stv2239.

    Doyle, A., et al. (2019), Oxygen fugacities of extrasolar rocks: Evidence for an Earth-like geochemistry of exoplanets, Science, 366, 356–358, https://doi.org/10.1126/science.aax3901.

    Greene, T. P., et al. (2016), Characterizing transiting exoplanet atmospheres with JWST, Astrophys. J., 817, 17, https://doi.org/10.3847/0004-637X/817/1/17.

    Kite, E. S., and E. Ford (2018), Habitability of exoplanet waterworlds, Astrophys. J., 864, 75, https://doi.org/10.3847/1538-4357/aad6e0.

    Kreidberg, L., et al. (2019), Absence of a thick atmosphere on the terrestrial exoplanet LHS 3844b, Nature, 573, 87–90, https://doi.org/10.1038/s41586-019-1497-4.

    Léger, A., et al. (2011), The extreme physical properties of the CoRoT-7b super-Earth, Icarus, 213, 1–11, https://doi.org/10.1016/j.icarus.2011.02.004.

    Ni, H., et al. (2017), Supercritical fluids at subduction zones: Evidence, formation condition, and physicochemical properties, Earth Sci. Rev., 167, 62–71, https://doi.org/10.1016/j.earscirev.2017.02.006.

    Nisr, C., et al. (2020), Large H2O solubility in dense silica and its implications for the interiors of water-rich planets, Proc. Natl. Acad. Sci. U. S. A., 117, 9747, https://doi.org/10.1073/pnas.1917448117.

    Norris, C. A., and B. J. Wood (2017), Earth’s volatile contents established by melting and vaporization, Nature, 549, 507–510, https://doi.org/10.1038/nature23645.

    Tian, F., and S. Ida (2015), Water contents of Earth-mass planets around M dwarfs, Nat. Geosci., 8, 177–180, https://doi.org/10.1038/ngeo2372.

    van Lieshout, R., and S. A. Rappaport (2018), Disintegrating rocky exoplanets, in Handbook of Exoplanets, pp. 1,527–1,544, Springer, Cham, Switzerland, https://doi.org/10.1007/978-3-319-55333-7_15.

    Zolotov, M. (2018), Chemical weathering on Venus, in Oxford Research Encyclopedia of Planetary Science, edited by P. Read et al., Oxford Univ. Press, Oxford, U.K., https://doi.org/10.1093/acrefore/9780190647926.013.146.

    See the full article here .

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    Eos is the leading source for trustworthy news and perspectives about the Earth and space sciences and their impact. Its namesake is Eos, the Greek goddess of the dawn, who represents the light shed on understanding our planet and its environment in space by the Earth and space sciences.

     
  • richardmitnick 8:06 pm on June 10, 2021 Permalink | Reply
    Tags: , , , Citizen Scientists Discover Two Gaseous Planets around a Bright Sun-like Star", , Exoplanets, , Two gaseous planets orbit the bright star HD 152843.   

    From NASA Goddard Space Flight Center (US) : “Citizen Scientists Discover Two Gaseous Planets around a Bright Sun-like Star” 

    NASA Goddard Banner

    From NASA Goddard Space Flight Center (US)

    Jun 10, 2021

    Elizabeth Landau
    elandau@nasa.gov
    NASA Headquarters

    Media Contact
    Claire Andreoli
    claire.andreoli@nasa.gov
    NASA’s Goddard Space Flight Center, Greenbelt, Md.
    (301) 286-1940

    At night, seven-year-old Miguel likes talking to his father Cesar Rubio about planets and stars. “I try to nurture that,” says Rubio, a machinist in Pomona, California, who makes parts for mining and power generation equipment.

    1
    In this artist’s rendering, two gaseous planets orbit the bright star HD 152843. These planets were discovered through the citizen science project Planet Hunters TESS, in collaboration with professional scientists.
    Credits: NASA/Scott Wiessinger.

    Now, the boy’s father can claim he helped discover planets, too. He is one of thousands of volunteers participating in Planet Hunters TESS, a NASA-funded citizen science project that looks for evidence of planets beyond our solar system, or exoplanets. Citizen science is a way for members of the public to collaborate with scientists. More than 29,000 people worldwide have joined the Planet Hunters TESS effort to help scientists find exoplanets.

    2
    Cesar Rubio and his son Miguel enjoy talking about space together.
    Credits: Cesar Rubio

    Planet Hunters TESS has now announced the discovery of two exoplanets in a study published online in MNRAS, listing Rubio and more than a dozen other citizen scientists as co-authors.

    These exotic worlds orbit a star called HD 152843, located about 352 light-years away. This star is about the same mass as the Sun, but almost 1.5 times bigger and slightly brighter.

    Planet b, about the size of Neptune, is about 3.4 times bigger than Earth, and completes an orbit around its star in about 12 days. Planet c, the outer planet, is about 5.8 times bigger than Earth, making it a “sub-Saturn,” and its orbital period is somewhere between 19 and 35 days. In our own solar system, both of these planets would be well within the orbit of Mercury, which is about 88 days.

    “Studying them together, both of them at the same time, is really interesting to constrain theories of how planets both form and evolve over time,” said Nora Eisner, a doctoral student in astrophysics at the University of Oxford in the United Kingdom and lead author of the study.

    TESS stands for Transiting Exoplanet Survey Satellite, a NASA spacecraft that launched in April 2018. The TESS team has used data from the observatory to identify more than 100 exoplanets and over 2,600 candidates that await confirmation.

    National Aeronautics Space Agency (US)/Massachusetts Institute of Technology (US) TESS

    Additional partners include Northrop Grumman, based in Falls Church, Virginia; NASA’s Ames Research Center in California’s Silicon Valley; the Center for Astrophysics – Harvard and Smithsonian; MIT Lincoln Laboratory; and the NASA Space Telescope Science Institute (US) in Baltimore.

    Planet Hunters TESS, operated through the Zooniverse website, began in December 2018, shortly after the first TESS data became publicly available. Volunteers look at graphs showing the brightness of different stars over time. They note which of those plots show a brief dip in the star’s brightness and then an upward swing to the original level. This can happen when a planet crosses the face of its star, blocking out a tiny bit of light — an event called a “transit.”

    The Planet Hunters project shares each brightness plot, called a “light curve,” with 15 volunteers. In the background of the website, an algorithm collects all of the volunteers’ submissions and picks out light curves that multiple volunteers have flagged. Eisner and colleagues then look at the highest-ranked light curves and determine which ones would be good for scientific follow-up.

    Even in an era of sophisticated computing techniques like machine learning, having a large group of volunteers looking through telescope data is a big help to researchers. Since researchers can’t perfectly train computers to identify the signatures of potential planets, the human eye is still valuable. “That’s why a lot of exoplanet candidates are missed, and why citizen science is great,” Eisner said.

    In the case of HD 152843, citizen scientists looked at a plot showing its brightness during one month of TESS observations. The light curve showed three distinct dips, meaning at least one planet could be orbiting the star. All 15 citizen scientists who looked at this light curve flagged at least two transits, and some flagged the light curve on the Planet Hunters TESS online discussion forum.

    Then, scientists took a closer look. By comparing the data to their models, they estimated that two transits came from the inner planet and the other came from a second, outer planet.

    To make sure the transit signals came from planets and not some other source, such as stars that eclipse each other, passing asteroids, or the movements of TESS itself, scientists needed to look at the star with a different method. They used an instrument called HARPS-N (the High Accuracy Radial velocity Planet Searcher for the Northern hemisphere) at the Telescopio Nazionale Galileo in La Palma, Spain, as well as EXPRES (the Extreme Precision Spectrometer), an instrument at Lowell Observatory in Flagstaff, Arizona.

    Both HARPS and EXPRES look for the presence of planets by examining whether starlight is “wobbling” due to planets orbiting their star. This technique, called the radial velocity method, allows scientists to estimate the mass of a distant planet, too.

    While scientists could not get a signal clear enough to pinpoint the planets’ masses, they got enough radial velocity data to make mass estimates — about 12 times the mass of Earth for planet b and about 28 times the mass of Earth for planet c. Their measurements validate that signals that indicate the presence of planets; more data are needed for confirmation of their masses. Scientists continue to observe the planetary system with HARPS-N and hope to have more information about the planets soon.

    Researchers may soon have high-tech tools to see if these planets have atmospheres and what gases are present in them. NASA’s James Webb Space Telescope, launching later this year, will be able to look at what kinds of molecules make up the atmospheres of planets like those in this system, especially the larger outer planet.

    The HD 152843 planets are far too hot and gaseous to support life as we know it, but they are valuable to study as scientists learn about the range of possible planets in our galaxy.

    “We’re taking baby steps towards the direction of finding an Earth-like planet and studying its atmosphere, and continue to push the boundaries of what we can see,” Eisner said.

    The citizen scientists who classified the HD 152843 light curve as a possible source of transiting planets, in addition to three Planet Hunters discussion forum moderators, were invited to have their names listed as co-authors on the study announcing the discovery of these planets.

    One of these citizen scientists is Alexander Hubert, a college student concentrating in mathematics and Latin in Würzburg, Germany, with plans to become a secondary school teacher. So far, he has classified more than 10,000 light curves through Planet Hunters TESS.

    “I regret sometimes that in our times, we have to constrain ourselves to one, maybe two subjects, like for me, Latin and mathematics,” Hubert said. “I’m really grateful that I have the opportunity on Zooniverse to participate in something different.”

    Elisabeth Baeten of Leuven, Belgium, another co-author, works in the administration of reinsurance, and says classifying light curves on Planet Hunters TESS is “relaxing.” Interested in astronomy since childhood, she was one of the original volunteers of Galaxy Zoo, an astronomy citizen science project that started in 2007. Galaxy Zoo invited participants to classify the shapes of distant galaxies.

    While Baeten has been part of more than a dozen published studies through Zooniverse projects, the new study is Rubio’s first scientific publication. Astronomy has been a life-long interest, and something he can now share with his son. The two sometimes look at the Planet Hunters TESS website together.

    “I feel that I’m contributing, even if it’s only like a small part,” Rubio said. “Especially scientific research, it’s satisfying for me.”

    NASA has a wide variety of citizen science collaborations across topics ranging from Earth science to the Sun to the wider universe. Anyone in the world can participate. Check out the latest opportunities at http://www.science.nasa.gov/citizenscience.

    See the full article here.


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    Please help promote STEM in your local schools.


    Stem Education Coalition


    NASA/Goddard Campus

    NASA’s Goddard Space Flight Center, Greenbelt, MD (US) is home to the nation’s largest organization of combined scientists, engineers and technologists that build spacecraft, instruments and new technology to study the Earth, the sun, our solar system, and the universe.

    Named for American rocketry pioneer Dr. Robert H. Goddard, the center was established in 1959 as NASA’s first space flight complex. Goddard and its several facilities are critical in carrying out NASA’s missions of space exploration and scientific discovery.

    GSFC also operates two spaceflight tracking and data acquisition networks (the NASA Deep Space Network(US) and the Near Earth Network); develops and maintains advanced space and Earth science data information systems, and develops satellite systems for the National Oceanic and Atmospheric Administration(US) .

    GSFC manages operations for many NASA and international missions including the NASA/ESA Hubble Space Telescope; the Explorers Program; the Discovery Program; the Earth Observing System; INTEGRAL; MAVEN; OSIRIS-REx; the Solar and Heliospheric Observatory ; the Solar Dynamics Observatory; Tracking and Data Relay Satellite System ; Fermi; and Swift. Past missions managed by GSFC include the Rossi X-ray Timing Explorer (RXTE), Compton Gamma Ray Observatory, SMM, COBE, IUE, and ROSAT. Typically, unmanned Earth observation missions and observatories in Earth orbit are managed by GSFC, while unmanned planetary missions are managed by the Jet Propulsion Laboratory (JPL) in Pasadena, California(US).

    Goddard is one of four centers built by NASA since its founding on July 29, 1958. It is NASA’s first, and oldest, space center. Its original charter was to perform five major functions on behalf of NASA: technology development and fabrication; planning; scientific research; technical operations; and project management. The center is organized into several directorates, each charged with one of these key functions.

    Until May 1, 1959, NASA’s presence in Greenbelt, MD was known as the Beltsville Space Center. It was then renamed the Goddard Space Flight Center (GSFC), after Robert H. Goddard. Its first 157 employees transferred from the United States Navy’s Project Vanguard missile program, but continued their work at the Naval Research Laboratory in Washington, D.C., while the center was under construction.

    Goddard Space Flight Center contributed to Project Mercury, America’s first manned space flight program. The Center assumed a lead role for the project in its early days and managed the first 250 employees involved in the effort, who were stationed at Langley Research Center in Hampton, Virginia. However, the size and scope of Project Mercury soon prompted NASA to build a new Manned Spacecraft Center, now the Johnson Space Center, in Houston, Texas. Project Mercury’s personnel and activities were transferred there in 1961.

    The Goddard network tracked many early manned and unmanned spacecraft.

    Goddard Space Flight Center remained involved in the manned space flight program, providing computer support and radar tracking of flights through a worldwide network of ground stations called the Spacecraft Tracking and Data Acquisition Network (STDN). However, the Center focused primarily on designing unmanned satellites and spacecraft for scientific research missions. Goddard pioneered several fields of spacecraft development, including modular spacecraft design, which reduced costs and made it possible to repair satellites in orbit. Goddard’s Solar Max satellite, launched in 1980, was repaired by astronauts on the Space Shuttle Challenger in 1984. The Hubble Space Telescope, launched in 1990, remains in service and continues to grow in capability thanks to its modular design and multiple servicing missions by the Space Shuttle.

    Today, the center remains involved in each of NASA’s key programs. Goddard has developed more instruments for planetary exploration than any other organization, among them scientific instruments sent to every planet in the Solar System. The center’s contribution to the Earth Science Enterprise includes several spacecraft in the Earth Observing System fleet as well as EOSDIS, a science data collection, processing, and distribution system. For the manned space flight program, Goddard develops tools for use by astronauts during extra-vehicular activity, and operates the Lunar Reconnaissance Orbiter, a spacecraft designed to study the Moon in preparation for future manned exploration.

     
  • richardmitnick 9:28 am on December 23, 2020 Permalink | Reply
    Tags: "Space weather in Proxima’s vicinity dims hopes of habitable worlds", , , , , , Exoplanets, ,   

    From University of Sydney (AU) via EarthSky: “Space weather in Proxima’s vicinity dims hopes of habitable worlds” 

    U Sidney bloc

    From University of Sydney (AU)

    via

    1

    EarthSky

    December 23, 2020
    Paul Scott Anderson

    Astronomers used radio waves to study conditions in the vicinity of Proxima Centauri, the nearest star to our sun. The results suggest Proxima’s 2 known planets are likely bathed in intense radiation from this star, casting doubt on the planets’ potential for life.

    Centauris Alpha Beta Proxima, 27 February 2012. Skatebiker.

    1
    Artist’s concept of huge flares on Proxima Centauri, which unleash ionizing radiation. This radiation could be dangerous for any possible life on planets orbiting close to the star. Image via NASA/ ESA/ G. Bacon (STScI)/ Phys.org.

    This month, even as some astronomers are talking about a possible mystery radio signal from Proxima Centauri – a signal of interest to astronomers who search for intelligent life beyond Earth – other astronomers are talking about space weather in the vicinity of this star, which is the nearest star to our sun. Space weather in Proxima’s vicinity, they are saying, might make life on its planets difficult or even impossible.

    What is space weather?

    When we hear about weather, we might think of Earth – sun, clouds, rain, wind and so on – or we might think about conditions on other planets or moons that have atmospheres. Space weather isn’t about that. It’s a sort of “weather” that originates in stars, including our own sun, and that permeates the space near a star. Space weather consists of ionizing radiation released during flares on the sun, or other stars.

    Space weather. Credit: NASA.

    The radiation can be deadly for any life forms that may exist on distant planets. That’s especially true, astronomers say, for red dwarf stars, which have more frequent flares than our sun. Red dwarf stars can be very volatile. Proxima Centauri is a red dwarf star.

    Astronomers at the University of Sydney in Australia announced the new study on December 10, 2020. These researchers used radio waves to detect and probe the space weather in Proxima’s vicinity. Our sun’s nearest neighbor at only 4.2 light-years away, Proxima is known to have at least two planets orbiting it. One, Proxima Centauri b, is almost the same mass as Earth and the other, Proxima Centauri c, is about seven times more massive. Proxima Centauri b also orbits within its stars’ habitable zone, where temperatures might allow liquid water to exist on planet’s surface. Sounds promising, right? But the new findings about flares on stars like Proxima suggests a grim prospect for life on the planets in this system.

    The researchers published their peer-reviewed findings in The Astronomical Journal on December 9.

    These astronomers worked with CSIRO’s Australian Square Kilometre Array Pathfinder (ASKAP) telescope in Western Australia and the Zadko Telescope at the University of Western Australia, as well as other instruments. Tara Murphy of the University of Sydney helped lead the study.

    Australian Square Kilometre Array Pathfinder (ASKAP) is a radio telescope array located at Murchison Radio-astronomy Observatory (MRO) in the Australian Mid West. ASKAP consists of 36 identical parabolic antennas, each 12 metres in diameter, working together as a single instrument with a total collecting area of approximately 4,000 square metres.

    3
    The Zadko telescope is used by staff at the University of Western Australia and scientists in France. Credit: ABC Radio Perth: Emma Wynne.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    University of Sydney (AU)
    Our founding principle as Australia’s first university, U Sydney was that we would be a modern and progressive institution. It’s an ideal we still hold dear today.

    When Charles William Wentworth proposed the idea of Australia’s first university in 1850, he imagined “the opportunity for the child of every class to become great and useful in the destinies of this country”.

    We’ve stayed true to that original value and purpose by promoting inclusion and diversity for the past 160 years.

    It’s the reason that, as early as 1881, we admitted women on an equal footing to male students. Oxford University didn’t follow suit until 30 years later, and Jesus College at Cambridge University did not begin admitting female students until 1974.

    It’s also why, from the very start, talented students of all backgrounds were given the chance to access further education through bursaries and scholarships.

    Today we offer hundreds of scholarships to support and encourage talented students, and a range of grants and bursaries to those who need a financial helping hand.

     
  • richardmitnick 8:36 am on September 14, 2020 Permalink | Reply
    Tags: , Exoplanets, ,   

    From Arizona State University via Science Alert: “Myriad Exoplanets in Our Galaxy Could Be Made of Diamond And Rock” 


    From Arizona State University

    via

    ScienceAlert

    Science Alert

    14 SEPTEMBER 2020
    MICHELLE STARR

    1
    (Shim/ASU/Vecteezy)

    Here in the Solar System, we have quite an interesting variety of planets, but they are limited by the composition of our Sun. Since the planets, moons, asteroids and other bodies are made out of what was left over after the Sun was finished forming, their chemistry is thought to be related to our host.

    But not all stars are made out of the same stuff as our Sun, which means that out there in the wide expanses of our galaxy, we can expect to find exoplanets wildly different from the offering in our little Solar System.

    For example, stars that are rich in carbon compared to our Sun – with more carbon than oxygen – could have exoplanets that are made primarily of diamond, with a little bit of silica, if the conditions are just right. And now, in a lab, scientists have squished and heated silicon carbide to find out what those conditions could be.

    “These exoplanets are unlike anything in our Solar System,” said geophysicist Harrison Allen-Sutter of Arizona State University’s School of Earth and Space Exploration.

    The idea that stars with a higher carbon-to-oxygen ratio than the Sun might produce diamond planets first emerged with the discovery of 55 Cancri e [The Astrophysical Journal Letters], a super-Earth exoplanet orbiting a star thought to be rich in carbon 41 light-years away.

    It was later discovered that this star wasn’t as carbon-rich as previously thought [The Astronomical Journal], which put paid to that idea – at least as far as 55 Cancri e is concerned.

    But between 12 and 17 percent of planetary systems could be located around carbon-rich stars – and with thousands of exoplanet-hosting stars identified to date, the diamond planet seems a distinct possibility.

    Scientists have already explored and confirmed the idea that such planets are likely to be composed primarily of carbides, compounds of carbon and other elements. If such a planet was rich in silicon carbide, the researchers hypothesised, and if water was present to oxidise the silicon carbide and convert it into silicon and carbon, then with sufficient heat and pressure, the carbon could become diamond.

    In order to confirm their hypothesis, they turned to a diamond anvil cell, a device used to squeeze small samples of material to very high pressures.

    They took minute samples of silicon carbide and immersed them in water. Then, the samples were placed in the diamond anvil cell, which squeezed them to pressures up to 50 gigapascals – about half a million times Earth’s atmospheric pressure at sea level. After the samples had been squeezed, the team heated them with lasers.

    In all, they conducted 18 runs of the experiment – and they found that, just as they had predicted, at high heat and high pressure, their silicon carbide samples reacted with water to convert into silica and diamond.

    Thus, the researchers concluded that at temperatures of up to 2,500 Kelvin, and pressures up to 50 gigapascals, in the presence of water, silicon carbide planets could become oxidised, and have their interior compositions dominated by silica and diamond.

    If we could identify these planets – perhaps by their density profiles, and the composition of their stars – we could therefore rule them out as planets that could host life.

    Their interiors, the researchers said, would be too hard for geological activity, and their composition would make their atmospheres inhospitable to life as we know it.

    “This is one additional step in helping us understand and characterise our ever-increasing and improving observations of exoplanets,” Allen-Sutter said.

    “The more we learn, the better we’ll be able to interpret new data from upcoming future missions like the James Webb Space Telescope and the Nancy Grace Roman Space Telescope to understand the worlds beyond on our own Solar System.”

    The research has been published in The Planetary Science Journal.

    See the full article here .


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    Please help promote STEM in your local schools.

    Stem Education Coalition


    ASU is the largest public university by enrollment in the United States. Founded in 1885 as the Territorial Normal School at Tempe, the school underwent a series of changes in name and curriculum. In 1945 it was placed under control of the Arizona Board of Regents and was renamed Arizona State College. A 1958 statewide ballot measure gave the university its present name.
    ASU is classified as a research university with very high research activity (RU/VH) by the Carnegie Classification of Institutions of Higher Education, one of 78 U.S. public universities with that designation. Since 2005 ASU has been ranked among the Top 50 research universities, public and private, in the U.S. based on research output, innovation, development, research expenditures, number of awarded patents and awarded research grant proposals. The Center for Measuring University Performance currently ranks ASU 31st among top U.S. public research universities.

    ASU awards bachelor’s, master’s and doctoral degrees in 16 colleges and schools on five locations: the original Tempe campus, the West campus in northwest Phoenix, the Polytechnic campus in eastern Mesa, the Downtown Phoenix campus and the Colleges at Lake Havasu City. ASU’s “Online campus” offers 41 undergraduate degrees, 37 graduate degrees and 14 graduate or undergraduate certificates, earning ASU a Top 10 rating for Best Online Programs. ASU also offers international academic program partnerships in Mexico, Europe and China. ASU is accredited as a single institution by The Higher Learning Commission.

     
  • richardmitnick 6:38 am on August 21, 2020 Permalink | Reply
    Tags: "The Impact of Land on an Ocean World’s Habitability", , , , , , Exoplanets,   

    From AAS NOVA: “The Impact of Land on an Ocean World’s Habitability” 

    AASNOVA

    From AAS NOVA

    19 August 2020
    Susanna Kohler

    1
    Artist’s illustration of the view from a water-covered exoplanet. [David A. Aguilar/CfA]

    Which habitable-zone planets can actually support life? A recent study uses a nearby planet — Proxima Centauri b — to examine how the presence and size of a land mass impacts the habitability of an ocean world.

    A Target for Potential Life

    In our galaxy, roughly 80% of stars are cool, dim M dwarfs — and one in six of these is thought to host an Earth-sized planet in its habitable zone. But being in a star’s habitable zone doesn’t guarantee a planet’s habitability! M-dwarf habitable-zone planets present valuable targets for observations and models to better understand which of these worlds can support life.

    Most habitable-zone planets around M dwarfs are likely tidally locked: one side of the planet experiences constant day; the other, constant night. Nominally, this would cause only one region of the planet to be heated — the point closest to the star — and the rest of the planet would be locked in darkness and ice. But if the planet is covered in a dynamic ocean, heat can be transported around the planet via ocean currents, affecting the potential habitability of the world.

    Do continents get in the way of this heat transport? And how do land masses affect the circulation of nutrients in the ocean, critical for sustaining ocean-based photosynthetic life? A new study explores the particular case of a tidally locked ocean planet with a continent — and it uses the nearby Proxima Centauri b as a model to do so.

    Centauris Alpha Beta Proxima 27, February 2012. Skatebiker

    Modeling a Nearby World

    At just 4.2 light-years away, Proxima b is the closest known exoplanet and presents an excellent target for future follow-up observations. This habitable-zone M-dwarf planet is probably tidally locked, and estimates of its density have led to speculation that the planet is covered in a large ocean.

    2
    Possible depiction of Proxima Centauri b. Credit: ESO M. Kornmesser

    3
    Ocean heat transport in the authors’ models for varying continent size; from top to bottom, continents (noted as the white rectangle in the figure) cover 0%, 4%, 22%, and 39% of the planet surface. Continents at the substellar point inhibit ocean heat transport. [Adapted from Salazar et al. 2020]

    In a recent publication led by Andrea Salazar, a team of scientists from the University of Chicago has used a general circulation model to explore how heat and nutrients are transported on an ocean-covered, tidally locked Proxima b — both with and without the presence of a land mass in the ocean.

    Salazar and collaborators placed a continent at the point on the planet closest to the star — because land masses are thought to migrate to the planet–star axis over time — and tested a range of continent sizes, covering from 0 to 40% of the total planet surface.

    Promising Outcomes

    The authors find that the presence of a continent decreases how efficiently heat and nutrients are transported from the dayside to the nightside of the planet — the larger the continent, the less efficient the transport. Nonetheless, in all cases, an ice-free ocean is maintained on the planetary dayside, and nutrients are circulated and delivered to the layer of the ocean where photosynthesis is viable, providing ideal conditions for photosynthetic marine life.

    This work suggests that the presence of both a dynamic ocean and continents won’t decrease the habitability prospects of tidally locked planets like Proxima b. This is good news as we prepare for future observations with the James Webb Space Telescope, which may provide further insight into this nearby, potentially habitable world and others like it.

    Citation

    “The Effect of Substellar Continent Size on Ocean Dynamics of Proxima Centauri b,” Andrea M. Salazar et al 2020 ApJL 896 L16.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab94c1

    See the full article here .


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    Please help promote STEM in your local schools.

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    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 8:56 am on July 4, 2020 Permalink | Reply
    Tags: , , , Exoplanets, , , TESS mission discovers massive ice giant", The exoplanet UCF-1.01, TOI-849 b is the most massive Neptune-sized planet discovered to date and the first to have a density that is comparable to Earth.   

    From MIT News: “TESS mission discovers massive ice giant” 

    MIT News

    From MIT News

    July 1, 2020
    Jennifer Chu

    1
    In our solar system, the “ice giants” Neptune and Uranus are far less dense than rocky Venus and Earth. But astrophysicists on NASA’s TESS mission have now found an exoplanet, TOI-849b, that appears to be 40 times more massive than Earth, yet just as dense. This illustration depicts the exoplanet, UCF-1.01. Like TOI-849b, this exoplanet also orbits close to a star and is like “hot Neptune.” Image credit: NASA/JPL-Caltech.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    The “ice giant” planets Neptune and Uranus are much less dense than rocky, terrestrial planets such as Venus and Earth. Beyond our solar system, many other Neptune-sized planets, orbiting distant stars, appear to be similarly low in density.

    Now, a new planet discovered by NASA’s Transiting Exoplanet Survey Satellite, TESS, seems to buck this trend. The planet, named TOI-849 b, is the 749th “TESS Object of Interest” identified to date. Scientists spotted the planet circling a star about 750 light years away every 18 hours, and estimate it is about 3.5 times larger than Earth, making it a Neptune-sized planet. Surprisingly, this far-flung Neptune appears to be 40 times more massive than Earth and just as dense.

    TOI-849 b is the most massive Neptune-sized planet discovered to date, and the first to have a density that is comparable to Earth.

    “This new planet is more than twice as massive as our own Neptune, which is really unusual,” says Chelsea Huang, a postdoc in MIT’s Kavli Institute for Astrophysics and Space Research, and a member of the TESS science team. “Imagine if you had a planet with Earth’s average density, built up to 40 times the Earth’s mass. It’s quite crazy to think what’s happening at the center of a planet with that kind of pressure.”

    The discovery is reported today in the journal Nature. The study’s authors include Huang and members of the TESS science team at MIT.

    A blasted Jupiter?

    Since its launch on April 18, 2018, the TESS satellite has been scanning the skies for planets beyond our solar system. The project is one of NASA’s Astrophysics Explorer missions and is led and operated by MIT. TESS is designed to survey almost the entire sky by pivoting its view every month to focus on a different patch of the sky as it orbits the Earth. As it scans the sky, TESS monitors the light from the brightest, nearest stars, and scientists look for periodic dips in starlight that may signal that a planet is crossing in front of a star.

    Data taken by TESS, in the form of a star’s light curve, or measurements of brightness, is first made available to the TESS science team, an international, multi-institute group of researchers led by scientists at MIT. These researchers get a first look at the data to identify promising planet candidates, or TESS Objects of Interest. These are shared publicly with the general scientific community along with the TESS data for further analysis.

    For the most part, astronomers focus their search for planets on the nearest, brightest stars that TESS has observed. Huang and her team at MIT, however, recently had some extra time to look over data during September and October of 2018, and wondered if anything could be found among the fainter stars. Sure enough, they discovered a significant number of transit-like dips from a star 750 light years away, and soon after, confirmed the existence of TOI-849 b.

    “Stars like this usually don’t get looked at carefully by our team, so this discovery was a happy coincidence,” Huang says.

    Follow-up observations of the faint star with a number of ground-based telescopes further confirmed the planet and also helped to determine its mass and density.

    Huang says that TOI-849 b’s curious proportions are challenging existing theories of planetary formation.

    “We’re really puzzled about how this planet formed,” Huang says. “All the current theories don’t fully explain why it’s so massive at its current location. We don’t expect planets to grow to 40 Earth masses and then just stop there. Instead, it should just keep growing, and end up being a gas giant, like a hot Jupiter, at several hundreds of Earth masses.”

    One hypothesis scientists have come up with to explain the new planet’s mass and density is that perhaps it was once a much larger gas giant, similar to Jupiter and Saturn — planets with more massive envelopes of gas that enshroud cores thought to be as dense as the Earth.

    As the TESS team proposes in the new study, over time, much of the planet’s gassy envelope may have been blasted away by the star’s radiation — not an unlikely scenario, as TOI-849 b orbits extremely close to its host star. Its orbital period is just 0.765 days, or just over 18 hours, which exposes the planet to about 2,000 times the solar radiation that Earth receives from the sun. According to this model, the Neptune-sized planet that TESS discovered may be the remnant core of a much more massive, Jupiter-sized giant.

    “If this scenario is true, TOI-849 b is the only remnant planet core, and the largest gas giant core known to exist,” says Huang. “This is something that gets scientists really excited, because previous theories can’t explain this planet.”

    This research was funded, in part, by NASA.

    See the full article here .


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    Please help promote STEM in your local schools.


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    MIT Seal

    The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

    MIT Campus

     
  • richardmitnick 3:58 pm on June 16, 2020 Permalink | Reply
    Tags: "As many as six billion Earth-like planets in our galaxy according to new estimates", , , , , Exoplanets, Kepler data continues to deliver.,   

    From University of British Columbia: “As many as six billion Earth-like planets in our galaxy, according to new estimates” 

    U British Columbia bloc

    From University of British Columbia

    via


    From phys.org

    June 16, 2020

    To be considered Earth-like, a planet must be rocky, roughly Earth-sized and orbiting Sun-like (G-type) stars. It also has to orbit in the habitable zones of its star—the range of distances from a star in which a rocky planet could host liquid water, and potentially life, on its surface.

    1
    Artist’s conception of Kepler telescope observing planets transiting a distant star. Credit: NASA Ames/W Stenzel.

    “My calculations place an upper limit of 0.18 Earth-like planets per G-type star,” says UBC researcher Michelle Kunimoto, co-author of the new study in The Astronomical Journal. “Estimating how common different kinds of planets are around different stars can provide important constraints on planet formation and evolution theories, and help optimize future missions dedicated to finding exoplanets.”

    According to UBC astronomer Jaymie Matthews: “Our Milky Way has as many as 400 billion stars, with seven percent of them being G-type. That means less than six billion stars may have Earth-like planets in our Galaxy.”

    Previous estimates of the frequency of Earth-like planets range from roughly 0.02 potentially habitable planets per Sun-like star, to more than one per Sun-like star.

    Typically, planets like Earth are more likely to be missed by a planet search than other types, as they are so small and orbit so far from their stars. That means that a planet catalog represents only a small subset of the planets that are actually in orbit around the stars searched. Kunimoto used a technique known as ‘forward modeling’ to overcome these challenges.

    “I started by simulating the full population of exoplanets around the stars Kepler searched,” she explained. “I marked each planet as ‘detected’ or ‘missed’ depending on how likely it was my planet search algorithm would have found them. Then, I compared the detected planets to my actual catalog of planets. If the simulation produced a close match, then the initial population was likely a good representation of the actual population of planets orbiting those stars.”

    Kunimoto’s research also shed more light on one of the most outstanding questions in exoplanet science today: the ‘radius gap’ of planets. The radius gap demonstrates that it is uncommon for planets with orbital periods less than 100 days to have a size between 1.5 and two times that of Earth. She found that the radius gap exists over a much narrower range of orbital periods than previously thought. Her observational results can provide constraints on planet evolution models that explain the radius gap’s characteristics.

    Previously, Kunimoto searched archival data from 200,000 stars of NASA’s Kepler mission. She discovered 17 new planets outside of the Solar System, or exoplanets, in addition to recovering thousands of already known planets.

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    U British Columbia Campus

    The University of British Columbiais a global centre for research and teaching, consistently ranked among the 40 best universities in the world. Since 1915, UBC’s West Coast spirit has embraced innovation and challenged the status quo. Its entrepreneurial perspective encourages students, staff and faculty to challenge convention, lead discovery and explore new ways of learning. At UBC, bold thinking is given a place to develop into ideas that can change the world.

     
  • richardmitnick 11:15 am on May 28, 2020 Permalink | Reply
    Tags: , , , , , Exoplanets, Possible disintegrating planet in the nearby planetary system DMPP-1.   

    From AAS NOVA: ” Are We Watching a Planet Disintegrate?” 

    AASNOVA

    From AAS NOVA

    27 May 2020
    Susanna Kohler

    1
    Artist’s illustration of the possible disintegrating planet in the nearby planetary system DMPP-1. [Mark A. Garlick/Haswell/ Barnes/Staab/Open University]

    Among the wealth of exoplanets we’ve discovered beyond our solar system, some are temperate, some less so. New observations have now revealed what may be a particularly inhospitable environment: a planet literally disintegrating as it orbits its host.

    2
    Artist’s illustration of another DMPP-discovered planetary system, DMPP-2. [Mark A. Garlick/Haswell/ Barnes/Staab/Open University]

    Peering Through the Shroud

    With initial observations in 2015, the Dispersed Matter Planet Project (DMPP) promised an innovative approach to hunting for exoplanets closely orbiting their hosts. Using high-cadence, high-precision radial velocity measurements, the project targets bright nearby stars that shows signatures of being shrouded in hot circumstellar gas. By looking for tiny radial-velocity wiggles in the star’s signal, the DMPP team hopes to detect small planets that are losing mass as they orbit close to their hot hosts.

    Radial Velocity Method-Las Cumbres Observatory

    In December 2019, DMPP announced its first discoveries: six planets orbiting around three different target stars. Now, in a new publication led by scientist Mark Jones (The Open University, UK), the team has revisited the first of these systems, DMPP-1, with follow-up photometry from the Transiting Exoplanet Survey Satellite (TESS).

    NASA/MIT TESS replaced Kepler in search for exoplanets

    Intriguingly, the radial-velocity-detected planets are not the only signals from this system.

    Missing the Expected, but Finding the Unexpected

    DMPP-1 is a 2-billion-year-old star located just over 200 light-years away. The radial-velocity observations of this system revealed the gravitational tugs of four planets all orbiting with periods of less than 19 days. The radial-velocity data suggest that this system is probably near edge-on and contains three super-Earths and one Neptune-like planet.

    Jones and collaborators began their photometric follow-up by searching TESS data for evidence of these four planets transiting across the host star’s face. Interestingly, they found no sign of transits at the predicted periods — indicating that the four radial-velocity planets are either smaller than expected, or that the system isn’t quite edge-on after all, so the planets don’t pass directly in front of the star.

    The authors did, however, find a new signal: a weak transit detection with a period of just ~3.3 days. This signal doesn’t match any of the known radial-velocity planets.

    A Disappearing Planet?

    What might this marginal detection be? Its variable transit depths, short period, and apparent small size are all consistent with a catastrophically disintegrating exoplanet — a close-in, small, rocky planet that is so irradiated by its host that its rocky surface is being sublimated. As time goes on, such a planet will eventually disintegrate into nothing.

    This transit signal still needs to be confirmed with additional follow-up photometric observations. Assuming it proves to be a true detection, however, such a disintegrating, rocky planet orbiting a bright nearby star would provide a veritable gold mine of information.

    By exploring the transit signals from DMPP-1 with future technology like the James Webb Space Telescope, we will be able to examine the composition of the ablated material, potentially revealing clues as to how hot, rocky inner planets form and evolve.

    Citation

    “A Possible Transit of a Disintegrating Exoplanet in the Nearby Multiplanet System DMPP-1,” Mark H. Jones et al 2020 ApJL 895 L17.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab8f2b

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

    The mission of the American Astronomical Society is to enhance and share humanity’s scientific understanding of the Universe.

    The Society, through its publications, disseminates and archives the results of astronomical research. The Society also communicates and explains our understanding of the universe to the public.
    The Society facilitates and strengthens the interactions among members through professional meetings and other means. The Society supports member divisions representing specialized research and astronomical interests.
    The Society represents the goals of its community of members to the nation and the world. The Society also works with other scientific and educational societies to promote the advancement of science.
    The Society, through its members, trains, mentors and supports the next generation of astronomers. The Society supports and promotes increased participation of historically underrepresented groups in astronomy.
    The Society assists its members to develop their skills in the fields of education and public outreach at all levels. The Society promotes broad interest in astronomy, which enhances science literacy and leads many to careers in science and engineering.

    Adopted June 7, 2009

     
  • richardmitnick 1:28 pm on May 15, 2020 Permalink | Reply
    Tags: , , , Carole Haswell, , , , Exoplanets   

    From ESOblog: “Hunting hot exoplanets” 

    ESO 50 Large

    From ESOblog

    15 May 2020
    Science Snapshots

    1
    Carole Haswell

    In December 2019, astronomers announced that they had efficiently discovered and characterised planets outside the Solar System using an innovative technique. So far, the researchers have used the technique with ESO’s HARPS instrument to find six exoplanets, some of which hold the key to unlocking the geology of rocky planets. We spoke to lead researcher Carole Haswell from the Open University in the UK to find out more about the project and the implications of these discoveries.

    ESO 3.6m telescope & HARPS at Cerro LaSilla, Chile, 600 km north of Santiago de Chile at an altitude of 2400 metres.

    2
    Artist’s impression of the mass-losing giant planet DMPP-2b, which orbits the pulsating star DMPP-2 every five days. The star is viewed through a cloud of gas lost from the hot planet.
    Credit: Mark A. Garlick / markgarlick.com. Science credit: Haswell / Barnes / Staab

    Q. The Dispersed Matter Planet Project (DMPP) aims to find lots of new exoplanets. What motivated you to start this project?

    A. The project actually grew out of some research we did a decade ago using the Hubble Space Telescope. We were looking at giant exoplanets, and found that the chromosphere of one of the host stars was missing. It seemed extremely unlikely that this star would be structured differently to every other star we know of, so we had another idea: when planets orbit close to their host star, they are heated very vigorously which makes them lose mass. We figured that some of this mass could form a gas shroud that envelops the entire planetary system and absorbs the light from the star’s chromosphere, preventing us from seeing it.

    So, we had the idea that if we see a star with missing chromospheric emission, we know that there is a hot mass-losing planet present, and could actually deduce a lot of information about such a planet. In this way, we came up with a new and efficient technique to discover new low-mass planets orbiting close to their parent star.

    What makes the project really special is our target star selection. Astronomers are beginning to suspect that most stars have planets orbiting them, but when we know what kind of planet a star might host, we can tailor the observations to find out about the planet much more quickly. And this is exactly what we’ve been doing here.

    Q. Could you tell us a bit about how this new planet-searching technique works?

    A. We searched through existing data on 6000 stars to find any that were structured like the Sun but with missing emission from their chromospheres. Of these 6000, we found about 40 that we thought could host very hot mass-losing planets. As these were all nearby stars, we guessed that these planets would have been found already if they were large and massive, so we thought they must be small, light planets. Therefore we designed observations to find them using the very sensitive HARPS instrument on the ESO 3.6-metre telescope [below and above].

    Because we were expecting low-mass planets orbiting close to their host stars — and therefore orbiting very quickly — we needed to get frequent measurements of the same star to see the differences during the planet’s orbit. So we looked at each star several times a night, which is much more often than observations are usually designed.

    Visiting La Silla Observatory to use the ESO 3.6-metre telescope was one of the most amazing experiences of my life. I’d used the New Technology Telescope [below] some years ago, but because I believe that this research is the best idea I’ve had in my whole career, it was especially exciting to go this time round.

    Q. What makes HARPS so good at finding new planetary systems?

    A. For this project, we are using the radial velocity method to detect planets, which means we measure how quickly the star moves towards and away from us. When a planet orbits a star, it pulls the star towards itself slightly. This means that when the planet orbits the star, the star is also executing a much smaller orbit in response. The star moves towards us while the planet moves away from us and vice versa. We can detect these changes in the star’s velocity from Earth.


    The radial velocity method for finding exoplanets. Credit: ESO/L. Calçada.

    We chose to use HARPS because it is by far the best general user radial velocity instrument that we were allowed to propose for — it can measure the velocity of a star with a precision of less than one metre per second! It’s fantastic to be in an ESO Member State with the opportunity to use such an instrument.

    Q. So why do you think it is important for us to search for new exoplanets?

    A. One of the biggest human questions is about our place in the Universe; how special the Solar System is and how special Earth is. And one of the big pushes in exoplanet science is to extend discovery methods to be able to see planets like Earth orbiting their host stars at the same distance that Earth orbits the Sun. The idea is that these Earth-like planets could be good candidates for hosting life.

    But it’s also important to find a whole range of planetary systems to see how planets form and evolve and to determine how typical the Solar System is. The planets we are studying through this project aren’t similar to our neighbours in the Solar System, but it is nonetheless important to study them because it gives us the opportunity to better understand a different type of planet, which is important to generally understand the geology and geochemistry of planetary systems.

    With further study of the systems we’ve found to host exoplanets, we could work out the chemical composition of the gas shroud, which would reveal what type of rock the surfaces of these planets are made of. This will help us pin down how planets are built, and whether the Earth is normal.

    Q. How has the DMPP been going so far? Have you had any surprising discoveries?

    A. We started making observations in 2015, and we’ve already discovered six exoplanets using relatively little telescope time compared to more traditional methods. One of the most interesting stars we looked at so far actually turned out to be two stars! The tiny second star in the binary system is right at the lower limit of hydrogen burning, meaning it is just massive enough to be a proper star like the Sun. If it had slightly less material, it would be a brown dwarf. This star is faint and had therefore never been detected before. Finding this extremely low mass star was interesting in its own right, but we also found a planet in this system that is 2–3 times the mass of Earth and orbits the larger star in just seven days, which is unusually quick. The planet doesn’t fit with our theories of planet formation because the smaller star’s presence means there wouldn’t have been enough rocky material to form the planet where we see it. The second star must have affected the planet’s orbit, somehow pushing it closer to the larger star.

    We would really like to study this system in more detail; if we can get more radial velocity data, we could see if there are any other planets, pin down the properties of the planet we’ve already discovered, and look at the atmosphere of the smaller star to see how it changes as it gets close to the larger star.

    Q. Are there any challenges that you’ve had to overcome?

    A. For many of our target stars we have detected more than one orbiting planet, so it took us a while to disentangle the signals from each other to figure out the exact number of planets and their orbital periods. This meant it was longer than expected before we could publish our results, so the committee that allocates telescope time started becoming sceptical and we had to persuade them that our research really is worthwhile. We’ve now published several papers on our discoveries, and we were allocated more time to continue the project — both to look at more systems and to investigate the most interesting ones in more detail. Unfortunately these observations couldn’t take place because of the closure of the observatory due to COVID-19, but we are really keen to continue as soon as it is safe to do so!

    See the full article here .


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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

    ESO VLT at Cerro Paranal in the Atacama Desert, •ANTU (UT1; The Sun ),
    •KUEYEN (UT2; The Moon ),
    •MELIPAL (UT3; The Southern Cross ), and
    •YEPUN (UT4; Venus – as evening star).
    elevation 2,635 m (8,645 ft) from above Credit J.L. Dauvergne & G. Hüdepohl atacama photo,

    Glistening against the awesome backdrop of the night sky above ESO_s Paranal Observatory, four laser beams project out into the darkness from Unit Telescope 4 UT4 of the VLT, a major asset of the Adaptive Optics system


    ESO LaSilla
    ESO/Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT 4 lasers on Yepun


    ESO Vista Telescope
    ESO/Vista Telescope at Cerro Paranal, with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO NTT
    ESO/NTT at Cerro LaSilla 600 km north of Santiago de Chile at an altitude of 2400 metres.

    ESO VLT Survey telescope
    VLT Survey Telescope at Cerro Paranal with an elevation of 2,635 metres (8,645 ft) above sea level.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile. located at the summit of the mountain at an altitude of 3,060 metres (10,040 ft).


    ESO APEXESO/MPIfR APEX high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft)at the Llano de Chajnantor Observatory in the Atacama desert.

    A novel gamma ray telescope under construction on Mount Hopkins, Arizona. a large project known as the Cherenkov Telescope Array, composed of hundreds of similar telescopes to be situated in the Canary Islands and Chile. The telescope on Mount Hopkins will be fitted with a prototype high-speed camera, assembled at the University of Wisconsin–Madison, and capable of taking pictures at a billion frames per second. Credit: Vladimir Vassiliev

     
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