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  • richardmitnick 9:21 am on June 25, 2022 Permalink | Reply
    Tags: "This newfound fast radio burst challenges what astronomers know about the powerful astronomical phenomena", , , , , , space.com, The new FRB is named FRB190520.   

    From SPACE.com : “This newfound fast radio burst challenges what astronomers know about the powerful astronomical phenomena” 

    From SPACE.com

    6.24.22
    Kshitij Aggarwal

    What can astronomers learn from this fast radio burst?

    1
    Researchers used a radio telescope in New Mexico to study a particularly interesting fast radio burst. (Image credit: Diana Robinson/Flickr, CC BY-NC-ND)

    “A newly discovered fast radio burst has some unique properties that are simultaneously giving astronomers important clues into what may cause these mysterious astronomical phenomena while also calling into question one of the few things scientists thought they knew about these powerful flares, as my colleagues and I describe in a new study in Nature on June 8, 2022.

    Fast radio bursts, or FRBs, are extremely bright pulses of radio waves that come from faraway galaxies. They release as much energy in a millisecond as the sun does over many days (opens in new tab). Researchers here at West Virginia University detected the first FRB back in 2007 [Science]. In the past 15 years, astronomers have detected around 800 FRBs, with more being discovered every day [The Astronomy and Astrophysics Review].

    When a telescope captures an FRB, one of the most important features researchers look at is something called dispersion. Dispersion is basically a measure of how stretched out an FRB is when it reaches Earth.

    The plasma that lies between stars and galaxies causes all light — including radio waves — to slow down, but lower frequencies feel this effect more strongly and slow down more than higher frequencies. FRBs contain a range of frequencies, so the higher frequency light in the burst hits Earth before the lower frequencies, causing the dispersion. This allows researchers to use dispersion to estimate how far from Earth an FRB originated (opens in new tab). The more stretched out an FRB is, the more plasma the signal must have passed through, the farther away the source must be.

    Why it matters

    The new FRB my colleagues and I discovered is named FRB190520 [Nature]. We found it using the Five-hundred-meter Aperture Spherical Telescope in China.

    An immediately apparent interesting thing about FRB190520 was that it is one of the only 24 repeating FRBs and repeats much more frequently than others — producing 75 bursts over a span of six months in 2020.

    Our team then used the Very Large Array, a radio telescope in New Mexico, to further study this FRB and successfully pinpointed the location of its source — a dwarf galaxy roughly 3 billion light years from Earth.

    It was then that we started to realize how truly unique and important this FRB is.

    First, we found that there is a persistent, though much fainter, radio signal being emitted [Nature] by something from the same place that FRB190520 came from. Of the more than 800 FRBs discovered to date (opens in new tab), only one other has a similar persistent radio signal.

    Second, since we were able to pinpoint that the FRB came from a dwarf galaxy, we were able to determine exactly how far away that galaxy is from Earth. But this result didn’t make sense. Much to our surprise, the distance estimate we made using the dispersion of the FRB was 30 billion light years from Earth, a distance 10 times larger than the actual 3 billion light years to the galaxy [Nature] .

    Astronomers have only been able to pinpoint the exact location — and therefore distance from Earth — of 19 other FRB sources. For the rest of the roughly 800 known FRBs, astronomers have to rely on dispersion alone to estimate their distance from Earth. For the other 19 FRBs with known locations, the distances estimated from dispersion are very similar to the real distances to their source galaxies. But this new FRB shows that estimates using dispersion can sometimes be incorrect and throws many assumptions out the window.

    1
    The top of this diagram show six spikes in radio wave brightness that are six bursts from FRB190520. The bottom half shows the frequency range for each individual burst. (Image credit: Niu, CH., Aggarwal, K., Li, D. et al., CC BY)

    What still isn’t known

    Astronomers in this new field [The Astronomy and Astrophysics Review] still don’t know what exactly produces FRBs, so every new discovery or piece of information is important.

    Our new discovery raises specific questions, including whether persistent radio signals are common, what conditions produce them and whether the same phenomenon that produces FRBs is responsible for emitting the persistent radio signal.

    And a huge mystery is why the dispersion of FRB190520 was so much greater than it should be. Was it due to something near the FRB? Was it related to the persistent radio source? Does it have to do with the matter in the galaxy where this FRB comes from? All of these questions are unanswered.

    What’s next

    My colleagues are going to focus in on studying FRB190520 using a host of different telescopes around the world. By studying the FRB, its galaxy and the space environment surrounding its source, we are hoping to find answers to many of the mysteries it revealed.

    More answers will come from other FRB discoveries in the coming years, too. The more FRBs astronomers catalog, the greater the chances of discovering FRBs with interesting properties that can help complete the puzzle of these fascinating astronomical phenomena.”

    See the full article here .

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  • richardmitnick 8:50 am on June 25, 2022 Permalink | Reply
    Tags: "Gaia spacecraft reveals mysterious 'hot Jupiter' planets can form quickly or slowly", , , , , , , space.com   

    From SPACE.com : “Gaia spacecraft reveals mysterious ‘hot Jupiter’ planets can form quickly or slowly” 

    From SPACE.com

    6.24.22
    Andrew Jones

    These massive worlds are vastly different from anything in our solar system.

    1
    An artist’s depiction of a hot Jupiter planet orbiting its star. (Image credit: NASA/Ames/JPL-Caltech)

    The existence of “hot Jupiters” is one of the oldest mysteries of the exoplanet-hunting era, but a European spacecraft is revealing some clues about how these enigmatic worlds form.

    So-called hot Jupiters are planets that are roughly as massive as Jupiter and orbit very close to their stars, usually less than one-tenth the distance at which Earth orbits the sun. Hot Jupiters are very different from anything seen in the solar system, posing questions about their formation.

    Now, new data from the European Space Agency’s Gaia spacecraft, which is tracking more than a billion stars in the Milky Way, have provided fresh insight into the formation, evolution and relative age of hot Jupiters.

    Researchers used Gaia’s measurements of objects’ positions and velocities to determine the relative age of stars. Combining this information with data on the alignment of hot Jupiters to their stars’ rotation revealed that there are multiple ways in which hot Jupiters form — both fast and slow.

    “Without this really precise method of measuring ages, there was always missing information,” Jacob Hamer, a doctoral student in the Johns Hopkins University Department of Physics and Astronomy and lead author of a new paper describing the findings, said in a statement.

    Hot Jupiters with orbits misaligned from the equators of their stars are thought to form late relative to those that are aligned, like the planets in our solar system.

    “One [formation process] occurs quickly and produces aligned systems, and [the other] occurs over longer timescales and produces misaligned systems,” Hamer said in the statement.

    The work has been accepted for publication in The Astronomical Journal.

    See the full article here .

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  • richardmitnick 4:25 pm on June 16, 2022 Permalink | Reply
    Tags: "How baby stars blow bubbles as they are ejected from their nurseries", , , , , space.com   

    From SPACE.com : “How baby stars blow bubbles as they are ejected from their nurseries” 

    From SPACE.com

    6.15.22
    Andrew Jones

    1
    A simulated star cluster partially embedded in a cloud of hydrogen gas. (Image credit: Michiko Fujii, Takaaki Takeda, 4D2U Project, National Astronomical Observatory of Japan)

    Astronomers have developed a new model for simulating how clusters of baby stars form and evolve, helping to explain how bubbles of ionized gas are created away from the heart of a galaxy.

    Stellar nurseries often start in clouds of cold hydrogen gas, but the brightest and most massive of these newborn stars ionize the surrounding gas, making it too hot to allow new stars to form. Now scientists think that massive stars scattered by gravitational interactions inside these star-forming regions can punch a hole in the dense molecular gas in the central region to help off-center ionized bubbles get started, according to a statement (opens in new tab) from the National Astronomical Observatory of Japan (NAOJ).

    The theory comes from the work of a research team — led by Michiko Fujii, an astronomer at the University of Tokyo — that spent two years developing a simulation code to accurately reproduce the motions of individual stars. Then, the researchers applied it to mimic the real-life Orion Nebula, which sports an off-center bubble of gas, enlisting in the process the world’s most powerful supercomputer dedicated to astronomy simulations, called ATERUI II.

    “The simulations show that massive, bright, young stars can be ejected from the cluster through gravitational interactions with other stars,” Yoshito Shimajiri, a research team member at the NAOJ, which operates ATERUI II, said in the statement.

    And when these massive stars are kicked out of their nursery cluster, they can punch through dense molecular cloud, only partially ionizing the gas and allowing star formation to continue. The star’s own fate depends on just how big a kick it experienced.

    “Some of these ejected stars run away, never to return,” added Kohei Hattori, another NAOJ researcher who performed part of the analysis. “In other cases, like what is observed in the Orion Nebula, a massive star can be thrown a distance from the cluster, where it initiates an ionized bubble, and then fall back into the cluster.”

    The researchers propose that for the Orion Nebula, the bubble-blowing ejection likely occurred about 100,000 to 200,000 years ago.

    The research could be scaled up to provide insight into much larger groups of stars, the scientists hope, by incorporating still more processing power into the model.

    “This simulation is not the limit of our simulation code,” Fujii said in the statement. “Next we want to undertake the first star-by-star star-cluster formation simulation of globular clusters, which are 100 times more massive than the star cluster we simulated in this study.”

    A study describing the team’s work was published June 8 in the journal MNRAS.

    See the full article here .

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  • richardmitnick 4:43 pm on June 14, 2022 Permalink | Reply
    Tags: " 'Dark' black hole wandering the Milky Way may be the smallest yet detected", , , , , , space.com   

    From SPACE.com : ” ‘Dark’ black hole wandering the Milky Way may be the smallest yet detected” 

    From SPACE.com

    6.13.22
    Keith Cooper

    The stellar-mass black hole is likely one of 100 million solitary black holes in the Milky Way, scientists said.

    1
    Artist’s illustration of a black hole drifting through the Milky Way. (Image credit: FECYT, IAC)

    A rogue black hole wandering the space lanes of our Milky Way galaxy alone could be the smallest black hole yet found, according to one estimate of its mass.

    Earlier this year, astronomers led by Kailash Sahu of the Space Telescope Science Institute in Baltimore, Maryland, announced the discovery of the first known isolated stellar-mass black hole.

    The black hole is 5,000 light-years away and was discovered thanks to the power of its gravity to act as a gravitational lens, magnifying the light of a background star 19,000 light-years away. It was initially spotted by two ground-based surveys, the Polish-led Optical Gravitational Lensing Experiment (OGLE) which mostly uses the Las Campanas Observatory in Chile, and the Microlensing Observations in Astrophysics (MOA) project at the Mount John University Observatory in New Zealand.

    1
    The Mount John University Observatory in New Zealand. Credit: geekgirltakingpics

    Sahu’s team used the Hubble Space Telescope to follow up on the discovery, and the degree of gravitational lensing allowed them to conclude that the black hole has a mass about 7.1 times greater than the sun’s mass.

    However, a second team has now come forward with a different mass calculation. The group, led by Casey Lam of the University of California-Berkeley, concluded that the object has a mass between 1.6 and 4.4 times the mass of the sun. If correct, then this could have intriguing implications.

    Stellar-mass black holes are the product of the supernovae of stars with masses 20 times greater than the Sun. On the other hand, when stars with between 8 and 20 solar masses go supernovae, they leave behind a neutron star instead.

    Neutron stars can theoretically have masses up to about 2.3 solar masses. Observations of stellar-mass black holes detectable in binary systems have not turned up any with less than 5 solar masses, creating a gap between the most massive neutron stars and the least massive black holes. If the black hole is at the upper end of Lam’s mass range, it would help plug this gap. (Several candidate gravitational-wave events have also been detected involving objects that fall into this mass gap.)

    “Whatever it is, the object is the first dark stellar remnant discovered wandering through the galaxy unaccompanied by another star,” said Lam in a NASA statement [see “Hubble Determines Mass of Isolated Black Hole Roaming Our Milky Way Galaxy” June 10, 2022 blog post].

    3
    A composite image captured by the Hubble Space Telescope shows the change in brightness of a star caused by a foreground black hole drifting in front of it. The apparent brightening of the background star is caused by gravitational lensing. (Image credit: NASA, ESA, Kailash Sahu (STScI) IMAGE PROCESSING: Joseph DePasquale (STScI))

    Even though stars with more than 20 solar masses account for just 0.1% of all the stars in the Milky Way, there are so many stars in the Milky Way (an estimated 100–200 billion), and the Milky Way is so old (approximately 13 billion years) that there should now be 100 million or more stellar-mass black holes in our galaxy.

    Many of these are found in binary systems, where their presence is evident from their gravitational pull on their companion star and their accretion of matter from their neighbor. One has even been found inside a star cluster, NGC 1850 in the Large Magellanic Cloud. However, many others will be wandering between the stars, going unnoticed until a chance alignment with a background star means we spot them creating a gravitational lens.

    This discovery is just the tip of the iceberg. NASA’s Nancy Grace Roman Space Telescope, which is planned for launch in 2027, will survey large swathes of the Milky Way and is expected to identify several thousand microlensing events, many of which could be black holes.

    Science papers:
    Sahu team STScI

    Lam’s team STScI

    See the full article here .

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  • richardmitnick 8:08 am on May 14, 2022 Permalink | Reply
    Tags: "World's most powerful heavy-ion collider to go online this week", , Physicists are excited by the FRIB because it may provide a much clearer view of the landscape of possible atomic isotopes., , space.com, , The new accelerator will create new exotic atoms and reveal how stars and supernovas forge the elements that make up our universe., The new FRIB accelerator will grant researchers access to more than 1000 new isotopes., The new reactor will fire two heavy atomic nuclei at each other splitting them apart in ways that enable scientists to study what glues them together and how rare atomic isotopes are structured., The world's most powerful heavy-ion accelerator is finally completed researchers announced May 2 2022.   

    From The Michigan State University via SPACE.com : “World’s most powerful heavy-ion collider to go online this week” 

    Michigan State Bloc

    From The Michigan State University

    via

    SPACE.com

    5.13.22
    Ben Turner

    It will allow scientists to peer into the inner workings of supernovas.

    The world’s most powerful heavy-ion accelerator — which will create new exotic atoms and reveal how stars and supernovas forge the elements that make up our universe — is finally completed, researchers announced May 2, 2022.

    Experiments at the $730 million Facility for Rare Isotope Beams (FRIB) at The Michigan State University are slated to start this week. Once online, the new reactor will fire two heavy atomic nuclei at each other, splitting them apart in ways that enable scientists to study what glues them together and how rare atomic isotopes — versions of chemical elements with different numbers of neutrons in their nuclei — are structured.

    While past heavy-ion accelerators (such as the National Superconducting Cyclotron Laboratory, MSU’s previous accelerator) enabled scientists to catch glimpses of exotic atoms, they didn’t produce them at a fast enough rate to make detailed study possible.

    The new FRIB accelerator will grant researchers access to more than 1000 new isotopes, giving them fresh insight into new cancer treatments, radiometric dating of ancient materials, and nuclear security, according to MSU scientists.

    “FRIB will be the core piece of our nation’s research infrastructure,” Thomas Glasmacher, the FRIB Laboratory Director, said at the ribbon-cutting ceremony, according to the Lansing State Journal. “More than 1,600 scientists are eager to come here because we will be the best, most powerful superconducting heavy-ion linear accelerator.”


    The Facility for Rare Isotope Beams (FRIB) at MSU.

    Physicists are excited by the FRIB because it may provide a much clearer view of the landscape of possible atomic isotopes. Right now, physicists have a good idea of what holds nuclei together — one of the four fundamental forces called the strong force — and have made a good number of models to predict what some unobserved atomic nuclei might look like. But nuclei are complex and can glue together in surprising ways, making the models far too simplistic. A number of the nuclei predicted by the models, for instance, might not hold together well enough to exist.

    Other questions that scientists hope to answer include how well the most stable isotopes are described by current models, and how elements heavier than iron and nickel (the latter two being the heaviest elements made by nuclear fusion in stars) are formed through radioactive beta decay. Beta decay takes place when an atomic nucleus absorbs a neutron or when one of its neutrons becomes a proton, making the nucleus unstable.

    Scientists believe that elements formed by beta decay are typically made as byproducts of supernovas or the collisions of neutron stars, but until now haven’t been able to check, or to study what kinds of elements are produced and in what proportions during these celestial processes. But FRIB will provide a way to finally test these suppositions, as one if its accelerators speeds up individual isotopes before smashing them into a target, enabling scientists to simulate the collisions that take place inside stars and supernovas.

    To produce isotopes for study, physicists will select atoms of a very heavy element, such as uranium, before stripping them of their electrons to turn them into ions. Then they will launch them down a 1,476-foot-long (450 meters) pipe more than halfway to the speed of light. At the end of the pipe, the beam of ions will hit a graphite wheel, splintering into smaller neutron-proton combinations, or isotopes.

    By steering these freshly made isotopes through a series of finely adjustable magnets, the physicists will be able to carefully select which isotope they want to fire into one of the facility’s experimental halls for further study. FRIB will eventually be joined by another atom smasher, the $3.27 billion Facility for Antiproton and Ion Research (FAIR) currently being built in Darmstadt, Germany. The accelerator, set for completion in 2027, has been designed to make antimatter as well as matter, and will be able to store the nuclei it produces for longer timeframes than FRIB.

    See the full article here .


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    Michigan State Campus

    The Michigan State University is a public research university located in East Lansing, Michigan, United States. Michigan State University was founded in 1855 and became the nation’s first land-grant institution under the Morrill Act of 1862, serving as a model for future land-grant universities.

    The university was founded as the Agricultural College of the State of Michigan, one of the country’s first institutions of higher education to teach scientific agriculture. After the introduction of the Morrill Act, the college became coeducational and expanded its curriculum beyond agriculture. Today, Michigan State University is one of the largest universities in the United States (in terms of enrollment) and has approximately 634,300 living alumni worldwide.

    U.S. News & World Report ranks its graduate programs the best in the U.S. in elementary teacher’s education, secondary teacher’s education, industrial and organizational psychology, rehabilitation counseling, African history (tied), supply chain logistics and nuclear physics in 2019. Michigan State University pioneered the studies of packaging, hospitality business, supply chain management, and communication sciences. Michigan State University is a member of the Association of American Universities and is classified among “R1: Doctoral Universities – Very high research activity”. The university’s campus houses the National Superconducting Cyclotron Laboratory, the W. J. Beal Botanical Garden, the Abrams Planetarium, the Wharton Center for Performing Arts, the Eli and Edythe Broad Art Museum, the the Facility for Rare Isotope Beams, and the country’s largest residence hall system.

    Research

    The university has a long history of academic research and innovation. In 1877, botany professor William J. Beal performed the first documented genetic crosses to produce hybrid corn, which led to increased yields. Michigan State University dairy professor G. Malcolm Trout improved the process for the homogenization of milk in the 1930s, making it more commercially viable. In the 1960s, Michigan State University scientists developed cisplatin, a leading cancer fighting drug, and followed that work with the derivative, carboplatin. Albert Fert, an Adjunct professor at Michigan State University, was awarded the 2007 Nobel Prize in Physics together with Peter Grünberg.

    Today Michigan State University continues its research with facilities such as the Department of Energy -sponsored Plant Research Laboratory and a particle accelerator called the National Superconducting Cyclotron Laboratory [below]. The Department of Energy Office of Science named Michigan State University as the site for the Facility for Rare Isotope Beams (FRIB). The $730 million facility will attract top researchers from around the world to conduct experiments in basic nuclear science, astrophysics, and applications of isotopes to other fields.

    Michigan State University FRIB [Facility for Rare Isotope Beams] .

    In 2004, scientists at the Cyclotron produced and observed a new isotope of the element germanium, called Ge-60 In that same year, Michigan State University, in consortium with the University of North Carolina at Chapel Hill and the government of Brazil, broke ground on the 4.1-meter Southern Astrophysical Research Telescope (SOAR) in the Andes Mountains of Chile.


    The consortium telescope will allow the Physics & Astronomy department to study galaxy formation and origins. Since 1999, MSU has been part of a consortium called the Michigan Life Sciences Corridor, which aims to develop biotechnology research in the State of Michigan. Finally, the College of Communication Arts and Sciences’ Quello Center researches issues of information and communication management.


    The Michigan State University Spartans compete in the NCAA Division I Big Ten Conference. Michigan State Spartans football won the Rose Bowl Game in 1954, 1956, 1988 and 2014, and the university claims a total of six national football championships. Spartans men’s basketball won the NCAA National Championship in 1979 and 2000 and has attained the Final Four eight times since the 1998–1999 season. Spartans ice hockey won NCAA national titles in 1966, 1986 and 2007. The women’s cross country team was named Big Ten champions in 2019. In the fall of 2019, MSU student-athletes posted all-time highs for graduation success rates and federal graduation rates, according to NCAA statistics.

     
  • richardmitnick 3:06 pm on November 14, 2021 Permalink | Reply
    Tags: "China is building a new ship for sea launches to space", space.com   

    From SPACE.com : “China is building a new ship for sea launches to space” 

    From SPACE.com

    11.14.21
    Andrew Jones

    1
    A Chinese Long March 11 rocket astands atop country’s sea-based platform De Bo 3 in the Yellow Sea ahead of a Sept. 15, 2020 launch. (Image credit: China Aerospace Science and Technology Corporation [中国航天科技集团公司](CN))

    China is building a specially designed ship for launching rockets into space from the seas in an effort to boost its capacity to launch satellites and recover rocket stages.

    The 533 feet (162.5 meters) long, 131 feet (40 meters) wide “New-type rocket launching vessel” is being constructed for use with the new China Oriental Spaceport at Haiyang, Shandong province on the Eastern coast.

    The new ship is expected to enter service in 2022. It will feature integrated launch support equipment and be capable of facilitating launches of the Long March 11, larger commercial “Smart Dragon” rockets and, in the future, liquid propellant rockets, according to the social media channel for the spaceport.

    The vessel could also in the future be used for the recovery of first stages, possibly in the same way as SpaceX’s autonomous spaceport drone ships provide a landing platform for Falcon 9 and Falcon Heavy rocket first stages.

    China has already conducted two sea launches of Long March 11 solid rockets from the Yellow Sea using converted barges, with the most recent launch taking place in September 2020. These missions made China only the third country to perform a sea launch, following the U.S. and Russia.

    China’s main space contractor stated at the start of the year that it planned two to three sea launches of the Long March 11, but none have taken place so far. It is not known if plans for the new ship are related to the apparent delays.

    The ship will help boost the rate at which China can launch from the sea and ease the pressure on China’s four main launch centers.

    So far in 2021 China has already launched 41 times, setting a new national record for orbital launches in a calendar year, leading the U.S. which has 39 launches to date, including Rocket Lab launches from New Zealand.

    With new commercial companies emerging and major constellation plans in the works, along with preparations for major space station missions, the sea launch option will provide more routes to orbit.

    Launching from the sea holds promises other advantages for China. Flexible positioning of the launch site means it is easier to choose a flight path which doesn’t fly over other countries and makes sure spent rocket stages and other debris fall into the sea rather than on land. Debris from launches from China’s inland sites fall to ground rather than the sea, and sometimes land close to populated areas.

    A mobile sea platform also allows launches closer to the equator. The greater rotational speed of the Earth near the equator means lower fuel requirements to achieve orbit.

    The China Oriental Seaport (sometimes instead called the “China Eastern Seaport”) project is being led by the China Academy of Launch Vehicle Technology (CALT), the main rocket maker under China’s giant state-owned space contractor, CASC, in cooperation with the government of Haiyang city.

    The Haiyang base will also have the capacity for rocket assembly and testing, and produce up to 20 solid rockets per year. Future plans will enable the site to also produce more complex liquid propellant rockets.

    China Rocket Co. Ltd., a commercial spinoff from CALT, is developing the “Smart Dragon” series of solid rockets. Smart Dragon 3 is expected to launch for the first time in 2022 and, at 102 (31 meters) long, will be much larger than the 64 feet (19.5 meters) long Smart Dragon 1 which launched for the first time in 2019.

    China Rocket has also signed a contract for launches from Haiyang and Smart Dragon 3 will be capable of launching from the sea.

    See the full article here .

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  • richardmitnick 3:38 pm on July 30, 2021 Permalink | Reply
    Tags: "Why does the Milky Way have spiral arms? New Gaia data are helping solve the puzzle", , , , , GAIA Early Data Release 3 (EDR3), New data from the star-mapping Gaia satellite are helping scientists unlock the mystery of our Milky Way galaxy's spiral arms., Our galaxy also possesses two less pronounced arms-or spurs-called the 'Sagittarius arm" and the "Local Arm" (which passes close to the sun)., Since the 1950s astronomers have known the Milky Waylooks like a spiral with several dense streams of stars and dust emanating from the galactic center winding through the galactic disc., , space.com, The European Gaia mission keeps uncovering the mysteries of the Milky Way., The Milky Way is known to have two main spiral arms: the "Perseus arm" and the "Scutum-Centaurus arm"., The short "Local arm" appeared much longer than the previous models expected., We derive the distance of the stars from a measure called the parallax-20% better with the latest release., When the researchers compared their galaxy map to previous models they found that the Perseus arm lies further away from the center of the galaxy in the studied region.   

    From European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) GAIA Mission (EU) via SPACE.com : “Why does the Milky Way have spiral arms? New Gaia data are helping solve the puzzle” 

    ESA/GAIA satellite

    From European Space Agency [Agence spatiale européenne][Europäische Weltraumorganisation](EU) GAIA Mission (EU)

    via

    SPACE.com

    7.30.21
    Tereza Pultarova

    The European Gaia mission keeps uncovering the mysteries of the Milky Way.

    New data from the star-mapping Gaia satellite are helping scientists unlock the mystery of our Milky Way galaxy’s spiral arms.

    Recently published studies exploring the Early Data Release 3 (EDR3), a batch of observations made available to the scientific community last December, reveal the spiral structure of our galaxy with a greater precision and detail than was possible before.

    Since the 1950s astronomers have known that our galaxy-the Milky Way-looks like a spiral with several dense streams of stars and dust emanating from the galactic center winding through the galactic disc and dissolving around its edges. However, scientists have struggled to understand how many of these streams there are and what created them.

    “The problem with our galaxy is that we are inside its disc and therefore it’s very difficult to understand the structure as a whole,” Eleonora Zari, a scientist at the MPG Institute for Astronomy [MPG Institut für Astronomie](DE) in Heidelberg, Germany, and author of one of the new papers, told Space.com. “It’s like being in a forest and looking around. At some point, the trees are in front of each other. Plus the forest is a bit foggy, so you really can’t see what the whole forest looks like.”

    The European Space Agency’s (ESA) Gaia mission has been mapping the Milky Way since 2014, measuring the precise positions and distances from Earth of nearly two billion stars. The first two batches of data acquired by the spacecraft, which were released to the scientific community in 2016 and 2018, have revolutionized the study of our galaxy. In addition to the fixed positions, the spacecraft also measures how fast stars move in three-dimensional space, allowing astronomers to model the evolution of the Milky Way in the past as well as into the future.

    The latest data release, EDR3, improves the accuracy of the previous data sets. And it’s this precision that is enabling astronomers to disentangle the spiral arms from the rest of the stars in the galactic disc with better precision.

    Where are the arms?

    “We derive the distance of the stars from a measure called the parallax,” Zari said. “And this parallax measurement is 20% better with the latest release. That means that stars that previously we may have seen as part of the same structure now clearly belong to different structures.”

    Parallax is a star’s apparent movement against the background of more distant stars as Earth revolves around the sun. By measuring the change in the angle between the star and Earth from two opposite points in the planet’s orbit, astronomers can calculate the distance of the star using simple trigonometry.

    In one new paper [Astronomy & Astrophysics], Zari and her colleagues looked at concentrations of hot bright blue stars, called the OBA-type stars, in the Milky Way’s disc. In areas where they could see a higher-than-average concentration of these stars, they could assume the existence of a spiral arm. They then compared their analysis with previously developed models of the galaxy.

    “The position of the spiral arms is different and also the strength of the spiral arms, how bright they are, is different,” Zari said.

    The Milky Way is known to have two main spiral arms: the “Perseus arm” and the “Scutum-Centaurus arm”. Our galaxy also possesses two less pronounced arms-or spurs-called the ‘Sagittarius arm” and the “Local Arm” (which passes close to the sun).

    But in Zari’s study, the difference between the arms doesn’t seem so obvious.

    “The Perseus arm seems less bright, and instead the Local arm is more prominent,” she said. “Aso the other two arms — Sagittarius and Scutum Centaurus — at least in my study, they seem to have about the same brightness.”

    Zari’s colleague Eloisa Poggio looked at concentrations of 600,000 young stars to determine the precise position of the spiral arms. Young stars are especially valuable when studying the spiral arms, Poggio explained, because spiral arms, with their dense concentration of dust and gas, are believed to be where the majority of stars form.

    “We calculated, for each position in the disc, whether that region was more or less populated with respect to the average,” Poggio told Space.com. “Using that approach, we were able to construct a map of the spiral arms in the region that Gaia maps, that is about 16,000 light-years around the sun.”

    When the researchers compared their galaxy map to previous models they found that the Perseus arm lies further away from the center of the galaxy in the studied region. The short Local arm appeared much longer than the previous models expected.

    How do the arms form?

    Astronomers are also still speculating about the origin of those arms and their longevity. Some earlier theories proposed that the shape of the arms is somehow fixed and spins around the galactic center over a long period of time while individual stars, orbiting at their own velocities, move in and out of this shape.

    This so-called density wave theory, however, is being disputed by the latest findings enabled by the Gaia mission. Many scientists now think that the spiral arms might not be fixed at all. Instead, they might form temporarily, as a result of the rotation of the galactic disc, and later dissolve and reform again in a different configuration.

    To find which theory is correct, Alfred Castro, of the Leiden University [Universiteit Leiden] (NL), in the Netherlands, looked at so-called open clusters [On the Milky Way spiral arms from open clusters in Gaia EDR3], groups of thousands of young stars born from the same cloud of gas and dust. Due to their young age, these stars are still close to their birth place, that is within the spiral arms. If the newer theories were correct, the amount of younger open clusters in the spiral arms would be higher than the amount of older open clusters, Castro speculated. And that’s exactly what the data showed.

    “I saw in the data that the spiral structure appears to contain the younger population of stars but disappears if you look at the older stars,” Castro told Space.com. “We see that the rotation rate of the shape is more or less similar to the rotation rate of the stars and varies with the radius to the galactic center. The shape and the stars can’t be decoupled, and that means we don’t have a global shape, which would be the spiral arms, and then the stars moving in and out of them as the density wave theory suggests.”

    According to Castro’s analysis, the spiral arms may exist for about 80 to 100 million years, a small fraction of time in the 13-billion-year life of our galaxy.

    What gave the Milky Way the spiral arms?

    In the future, Poggio hopes, scientists might be able to find out why those spiral arms in the Milky Way exist in the first place. While some theories expect this swirl of stellar streams may have been born after another, smaller galaxy crashed into the Milky Way, others believe it came to existence naturally as a result of the rotation of the galactic disc.

    “We expect that we would see different signatures in the motion of the stars if the spiral arms were caused by an external impact,” Poggio said. “Future Gaia data releases will give us more information about the motion of stars in a greater portion of the galactic disc, and we hope we might be able to find something there.”

    The next batch of Gaia data, the full Data Release 3, is expected to be made available to scientists worldwide in about mid-2022. Gaia, one of the most productive missions in history (measured by the number of scientific papers it produces), will continue scanning the sky until 2025. The vast catalogues of stellar positions, motions and velocities it creates will keep astronomers busy for decades to come.

    The papers by Poggio, Castro and Zari were published in the journal Astronomy and Astrophysics in July.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Objective
    A global space astrometry mission, Gaia will make the largest, most precise three-dimensional map of our Galaxy by surveying more than a thousand million stars.

    Mission
    Gaia will monitor each of its target stars about 70 times over a five-year period. It will precisely chart their positions, distances, movements, and changes in brightness. It is expected to discover hundreds of thousands of new celestial objects, such as extra-solar planets and brown dwarfs, and observe hundreds of thousands of asteroids within our own Solar System. The mission will also study about 500 000 distant quasars and will provide stringent new tests of Albert Einstein’s General Theory of Relativity.

    Gaia will create an extraordinarily precise three-dimensional map of more than a thousand million stars throughout our Galaxy and beyond, mapping their motions, luminosity, temperature and composition. This huge stellar census will provide the data needed to tackle an enormous range of important problems related to the origin, structure and evolutionary history of our Galaxy.

    For example, Gaia will identify which stars are relics from smaller galaxies long ago ‘swallowed’ by the Milky Way. By watching for the large-scale motion of stars in our Galaxy, it will also probe the distribution of dark matter, the invisible substance thought to hold our Galaxy together.

    Gaia will achieve its goals by repeatedly measuring the positions of all objects down to magnitude 20 (about 400 000 times fainter than can be seen with the naked eye).

    For all objects brighter than magnitude 15 (4000 times fainter than the naked eye limit), Gaia will measure their positions to an accuracy of 24 microarcseconds. This is comparable to measuring the diameter of a human hair at a distance of 1000 km.

    It will allow the nearest stars to have their distances measured to the extraordinary accuracy of 0.001%. Even stars near the Galactic centre, some 30 000 light-years away, will have their distances measured to within an accuracy of 20%.

    The vast catalogue of celestial objects expected from Gaia’s scientific haul will not only benefit studies of our own Solar System and Galaxy, but also the fundamental physics that underpins our entire Universe.

     
  • richardmitnick 6:44 pm on January 31, 2021 Permalink | Reply
    Tags: "We may have found the most powerful particle accelerator in the galaxy", A source of gamma rays exceeding 200 TeV called HAWC J1825-134., , , , Charged particles traveling through interstellar space respond to our galaxy's magnetic field., , , Gamma rays shoot straight-line through the galaxy allowing us to directly pinpoint their origins., , space.com, When cosmic rays accidentally strike a cloud of interstellar gas they can emit gamma rays.   

    From SPACE.com: “We may have found the most powerful particle accelerator in the galaxy” 

    From SPACE.com

    1.29.21
    Paul Sutter

    And it’s quite a surprising source.

    1
    This image, created using data from the European Space Agency’s Herschel and Planck space telescopes, shows a piece of the Taurus Molecular Cloud.© ESA/Herschel/Planck; J. D. Soler, MPIA.

    ESA/Herschel spacecraft active from 2009 to 2013.

    ESA/Planck 2009 to 2013

    Astronomers have long wondered where high-energy cosmic rays come from within our galaxy.

    And now, new observations with the High Altitude Water Cherenkov Experiment (HAWC) observatory reveal an unlikely candidate: an otherwise mundane giant molecular cloud.

    HAWC High Altitude Čerenkov Experiment, a US Mexico Europe collaboration located on the flanks of the Sierra Negra volcano in the Mexican state of Puebla at an altitude of 4100 meters(13,500ft), at WikiMiniAtlas 18°59′41″N 97°18′30.6″W. searches for cosmic rays.

    Taking the knee

    Cosmic rays are not rays at all but rather tiny particles cruising through the universe at nearly the speed of light. They can be made of electrons, protons or even ions of heavier elements. They are created in all sorts of high-energy processes throughout the cosmos, from supernova explosions to the mergers of stars to the final insane moments when gas gets sucked up by a black hole.

    Cosmic rays come in all sorts of energies, and generally speaking the higher-energy cosmic rays are rarer than their low-energy relatives. This relationship changes in a very slight way at a particular energy — 10^15 electron-volts — which is called the “knee.” The electron-volt, or eV, is just the way that particle physicists enjoy measuring energy levels. For comparison, the most powerful particle collider on Earth, the Large Hadron Collider, can achieve 13 X 10^12 eV, which is often denoted as 13 tera electron-volts, or 13 TeV.

    CERN (CH) LHC Map

    Above an energy of 10^15 eV, cosmic rays are much rarer than you would expect. This has led astronomers to believe that any cosmic rays at this energy level and higher come from outside the galaxy, while processes within the Milky Way are capable of producing cosmic rays up to and including 10^15 eV.

    For those of you keeping score at home, whatever is creating these cosmic rays would be in the “peta” range of Greek prefixes, and therefore over 1,000 times more powerful than our best particle accelerators — natural “PeVatrons” roaming the galaxy.

    A hawkeyed sleuth

    The mission is simple: find the source of PeV-scale cosmic rays in the Milky Way. But despite their energies, it’s hard to pinpoint their origins. That’s because cosmic rays are made of charged particles, and charged particles traveling through interstellar space respond to our galaxy’s magnetic field. Thus when you see a high-energy cosmic ray coming from a particular direction in the sky, you actually have no idea where it truly came from — its path has bent and curved over the course of its journey to Earth.

    But instead of hunting for cosmic rays directly, we can search for some of their relatives. When cosmic rays accidentally strike a cloud of interstellar gas, they can emit gamma rays, a high-energy form of radiation. These gamma rays shoot straight-line through the galaxy, allowing us to directly pinpoint their origins.

    Cosmic rays produced by high-energy astrophysics sources (ASPERA collaboration – AStroParticle ERAnet).

    So if we see a source of strong gamma-ray emission, we can look for nearby sources of PeV cosmic rays.

    This was the method employed by a team of researchers using HAWC, which is located on the Sierra Negra Volcano of south-central Mexico. HAWC “stares” up at the sky with a series of tanks filled with ultra-pure water. When high-energy particles or radiation enter the tanks, they emit a flash of blue light, allowing astronomers to trace back the source onto the sky.

    Detailed in a paper recently appearing in The Astrophysical Journal Letters, the astronomers found a source of gamma rays exceeding 200 TeV, which could only be created by even more powerful cosmic rays — the kinds of cosmic rays that reach up into the PeV scale. The source, called HAWC J1825-134, lies roughly in the direction of the galactic center. HAWC J1825-134 appears to us as a bright blotch of gamma rays, illuminated by some unknown fount of cosmic rays — perhaps the most powerful known source of cosmic rays in the Milky Way.

    An unlikely heavyweight

    A few of the usual suspect sources of high-energy cosmic rays sit within a few thousand light-years of HAWC J1825-134, but none of them can easily explain the signal.

    For example, the galactic center itself is a known generator of intense cosmic ray action, but it’s way too far away from HAWC J1825-134, so it has no bearing on this measurement.

    There are some supernova remnants, and supernovae sure are powerful. But all the supernovae in the region of HAWC J1825-134 went off ages ago — far too long in the past to be creating these high-energy cosmic rays now.

    Pulsars — the rapidly spinning dense remnant cores of massive stars — also produce copious amounts of cosmic rays. But those too sit too far away from the source of gamma rays — the energies of the electrons and protons coming off the pulsar just aren’t punchy enough to travel the thousands of light-years to the location of the gamma ray emission.

    Surprisingly, the source of these record-breaking cosmic rays appears to be none other than a giant molecular cloud. These clouds are giant, lumbering brutes, filled with dust and gas, that roam the galaxy. They occasionally contract in on themselves and turn into stars, but otherwise they can remain cool and loose for billions of years. Not causing anyone any serious threat — and barely even noticeable unless you have good infrared telescopes — they are the last place you would expect to find such insanely high energies.

    Located within the cloud complex is a cluster of newborn stars, but even the crankiest and loudest of baby stars aren’t thought to be powerful enough to launch cosmic rays like this. The researchers themselves admit that they don’t know how this cloud is doing it, but somehow, when nobody was paying attention, it generated some of the most powerful particles in the entire galaxy.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 11:15 am on January 3, 2021 Permalink | Reply
    Tags: "The Milky Way is probably full of dead civilizations", , , , Carl Sagan's "Cosmos" miniseries, , , space.com, We are likely a frontier civilization in terms of galactic geography and relative latecomers to the self-aware Milky Way inhabitant scene.   

    From SPACE.com: “The Milky Way is probably full of dead civilizations” 

    From SPACE.com

    1.2.21
    Rafi Letzter

    1
    © European Southern Observatory.

    That’s the takeaway of a new study, published Dec. 14 to the arXiv database [A Statistical Estimation of the Occurrence of Extraterrestrial Intelligence in the Milky Way Galaxy], which used modern astronomy and statistical modeling to map the emergence and death of intelligent life in time and space across the Milky Way. Their results amount to a more precise 2020 update of a famous equation that Search for Extraterrestrial Intelligence founder Frank Drake wrote in 1961.

    Frank Drake with his Drake Equation. Credit Frank Drake.

    The Drake equation, popularized by physicist Carl Sagan in his Cosmos miniseries, relied on a number of mystery variables — like the prevalence of planets in the universe, then an open question.

    This new paper, authored by three Caltech physicists and one high school student, is much more practical. It says where and when life is most likely to occur in the Milky Way, and identifies the most important factor affecting its prevalence: intelligent creatures’ tendency toward self-annihilation.

    “Since Carl Sagan’s time, there’s been lots of research,” said study co-author Jonathan H. Jiang, an astrophysicist at NASA’s Jet Propulsion Laboratory at Caltech. “Especially since the Hubble Space Telescope and Kepler Space Telescope, we have lots of knowledge about the densities [of gas and stars] in the Milky Way galaxy and star formation rates and exoplanet formation … and the occurrence rate of supernova explosions. We actually know some of the numbers [that were mysteries at the time of the famous Cosmos episode].”

    The authors looked at a range of factors presumed to influence the development of intelligent life, such as the prevalence of sun like stars harboring Earth-like planets; the frequency of deadly, radiation-blasting supernovas; the probability of and time necessary for intelligent life to evolve if conditions are right; and the possible tendency of advanced civilizations to destroy themselves.

    Modeling the evolution of the Milky Way over time with those factors in mind, they found that the probability of life emerging based on known factors peaked about 13,000 light-years from the galactic center and 8 billion years after the galaxy formed. Earth, by comparison, is about 25,000 light-years from the galactic center, and human civilization arose on the planet’s surface about 13.5 billion years after the Milky Way formed (though simple life emerged soon after the planet formed.)

    In other words, we’re likely a frontier civilization in terms of galactic geography and relative latecomers to the self-aware Milky Way inhabitant scene. But, assuming life does arise reasonably often and eventually becomes intelligent, there are probably other civilizations out there — mostly clustered around that 13,000-light-year band, mostly due to the prevalence of sunlike stars there.

    2
    A figure from the paper plots the age of the Milky Way in billions of years (y axis) against distance from the galactic center (x axis), finding a hotspot for civilization 8 billion years after the galaxy formed and 13,000 light years from the galactic center. Credit: Cai et al.

    Most of these other civilizations that still exist in the galaxy today are likely young, due to the probability that intelligent life is fairly likely to eradicate itself over long timescales. Even if the galaxy reached its civilizational peak more than 5 billion years ago, most of the civilizations that were around then have likely self-annihilated, the researchers found .

    This last bit is the most uncertain variable in the paper; how often do civilizations kill themselves? But it’s also the most important in determining how widespread civilization is, the researchers found. Even an extraordinarily low chance of a given civilization wiping itself out in any given century — say, via nuclear holocaust or runaway climate change — would mean that the overwhelming majority of peak Milky Way civilizations are already gone.

    The above paper has been submitted to a journal for publication and is awaiting peer review.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

     
  • richardmitnick 11:54 am on December 18, 2019 Permalink | Reply
    Tags: "The Asteroids Might Remember a Forgotten Giant Planet", , , , , , , space.com   

    From Ohio State University via SPACE.com: “The Asteroids Might Remember a Forgotten Giant Planet” 

    OSU

    From Ohio State University

    space-dot-com logo

    SPACE.com

    12.18.19
    Paul Sutter-
    Paul M. Sutter is an astrophysicist at The Ohio State University

    We have much to learn from the rocks of the asteroid belt.

    1
    An artist’s illustration of the asteroid belt.(Image: © ESA/ATG medialab)

    The formation of the solar system is a deeply perplexing puzzle. We’re left with clues all over the place: the positions and sizes of the planets, the members of the asteroid belt, Kuiper Belt, and Oort Cloud and the populations of moons around the planets.

    The inner Solar System, from the Sun to Jupiter. Also includes the asteroid belt (the white donut-shaped cloud), the Hildas (the orange “triangle” just inside the orbit of Jupiter), the Jupiter trojans (green), and the near-Earth asteroids. The group that leads Jupiter are called the “Greeks” and the trailing group are called the “Trojans” (Murray and Dermott, Solar System Dynamics, pg. 107)
    This image is based on data found in the en:JPL DE-405 ephemeris, and the en:Minor Planet Center database of asteroids (etc) published 2006 Jul 6. The image is looking down on the en:ecliptic plane as would have been seen on 2006 August 14. It was rendered by custom software written for Wikipedia. The same image without labels is also available at File:InnerSolarSystem.png. Mdf at English Wikipedia

    Kuiper Belt. Minor Planet Center

    Oort Cloud, The layout of the solar system, including the Oort Cloud, on a logarithmic scale. Credit: NASA, Universe Today


    Oort Cloud NASA

    But how did we get to this from a vague disk of gas and dust billions of years ago?

    Simulations and models lead the way, and recently researchers have turned to the asteroid belt for more help: the asteroids living closest to the sun actually preserve a memory from when the solar system was still evolving, and might even offer clues to the hypothesis that we once had five giant planets.

    Billions of years ago, our solar system was just a bunch of random gas and dust floating around as a nebula. As it collapsed, it formed a rapidly spinning merry-go-round of a flat disk around the young and hungry proto-sun. Over the course of 100 million years, that disk somehow became the planets and other smaller denizens of our home system.

    Computer simulations of the disk-to-planet process are fantastically difficult, due to all the rich and complex physics involved, but they have a few general features. The innermost worlds tend to be small and rocky, while the outermost planets tend to be big and gassy and/or icy. Plus the process of formation leads to a bunch of random junk floating around.

    Another general feature is that newborn planets tend to move quickly into resonant motion, meaning that orbits become integer multiples of each other. For example, Mars might orbit four times for every Jupiter orbit, and Jupiter might orbit twice for every turn around the sun that Saturn gets.

    And when it comes to our solar system in particular, in simulations the giant planets tend to form much closer together, and much closer to the sun, than they are today.

    So then the question becomes: Once we’ve got a batch of baby planets formed from our protostellar disk, how do we get those planets in their modern-day positions?

    It’s Nice out there

    Enter the Nice Model, named after the city in southern France where a few sun-baked researchers cooked up the idea in 2005. In the bare-bones version of the model, the too-close-for-comfort giant planets are surrounded by a disk of leftovers: tiny planetesimals that never got to play the planet game and had to hang out in the outskirts of the solar system.

    But not for long. Ever so slowly, over the course of 100 million years, the outermost giant planet (usually thought to be Neptune, but in some versions of the model it’s Uranus) drifts close to one of those leftovers. Close enough to interact gravitationally, doing a little orbital dance where the planet pulls the bit of rock inward to a smaller orbit, and in exchange sends itself farther out.

    And then that little scattered rock encounters the next planet in and does the same thing. And then it approaches Saturn and repeats the process again, going ever sunward and spreading out three of the giant planets.

    And then that plucky little planetesimal finds Jupiter, who is generally in no mood for games and doesn’t like to be told what to do. Instead of nudging the rock inward, the massive bulk of our system’s largest planet just sends that unlucky bit of debris out of the solar system altogether. That doesn’t come without a price, however; the energy needed to eject the planetesimal reduces Jupiter’s own orbit, sending it slightly closer to the sun.

    This model is able to explain in large part the modern-day positions of the planets, and how they were able to get there from their birthplaces. And since 2005, more sophisticated versions of the Nice Model have appeared, trying to explain finer details of our system’s makeup, including the possibility that we once were home to a fifth giant planet that got lost in all the gravitational reshuffling.

    Look to the asteroids

    But all versions of the Nice Model have a particular problem with the asteroid belt. All that orbital dancing in the outer system can have big impacts on the inner worlds and their own population of planetary leftovers. The on-again-off-again gravitational resonances that the outer planets experience as they migrate to and fro in the outer reaches destabilize members of the nascent asteroid belt, scattering them into all sorts of crazy orbits.

    In particular, the various versions of the Nice Model tend to send the innermost belt members (the chunks of rock within 2.5 astronomical units) into orbits with high inclination, meaning that they’re angled with respect to the rest of the solar system. (One astronomical unit, or AU, is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.) And yet, we find most asteroids are on an even keel with the major planets, so we must be getting something wrong in our models.

    Recently, a team of researchers took a more refined approach to the simulations [MNRAS], looking especially at the interactions of Jupiter and Saturn as they waltzed together in the early days of the solar system. The scientists found that during the process of planetary migration, Jupiter and Saturn approach a 5:2 resonance, meaning that Jupiter orbits five times for every two orbits of Saturn.

    Baby solar systems

    Billions of years ago, our solar system was just a bunch of random gas and dust floating around as a nebula. As it collapsed, it formed a rapidly spinning merry-go-round of a flat disk around the young and hungry proto-sun. Over the course of 100 million years, that disk somehow became the planets and other smaller denizens of our home system.

    Computer simulations of the disk-to-planet process are fantastically difficult, due to all the rich and complex physics involved, but they have a few general features. The innermost worlds tend to be small and rocky, while the outermost planets tend to be big and gassy and/or icy. Plus the process of formation leads to a bunch of random junk floating around.

    Another general feature is that newborn planets tend to move quickly into resonant motion, meaning that orbits become integer multiples of each other. For example, Mars might orbit four times for every Jupiter orbit, and Jupiter might orbit twice for every turn around the sun that Saturn gets.

    And when it comes to our solar system in particular, in simulations the giant planets tend to form much closer together, and much closer to the sun, than they are today.

    So then the question becomes: Once we’ve got a batch of baby planets formed from our protostellar disk, how do we get those planets in their modern-day positions?

    But all versions of the Nice Model have a particular problem with the asteroid belt. All that orbital dancing in the outer system can have big impacts on the inner worlds and their own population of planetary leftovers. The on-again-off-again gravitational resonances that the outer planets experience as they migrate to and fro in the outer reaches destabilize members of the nascent asteroid belt, scattering them into all sorts of crazy orbits.

    In particular, the various versions of the Nice Model tend to send the innermost belt members (the chunks of rock within 2.5 astronomical units) into orbits with high inclination, meaning that they’re angled with respect to the rest of the solar system. (One astronomical unit, or AU, is the average Earth-sun distance — about 93 million miles, or 150 million kilometers.) And yet, we find most asteroids are on an even keel with the major planets, so we must be getting something wrong in our models.

    Recently, a team of researchers took a more refined approach to the simulations, looking especially at the interactions of Jupiter and Saturn as they waltzed together in the early days of the solar system. The scientists found that during the process of planetary migration, Jupiter and Saturn approach a 5:2 resonance, meaning that Jupiter orbits five times for every two orbits of Saturn.

    They don’t stay in that resonance for long. But the details of Saturn’s orbit while near the resonance give it just the right gravitational effect on the inner system to clear away any high-inclination wannabes in the asteroid belt.

    And what about the more exotic models, like early solar systems including a fifth giant planet? It too has an effect on all the resonances, which means that the modern-day asteroid belt may actually be a fossil record, remembering what the young system was like. And the more we study those little leftover asteroids, the more we can learn about our own origins.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    The Ohio State University (OSU, commonly referred to as Ohio State) is a public research university in Columbus, Ohio. Founded in 1870 as a land-grant university and the ninth university in Ohio with the Morrill Act of 1862,[4] the university was originally known as the Ohio Agricultural and Mechanical College. The college originally focused on various agricultural and mechanical disciplines but it developed into a comprehensive university under the direction of then-Governor (later, U.S. President) Rutherford B. Hayes, and in 1878 the Ohio General Assembly passed a law changing the name to “The Ohio State University”.[5] The main campus in Columbus, Ohio, has since grown into the third-largest university campus in the United States.[6] The university also operates regional campuses in Lima, Mansfield, Marion, Newark, and Wooster.

    The university has an extensive student life program, with over 1,000 student organizations; intercollegiate, club and recreational sports programs; student media organizations and publications, fraternities and sororities; and three student governments. Ohio State athletic teams compete in Division I of the NCAA and are known as the Ohio State Buckeyes. As of the 2016 Summer Olympics, athletes from Ohio State have won 104 Olympic medals (46 gold, 35 silver, and 23 bronze). The university is a member of the Big Ten Conference for the majority of sports.

     
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