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  • richardmitnick 1:23 pm on June 21, 2017 Permalink | Reply
    Tags: , , , , , Mini-Neptunes, NASA Has Discovered Hundreds of Potential New Planets - And 10 May Be Like Earth, , , Super-earths, The new Earths next door?, You'd need 400 Keplers to cover the whole sky   

    From Science Alert: “NASA Has Discovered Hundreds of Potential New Planets – And 10 May Be Like Earth” 


    Science Alert

    20 JUN 2017

    An illustration of Earth-like planets Image: NASA/JPL-Caltech/R. Hurt

    Astronomers are ecstatic.

    NASA scientists on Monday announced the discovery of 219 new objects beyond our solar system that are almost certainly planets. What’s more, 10 of these worlds may be rocky, about the size of Earth, and habitable.

    The data comes from the space agency’s long-running Kepler exoplanet-hunting mission. From March 2009 through May 2013, Kepler stared down about 145,000 sun-like stars in a tiny section of the night sky near the constellation Cygnus.

    Most of the stars in Kepler’s view were hundreds or thousands of light-years away, so there’s little chance humans will ever visit them – or at least any time soon. However, the data could tell astronomers how common Earth-like planets are, and what the chances of finding intelligent extraterrestrial life might be.

    “We have taken our telescope and we have counted up how many planets are similar to the Earth in this part of the sky,” Susan Thompson, a Kepler research scientist at the SETI Institute, said during a press conference at NASA Ames Research Center on Monday.

    SETI Institute

    “We said, ‘how many planets there are similar to Earth?’ With the data I have, I can now make that count,” she said.

    “We’re going to determine how common other planets are. Are there other places we could live in the galaxy that we don’t yet call home?”

    Added to Kepler’s previous discoveries, the 10 new Earth-like planet candidates make 49 total, Thompson said. If any of them have stable atmospheres, there’s even a chance they could harbour alien life.

    The new Earths next door?


    Scientists wouldn’t say too much about the 10 new planets, only that they appear to be roughly Earth-sized and orbit in their stars’ ‘habitable zone’ – where water is likely to be stable and liquid, not frozen or boiled away.

    That doesn’t guarantee these planets are actually habitable, though. Beyond harboring a stable atmosphere, things like plate tectonics and not being tidally locked may also be essential.

    However, Kepler researchers suspect that almost countless Earth-like planets are waiting to be found. This is because the telescope can only ‘see’ exoplanets that transit, or pass, in front of their stars.

    Planet transit. NASA/Ames

    The transit method of detecting planets that Kepler scientists use involves looking for dips in a star’s brightness, which are caused by a planet blocking out a fraction of the starlight (similar to how the Moon eclipses the Sun).

    Because most planets orbit in the same disk or plane, and that plane is rarely aligned with Earth, that means Kepler can only see a fraction of distant solar systems. (Exoplanets that are angled slightly up or down are invisible to the transit method.)

    Despite those challenges, Kepler has revealed the existence of 4,034 planet candidates, with 2,335 of those confirmed as exoplanets. And these are just the worlds in 0.25 percent of the night sky.

    “In fact, you’d need 400 Keplers to cover the whole sky,” Mario Perez, a Kepler program scientist at NASA, said during the briefing.

    The biggest number of planets appear to be a completely new class of planets, called “mini-Neptunes”, Benjamin Fulton, an astronomer at the University of Hawaii at Manoa and California Institute of Technology, said during the briefing.

    Such worlds are between the size of Earth and the gas giants of our solar system, and are likely the most numerous kind in the universe. ‘Super-Earths’, which are rocky planets that can be up to 10 times more massive than our own, are also very common.

    A popular new image I have used before. NASA/Kepler/Caltech (T. Pyle)

    “This number could have been very, very small,” Courtney Dressing, an astronomer at Caltech, said during the briefing. “I, for one, am ecstatic.”

    Kepler’s big back-up plan

    NASA Ames/W. Stenzel and JPL-Caltech/R. Hurt

    Gravitational microlensing, S. Liebes, Physical Review B, 133 (1964): 835

    Kepler finished collecting its first mission’s data in May 2013. It has taken scientists years to analyse that information because it’s often difficult parse, interpret, and verify.

    Thompson said this new Kepler data analysis will be the last for this leg of the telescope’s first observations. Kepler suffered two hardware failures (and then some) that limited its ability to aim at one area of the night sky, ending its mission to look at stars that are similar to the Sun.

    But scientists’ back-up plan, called the K2 mission, kicked off in May 2014. It takes advantage of Kepler’s restricted aim and uses it to study a variety of objects in space, including supernovas, baby stars, comets, and even asteroids.

    Although K2 is just getting off the ground, other telescopes have had success in these types of endeavours. In February, for example, a different one revealed the existence of seven rocky, Earth-size planets circling a red dwarf star.

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile interior

    ESO Belgian robotic Trappist National Telescope at Cerro La Silla, Chile

    The TRAPPIST-1 star, an ultracool dwarf, is orbited by seven Earth-size planets (NASA).

    Such dwarf stars are the most common in the universe and can have more angry outbursts of solar flares and coronal mass ejections than sun-like stars.

    But paradoxically, they seem to harbour the most small, rocky planets in a habitable zone in the universe – and thus may be excellent places to look for signs of alien life.

    See the full article here .

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  • richardmitnick 11:50 am on May 5, 2015 Permalink | Reply
    Tags: , , Super-earths,   

    From Spitzer via Cambridge: “Astronomers find first evidence of changing conditions on a super Earth” 

    U Cambridge bloc

    Cambridge University

    05 May 2015
    Sarah Collins


    Astronomers have detected wildly changing temperatures on a super Earth – the first time any atmospheric variability has been observed on a rocky planet outside the solar system – and believe it could be due to huge amounts of volcanic activity, further adding to the mystery of what had been nicknamed the ‘diamond planet’.

    For the first time, researchers led by the University of Cambridge have detected atmospheric variability on a rocky planet outside the solar system, and observed a nearly threefold change in temperature over a two year period. Although the researchers are quick to point out that the cause of the variability is still under investigation, they believe the readings could be due to massive amounts of volcanic activity on the surface. The ability to peek into the atmospheres of rocky ‘super Earths’ and observe conditions on their surfaces marks an important milestone towards identifying habitable planets outside the solar system.

    Using NASA’s Spitzer Space Telescope, the researchers observed thermal emissions coming from the planet, called 55 Cancri e – orbiting a sun-like star located 40 light years away in the Cancer constellation – and for the first time found rapidly changing conditions, with temperatures on the hot ‘day’ side of the planet swinging between 1000 and 2700 degrees Celsius.

    NASA Spitzer Telescope

    “This is the first time we’ve seen such drastic changes in light emitted from an exoplanet, which is particularly remarkable for a super Earth,” said Dr Nikku Madhusudhan of Cambridge’s Institute of Astronomy, a co-author on the new study. “No signature of thermal emissions or surface activity has ever been detected for any other super Earth to date.”

    Although the interpretations of the new data are still preliminary, the researchers believe the variability in temperature could be due to huge plumes of gas and dust which occasionally blanket the surface, which may be partially molten. The plumes could be caused by exceptionally high rates of volcanic activity, higher than what has been observed on Io, one of Jupiter’s moons and the most geologically active body in the solar system.

    “We saw a 300 percent change in the signal coming from this planet, which is the first time we’ve seen such a huge level of variability in an exoplanet,” said Dr Brice-Olivier Demory of the University’s Cavendish Laboratory, lead author of the new study. “While we can’t be entirely sure, we think a likely explanation for this variability is large-scale surface activity, possibly volcanism, on the surface is spewing out massive volumes of gas and dust, which sometimes blanket the thermal emission from the planet so it is not seen from Earth.”

    55 Cancri e is a ‘super Earth’: a rocky exoplanet about twice the size and eight times the mass of Earth. It is one of five planets orbiting a sun-like star in the Cancer constellation, and resides so close to its parent star that a year lasts just 18 hours. The planet is also tidally locked, meaning that it doesn’t rotate like the Earth does – instead there is a permanent ‘day’ side and a ‘night’ side. Since it is the nearest super Earth whose atmosphere can be studied, 55 Cancri e is among the best candidates for detailed observations of surface and atmospheric conditions on rocky exoplanets.

    Most of the early research on exoplanets has been on gas giants similar to Jupiter and Saturn, since their enormous size makes them easier to find. In recent years, astronomers have been able to map the conditions on many of these gas giants, but it is much more difficult to do so for super Earths: exoplanets with masses between one and ten times the mass of Earth.

    Earlier observations of 55 Cancri e pointed to an abundance of carbon, suggesting that the planet was composed of diamond. However, these new results have muddied those earlier observations considerably and opened up new questions.

    “When we first identified this planet, the measurements supported a carbon-rich model,” said Madhusudhan, who along with Demory is a member of the Cambridge Exoplanet Research Centre. “But now we’re finding that those measurements are changing in time. The planet could still be carbon rich, but now we’re not so sure – earlier studies of this planet have even suggested that it could be a water world. The present variability is something we’ve never seen anywhere else, so there’s no robust conventional explanation. But that’s the fun in science – clues can come from unexpected quarters. The present observations open a new chapter in our ability to study the conditions on rocky exoplanets using current and upcoming large telescopes.”

    The results have been published online today.

    The study was also co-authored by Professor Didier Queloz of the Cavendish Laboratory and Dr Michaël Gillon of the Université of Liège.

    See the full article here.

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    U Cambridge Campus

    The University of Cambridge[note 1] (abbreviated as Cantab in post-nominal letters[note 2]) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university.[6] It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk.[7] The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

    Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools.[8] The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States.[9] Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

  • richardmitnick 5:17 am on March 24, 2015 Permalink | Reply
    Tags: , , Super-earths   

    From Caltech: “New Research Suggests Solar System May Have Once Harbored Super-Earths” 

    Caltech Logo

    Kimm Fesenmaier

    Caltech and UC Santa Cruz Researchers Say Earth Belongs to a Second Generation of Planets

    This snapshot from a new simulation depicts a time early in the solar system’s history when Jupiter likely made a grand inward migration (here, Jupiter’s orbit is the thick white circle). As it moved inward, Jupiter picked up primitive planetary building blocks, or planetesimals, and drove them into eccentric orbits (turquoise) that overlapped the unperturbed part of the planetary disk (yellow), setting off a cascade of collisions that would have ushered any interior planets into the sun.
    Credit: K.Batygin/Caltech

    Long before Mercury, Venus, Earth, and Mars formed, it seems that the inner solar system may have harbored a number of super-Earths—planets larger than Earth but smaller than Neptune. If so, those planets are long gone—broken up and fallen into the sun billions of years ago largely due to a great inward-and-then-outward journey that Jupiter made early in the solar system’s history.

    This possible scenario has been suggested by Konstantin Batygin, a Caltech planetary scientist, and Gregory Laughlin of UC Santa Cruz in a paper that appears the week of March 23 in the online edition of the Proceedings of the National Academy of Sciences (PNAS). The results of their calculations and simulations suggest the possibility of a new picture of the early solar system that would help to answer a number of outstanding questions about the current makeup of the solar system and of Earth itself. For example, the new work addresses why the terrestrial planets in our solar system have such relatively low masses compared to the planets orbiting other sun-like stars.

    “Our work suggests that Jupiter’s inward-outward migration could have destroyed a first generation of planets and set the stage for the formation of the mass-depleted terrestrial planets that our solar system has today,” says Batygin, an assistant professor of planetary science. “All of this fits beautifully with other recent developments in understanding how the solar system evolved, while filling in some gaps.”

    Thanks to recent surveys of exoplanets—planets in solar systems other than our own—we know that about half of sun-like stars in our galactic neighborhood have orbiting planets. Yet those systems look nothing like our own. In our solar system, very little lies within Mercury’s orbit; there is only a little debris—probably near-Earth asteroids that moved further inward—but certainly no planets. That is in sharp contrast with what astronomers see in most planetary systems. These systems typically have one or more planets that are substantially more massive than Earth orbiting closer to their suns than Mercury does, but very few objects at distances beyond.

    “Indeed, it appears that the solar system today is not the common representative of the galactic planetary census. Instead we are something of an outlier,” says Batygin. “But there is no reason to think that the dominant mode of planet formation throughout the galaxy should not have occurred here. It is more likely that subsequent changes have altered its original makeup.”

    According to Batygin and Laughlin, Jupiter is critical to understanding how the solar system came to be the way it is today. Their model incorporates something known as the Grand Tack scenario, which was first posed in 2001 by a group at Queen Mary University of London and subsequently revisited in 2011 by a team at the Nice Observatory. That scenario says that during the first few million years of the solar system’s lifetime, when planetary bodies were still embedded in a disk of gas and dust around a relatively young sun, Jupiter became so massive and gravitationally influential that it was able to clear a gap in the disk. And as the sun pulled the disk’s gas in toward itself, Jupiter also began drifting inward, as though carried on a giant conveyor belt.

    “Jupiter would have continued on that belt, eventually being dumped onto the sun if not for Saturn,” explains Batygin. Saturn formed after Jupiter but got pulled toward the sun at a faster rate, allowing it to catch up. Once the two massive planets got close enough, they locked into a special kind of relationship called an orbital resonance, where their orbital periods were rational—that is, expressible as a ratio of whole numbers. In a 2:1 orbital resonance, for example, Saturn would complete two orbits around the sun in the same amount of time that it took Jupiter to make a single orbit. In such a relationship, the two bodies would begin to exert a gravitational influence on one another.

    “That resonance allowed the two planets to open up a mutual gap in the disk, and they started playing this game where they traded angular momentum and energy with one another, almost to a beat,” says Batygin. Eventually, that back and forth would have caused all of the gas between the two worlds to be pushed out, a situation that would have reversed the planets’ migration direction and sent them back outward in the solar system. (Hence, the “tack” part of the Grand Tack scenario: the planets migrate inward and then change course dramatically, something like a boat tacking around a buoy.)

    In an earlier model developed by Bradley Hansen at UCLA, the terrestrial planets conveniently end up in their current orbits with their current masses under a particular set of circumstances—one in which all of the inner solar system’s planetary building blocks, or planetesimals, happen to populate a narrow ring stretching from 0.7 to 1 astronomical unit (1 astronomical unit is the average distance from the sun to Earth), 10 million years after the sun’s formation. According to the Grand Tack scenario, the outer edge of that ring would have been delineated by Jupiter as it moved toward the sun on its conveyor belt and cleared a gap in the disk all the way to Earth’s current orbit.

    But what about the inner edge? Why should the planetesimals be limited to the ring on the inside? “That point had not been addressed,” says Batygin.

    He says the answer could lie in primordial super-Earths. The empty hole of the inner solar system corresponds almost exactly to the orbital neighborhood where super-Earths are typically found around other stars. It is therefore reasonable to speculate that this region was cleared out in the primordial solar system by a group of first-generation planets that did not survive.

    Batygin and Laughlin’s calculations and simulations show that as Jupiter moved inward, it pulled all the planetesimals it encountered along the way into orbital resonances and carried them toward the sun. But as those planetesimals got closer to the sun, their orbits also became elliptical. “You cannot reduce the size of your orbit without paying a price, and that turns out to be increased ellipticity,” explains Batygin. Those new, more elongated orbits caused the planetesimals, mostly on the order of 100 kilometers in radius, to sweep through previously unpenetrated regions of the disk, setting off a cascade of collisions among the debris. In fact, Batygin’s calculations show that during this period, every planetesimal would have collided with another object at least once every 200 years, violently breaking them apart and sending them decaying into the sun at an increased rate.

    The researchers did one final simulation to see what would happen to a population of super-Earths in the inner solar system if they were around when this cascade of collisions started. They ran the simulation on a well-known extrasolar system known as Kepler-11, which features six super-Earths with a combined mass 40 times that of Earth, orbiting a sun-like star. The result? The model predicts that the super-Earths would be shepherded into the sun by a decaying avalanche of planetesimals over a period of 20,000 years.

    “It’s a very effective physical process,” says Batygin. “You only need a few Earth masses worth of material to drive tens of Earth masses worth of planets into the sun.”

    Batygin notes that when Jupiter tacked around, some fraction of the planetesimals it was carrying with it would have calmed back down into circular orbits. Only about 10 percent of the material Jupiter swept up would need to be left behind to account for the mass that now makes up Mercury, Venus, Earth, and Mars.

    From that point, it would take millions of years for those planetesimals to clump together and eventually form the terrestrial planets—a scenario that fits nicely with measurements that suggest that Earth formed 100–200 million years after the birth of the sun. Since the primordial disk of hydrogen and helium gas would have been long gone by that time, this could also explain why Earth lacks a hydrogen atmosphere. “We formed from this volatile-depleted debris,” says Batygin.

    And that sets us apart in another way from the majority of exoplanets. Batygin expects that most exoplanets—which are mostly super-Earths—have substantial hydrogen atmospheres, because they formed at a point in the evolution of their planetary disk when the gas would have still been abundant. “Ultimately, what this means is that planets truly like Earth are intrinsically not very common,” he says.

    The paper also suggests that the formation of gas giant planets such as Jupiter and Saturn—a process that planetary scientists believe is relatively rare—plays a major role in determining whether a planetary system winds up looking something like our own or like the more typical systems with close-in super-Earths. As planet hunters identify additional systems that harbor gas giants, Batygin and Laughlin will have more data against which they can check their hypothesis—to see just how often other migrating giant planets set off collisional cascades in their planetary systems, sending primordial super-Earths into their host stars.

    The researchers describe their work in a paper titled Jupiter’s Decisive Role in the Inner Solar System’s Early Evolution.

    See the full article here.

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
    Caltech buildings

  • richardmitnick 5:13 pm on January 6, 2015 Permalink | Reply
    Tags: , , , , , Super-earths   

    From CfA: “Super-Earths Have Long-Lasting Oceans” 

    Smithsonian Astrophysical Observatory
    Smithsonian Astrophysical Observatory

    January 5, 2015
    David A. Aguilar
    Director of Public Affairs
    Harvard-Smithsonian Center for Astrophysics

    Christine Pulliam
    Public Affairs Specialist
    Harvard-Smithsonian Center for Astrophysics

    For life as we know it to develop on other planets, those planets would need liquid water, or oceans. Geologic evidence suggests that Earth’s oceans have existed for nearly the entire history of our world. But would that be true of other planets, particularly super-Earths? New research suggests the answer is yes and that oceans on super-Earths, once established, can last for billions of years.

    “When people consider whether a planet is in the habitable zone, they think about its distance from the star and its temperature. However, they should also think about oceans, and look at super-Earths to find a good sailing or surfing destination,” says lead author Laura Schaefer of the Harvard-Smithsonian Center for Astrophysics (CfA).

    Two renderings of possible super-Earths, with Earth itself to the right for comparison

    Schaefer presented her findings today in a press conference at a meeting of the American Astronomical Society.

    Even though water covers 70 percent of Earth’s surface, it makes up a very small fraction of the planet’s overall bulk. Earth is mostly rock and iron; only about a tenth of a percent is water.

    “Earth’s oceans are a very thin film, like fog on a bathroom mirror,” explains study co-author Dimitar Sasselov (CfA).

    However, Earth’s water isn’t just on the surface. Studies have shown that Earth’s mantle holds several oceans’ worth of water that was dragged underground by plate tectonics and subduction of the ocean seafloor. Earth’s oceans would disappear due to this process, if it weren’t for water returning to the surface via volcanism (mainly at mid-ocean ridges). Earth maintains its oceans through this planet-wide recycling.

    Schaefer used computer simulations to see if this recycling process would take place on super-Earths, which are planets up to five times the mass, or 1.5 times the size, of Earth. She also examined the question of how long it would take oceans to form after the planet cooled enough for its crust to solidify.

    She found that planets two to four times the mass of Earth are even better at establishing and maintaining oceans than our Earth. The oceans of super-Earths would persist for at least 10 billion years (unless boiled away by an evolving red giant star).

    Interestingly, the largest planet that was studied, five times the mass of Earth, took a while to get going. Its oceans didn’t develop for about a billion years, due to a thicker crust and lithosphere that delayed the start of volcanic outgassing.

    Earth cutaway from core to crust, the lithosphere comprising the crust and lithospheric mantle (detail not to scale)

    “This suggests that if you want to look for life, you should look at older super-Earths,” Schaefer says.

    Sasselov agrees. “It takes time to develop the chemical processes for life on a global scale, and time for life to change a planet’s atmosphere. So, it takes time for life to become detectable.”

    This also suggests that, assuming evolution takes place at a similar rate to Earth’s, you want to search for complex life on planets that are about five and a half billion years old, a billion years older than Earth.

    See the full article here.

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    About CfA

    The Center for Astrophysics combines the resources and research facilities of the Harvard College Observatory and the Smithsonian Astrophysical Observatory under a single director to pursue studies of those basic physical processes that determine the nature and evolution of the universe. The Smithsonian Astrophysical Observatory (SAO) is a bureau of the Smithsonian Institution, founded in 1890. The Harvard College Observatory (HCO), founded in 1839, is a research institution of the Faculty of Arts and Sciences, Harvard University, and provides facilities and substantial other support for teaching activities of the Department of Astronomy. The long relationship between the two organizations, which began when the SAO moved its headquarters to Cambridge in 1955, was formalized by the establishment of a joint center in 1973. The CfA’s history of accomplishments in astronomy and astrophysics is reflected in a wide range of awards and prizes received by individual CfA scientists.

    Today, some 300 Smithsonian and Harvard scientists cooperate in broad programs of astrophysical research supported by Federal appropriations and University funds as well as contracts and grants from government agencies. These scientific investigations, touching on almost all major topics in astronomy, are organized into the following divisions, scientific departments and service groups.

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