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  • richardmitnick 3:08 pm on May 9, 2017 Permalink | Reply
    Tags: , , , , Carnegie Institution For Science, , Surprise! When a brown dwarf is actually a planetary mass object   

    From Carnegie: “Surprise! When a brown dwarf is actually a planetary mass object” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    May 09, 2017
    No writer credit found

    1
    An artist’s conception of SIMP J013656.5+093347, or SIMP0136 for short, which the research team determined is a planetary like member of a 200-million-year-old group of stars called Carina-Near. Image is courtesy of NASA/JPL, slightly modified by Jonathan Gagné.

    Sometimes a brown dwarf is actually a planet—or planet-like anyway. A team led by Carnegie’s Jonathan Gagné, and including researchers from the Institute for Research on Exoplanets (iREx) at Université de Montréal, the American Museum of Natural History, and University of California San Diego, discovered that what astronomers had previously thought was one of the closest brown dwarfs to our own Sun is in fact a planetary mass object.

    Their results are published by The Astrophysical Journal Letters.

    Smaller than stars, but bigger than giant planets, brown dwarfs are too small to sustain the hydrogen fusion process that fuels stars and allows them to remain hot and bright for a long time. So after formation, brown dwarfs slowly cool down and contract over time. The contraction usually ends after a few hundred million years, although the cooling is continuous.

    “This means that the temperatures of brown dwarfs can range from as hot as stars to as cool as planets, depending on how old they are,” said the AMNH’s Jackie Faherty, a co-author on this discovery.

    The team determined that a well-studied object known as SIMP J013656.5+093347, or SIMP0136 for short, is a planetary like member of a 200-million-year-old group of stars called Carina-Near.

    Groups of similarly aged stars moving together through space are considered prime regions to search for free-floating planetary like objects, because they provide the only means of age-dating these cold and isolated worlds. Knowing the age, as well as the temperature, of a free-floating object like this is necessary to determine its mass.

    Gagné and the research team were able to demonstrate that at about 13 times the mass of Jupiter, SIMP0136 is right at the boundary that separates brown dwarf-like properties, primarily the short-lived burning of deuterium in the object’s core, from planet-like properties.

    Free-floating planetary mass objects are valuable because they are very similar to gas giant exoplanets that orbit around stars, like our own Solar System’s Jupiter or Saturn, but it is comparatively much easier to study their atmospheres. Observing the atmospheres of exoplanets found within distant star systems is challenging, because dim light emitted by those orbiting exoplanets is overwhelmed by the brightness of their host stars, which blinds the instruments that astronomers use to characterize an exoplanet’s atmospheres.

    “The implication that the well-known SIMP0136 is actually more planet-like than we previously thought will help us to better understand the atmospheres of giant planets and how they evolve,” Gagné said.

    They may be easier to study in great detail, but these free-floating worlds are still extremely hard to discover unless scientists spend a lot of time observing them at the telescope, because they can be located anywhere in the sky and they are very hard to tell apart from brown dwarfs or very small stars. For this reason, researchers have confirmed only a handful of free-floating planetary like objects so far.

    Étienne Artigau, co-author and leader of the original SIMP0136 discovery, added: “This newest addition to the very select club of free-floating planetary like objects is particularly remarkable, because we had already detected fast-evolving weather patterns on the surface of SIMP0136, back when we thought it was a brown dwarf.”

    In a field where analyzing exoplanet atmospheres is of the utmost interest, having already seen evidence of weather patterns on an easier-to-observe free-floating object that exists away from the brightness of its host star is an exciting realization.

    Other members of the research team were: Adam Burgasser and Daniella Bardalez Gagliuffi of University of California San Diego and Sandie Bouchard, Loïc Albert, David LaFrenière, and René Doyon of iREx.

    See the full article here .

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 3:01 pm on April 7, 2017 Permalink | Reply
    Tags: 'Nesting doll' minerals offer clues to Earth’s mantle dynamics, , Carnegie Institution For Science, , , Majorite mineral   

    From Carnegie: “‘Nesting doll’ minerals offer clues to Earth’s mantle dynamics” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    1
    The fragment of the metamorphic rock eclogite in which the garnet that encased the ferric-iron-rich majorite sample was found in Northern China. Credit: Yingwei Fei.

    April 07, 2017
    No writer credit found
    Reference to Person:
    Yingwei Fei

    Recovered minerals that originated in the deep mantle can give scientists a rare glimpse into the dynamic processes occurring deep inside of the Earth and into the history of the planet’s mantle layer. A team led by Yingwei Fei, a Carnegie experimental petrologist, and Cheng Xu, a field geologist from Peking University, has discovered that a rare sample of the mineral majorite originated at least 235 miles below Earth’s surface. Their findings are published by Science Advances.

    Majorite is a type of garnet formed only at depths greater than 100 miles. Fascinatingly, the majorite sample Fei’s team found in Northern China was encased inside a regular garnet—like mineralogical nesting dolls. It was brought to surface in the North China Craton, one of the oldest cratonic blocks in the world. What’s more, the majorite was rich in ferric iron, an oxidized form of iron, which is highly unusual for the mineral.

    All of these uncommon factors prompted the team to investigate the majorite’s origins.

    They used several different kinds of analytical techniques to determine the chemistry and structural characteristics of this majorite formed deep inside the Earth. In order to determine the exact depth of its origin, Carnegie’s postdoc Renbiao Tao conducted high-pressure experiments that mimicked the formation conditions of natural majorite. The team pinpointed its origin to a depth of nearly 250 miles (400 kilometers), at the bottom of the soft part of the upper mantle, called the asthenosphere, which drives plate tectonics.

    It is extremely unusual that a high-pressure majorite could survive transportation from such a depth. Adding to the strange circumstances is the fact that it was later encased by a garnet that formed at a much shallower depth of about 125 miles (200 kilometers). The nesting-doll sample’s existence required two separate geological events to explain, and these events created a time capsule that the researchers could use to better understand the Earth’s deep history.

    “This two-stage formation process offers us important clues about the mantle’s evolutionary stage at the time when the majorite was first formed,” Fei explained.

    The sample’s location and depth of origin indicate that it is a relic from the end of an era of supercontinent assembly that took place about 1.8 billion years ago. Called Columbia, the supercontinent’s formation built mountain ranges that persist today.

    “More research is needed to understand how the majorite became so oxidized, or rich in ferric iron, and what this information can tell us about mantle chemistry. We are going back to the site this summer to dig deeper trenches and hope to find fresh rocks that contain more clues to the deep mantle,” Fei added.

    This research was supported by the National Natural Science Foundation of China, the Carnegie Institution for Science, and the U.S. National Science Foundation.

    See the full article here .

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 11:44 am on March 22, 2017 Permalink | Reply
    Tags: Carnegie Institution For Science, , , Remnants of Earth’s Original Crust Found in Canada   

    From NOVA: “Remnants of Earth’s Original Crust Found in Canada” 

    PBS NOVA

    NOVA

    16 Mar 2017
    Annette Choi

    Two geologists studying North America’s oldest rocks have uncovered ancient minerals that are remnants of the Earth’s original crust which first formed more than 4.2 billion years ago.

    These rocks appear to preserve the signature of an early Earth that presumably took shape within the first few hundred million years of Earth’s history.

    Jonathan O’Neil and Richard Carlson uncovered the samples on a trek to the northeastern part of Canada to study the Canadian Shield formation, a large area of exposed continental crust underlying, centered on Hudson Bay, which was already known to contain some of the oldest parts of North America. O’Neil calls it the core or nucleus of the North American continent. “That spot on the shore of Hudson Bay has this older flavor to it, this older chemical signature.”

    1
    A view of 2.7 billion-year-old continental crust produced by the recycling of more than 4.2 billion-year-old rocks. Image credit: Alexandre Jean

    To O’Neil, an assistant professor of geology at the University of Ottawa, rocks are like books that allow geologists to study their compositions and to learn about the conditions in which they form. But as far as rock records go, the first billion years of the Earth’s history is almost completely unrepresented.

    “We’re missing basically all the crust that was present about 4.4 billion years ago. The question we’re after with our study is: what happened to it?” said Carlson, director of the Carnegie Institution for Science. “Part of the goal of this was simply to see how much crust was present before and see what that material was.”

    While most of the samples are made up of a 2.7 billion-year-old granite, O’Neil said these rocks were likely formed by the recycling of a much older crust. “The Earth is very, very good at recycling itself. It constantly recycles and remelts and reworks its own crust,” O’Neil said. He and Carlson arrived at their conclusion by determining the age of the samples using isotopic dating and then adding on the estimate of how long it would have taken for the recycled bits to have originally formed.

    O’Neil and Carlson’s estimate relies on the theory that granite forms through the reprocessing of older rocks. “That is a possibility that they form that way, but that is not the only way you can form these rocks,” said Oliver Jagoutz, an associate professor of geology at the Massachusetts Institute of Technology. “Their interpretation really strongly depends on their assumption that that is the way these granites form.

    The nature of Earth’s first crust has largely remained a mystery because there simply aren’t very many rocks that have survived the processes that can erase their signature from the geologic record. Crust is often forced back into the Earth’s interior, which then melts it down, the geologic equivalent of sending silver jewelry back into the forge. That makes it challenging for geologists to reconstruct how the original looked.

    These new findings give geologists an insight into the evolution of the oldest elements of Earth’s outer layer and how it has come to form North America. “We’re recycling extremely, extremely old crust to form our stable continent,” O’Neil said.

    See the full article here .

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    NOVA is the highest rated science series on television and the most watched documentary series on public television. It is also one of television’s most acclaimed series, having won every major television award, most of them many times over.

     
  • richardmitnick 12:10 pm on March 16, 2017 Permalink | Reply
    Tags: , , Carnegie Institution For Science, HD 106906b, Planetary evolution,   

    From UCLA: “Gigantic Jupiter-type planet reveals insights into how planets evolve” 

    UCLA bloc

    UCLA

    March 15, 2017
    Stuart Wolpert

    1
    HD 106906. No image credit

    2
    Simulated image of the HD 106906 stellar debris disk, showing a ring of rocky planet-forming material. Erika Nesvold/Carnegie Institution for Science

    An enormous young planet approximately 300 light-years from Earth has given astrophysicists a rare glimpse into planetary evolution.

    The planet, known as HD 106906b, was discovered in 2014 by a team of scientists from the U.S., the Netherlands and Italy. It is 11 times the mass of Jupiter and is extremely young by celestial standards — not more than 13 million years old, compared with our solar system’s 4.6 billion years.

    “This is such a young star; we have a snapshot of a baby star that just formed its planetary system — a rare peek at the final stage of planet formation,” said Smadar Naoz, a UCLA assistant professor of physics and astronomy, and a co-author of the study.

    Another of the planet’s unusual characteristics is its distance from its star. Astronomers believe that the vast majority of planets outside of our solar system exist inside a vast dusty disk of debris relatively close to the center of the solar system. But HD 106906b is far beyond its solar system’s disk — so far away that it takes 1,500 years for the planet to orbit its star. HD 106906b is currently at least 650 times as far from its star as the Earth is from our sun.

    “Our current planet formation theories do not account for a planet beyond its debris disk,” Naoz said.

    The study’s lead author is Erika Nesvold, a postdoctoral fellow at the Carnegie Institution for Science whom Naoz mentors. She wrote software called Superparticle-Method Algorithm for Collisions in Kuiper belts and debris disks, or SMACK, that allowed the researchers to create a model of the planet’s orbital path — a critical step because HD 106906b orbits so slowly that the researchers can barely see it move.

    The research, published online in the Astrophysical Journal Letters, suggests that the planet formed outside the disk, where it’s visible it today, as opposed to having been formed inside the debris disk and then having been thrust far beyond it.

    Naoz said that conclusion helps explain the shape of the debris disk. “It works perfectly,” she said.

    The planet’s orbit is elliptical; it gets much closer to the star on one side of its orbit than on the other side. And its gravity produces an elliptical shape in the disk as well. One side of the disk is closer to the star than the other side, and the dust on that side is warmer and glows brighter as a result.

    The debris disk was photographed in 2016 by American and European astronomers. According to Naoz, the disk is an analog to our solar system’s Kuiper belt — an enormous cluster of small bodies like comets and minor planets located beyond Neptune.

    The researchers don’t know if there are additional planets inside the disk, but using Nesvold’s software — which also been used to study other debris disks in the universe — they were able to re-create the shape of the disk without adding another planet into the model, as some astronomers had thought would be required.

    Debris disks are composed of gas, dust and ice, and they play a key role in the formation of planets. Typically, Naoz said, planets form after a gas cloud collapses due to its own gravity, forming a disk — where planets are created — and a star. As the gas slowly evaporates, the dust and debris rotate and collide around the young star until gravity pushes them away, forming a structure like our solar system’s Kuiper belt.

    “In our solar system, we’ve had billions of years of evolution,” said Michael Fitzgerald, UCLA associate professor of physics and astronomy, and the study’s other co-author. “We’re seeing this young system revealed to us before it has had a chance to dynamically mature.”

    Naoz said the researchers’ conclusions do not require any exotic physics or hidden planets to explain them, which is not always the case in studying other solar systems.

    “There are no assumptions; this is just physics,” she said.

    Naoz’s research was funded by a research fellowship from the Alfred P. Sloan Foundation. Nesvold’s was supported by a Carnegie Department of Terrestrial Magnetism postdoctoral fellowship.

    See the full article here .

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    UC LA Campus

    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 2:23 pm on March 15, 2017 Permalink | Reply
    Tags: , , , Carnegie Institution For Science, ,   

    From Astronomy: “There’s a supernova occurring right now in NGC 5643” 

    Astronomy magazine

    astronomy.com

    March 15, 2017
    Alison Klesman

    Meet “Bob,” the second Type Ia supernova in the galaxy since 2013

    1
    Racheal Beaton / Carnegie Institution for Science

    When most people hear the word supernova, they envision a massive star reaching the end of its life and exploding outwards to leave a ghostly remnant in its place. This is called a Type II supernova — the spectacular Supernova 1987A, which recently celebrated its 30th anniversary, was a Type II.

    2
    Supernova 1987A NASA

    Alternatively, a Type Ia supernova occurs when a white dwarf, the remnant of a Sun-like star, grows too massive after stripping a binary companion star of its outer layers. When the white dwarf reaches a critical mass, a runaway fusion reaction occurs in its core and the star explodes in a Type Ia supernova. Such a supernova has just been spotted occurring in a galaxy about 55 million light-years away.

    Announced by Rachael Beaton at the the Observatories of the Carnegie Institution for Science in Pasadena, CA, and known as 2017cbv (though Beaton has nicknamed it Bob), the explosion was spotted in NGC 5643, a spiral galaxy in the constellation Lupus. The area of the sky it inhabits is also part of the area covered by the Carnegie-Irvine Galaxy Survey, a project aimed at gathering optical and near-infrared images of bright Southern Hemisphere galaxies. NGC 5643 was also the home galaxy of SN 2013aa, which occurred in early 2013.

    Type Ia supernovae play an extremely important role as rungs on the astronomical distance ladder that allows astronomers to measure the distance to faraway galaxies. They’ve also played a critical role in measuring the accelerating expansion of the universe. Because they occur in white dwarfs of exactly the same mass every time (that critical mass mentioned earlier: about 1.4 times the mass of the Sun), Type Ia supernovae are always the same brightness, which means astronomers can use them as standard candles. Knowing how bright the explosion is in terms of absolute luminosity allows astronomers to then work backwards to calculate the distance to the object based on how bright it appears.

    But the word “exactly” is perhaps a bit misleading. Not every star system in which a Type Ia supernova occurs can be exactly the same. Moreover, events in the real world do not always reflect the precise nature of theoretical calculations — as in, some white dwarfs might explode at a mass slightly under 1.4 solar masses, while others might grow a little heavier than this limit before exploding. The fact that 2017cbv is the second recorded Type Ia supernova to occur in NGC 5643 is thus extremely valuable. By comparing the distance to the galaxy as calculated from each supernova, astronomers can better characterize the real-world variance in supernova Type Ia magnitudes that occur, which in turn will improve the accuracy of using these events to measure distance.

    See the full article here .

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  • richardmitnick 9:51 pm on March 2, 2017 Permalink | Reply
    Tags: , Carnegie Institution For Science, , Woods Hole Oceanographic Institution   

    From Carnegie: “Melting temperature of Earth’s mantle depends on water” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    A joint study between Carnegie and the Woods Hole Oceanographic Institution has determined that the average temperature of Earth’s mantle beneath ocean basins is about 110 degrees Fahrenheit (60 Celsius) higher than previously thought, due to water present in deep minerals. The results are published in Science.

    Earth’s mantle, the layer just beneath the crust, is the source of most of the magma that erupts at volcanoes. Minerals that make up the mantle contain small amounts of water, not as a liquid, but as individual molecules in the mineral’s atomic structure. Mid-ocean ridges, volcanic undersea mountain ranges, are formed when these mantle minerals exceed their melting point, become partially molten, and produce magma that ascends to the surface. As the magmas cool, they form basalt, the most-common rock on Earth and the basis of oceanic crust. In these oceanic ridges, basalt can be three to four miles thick.

    1
    An image of one of the team’s lab mimicry experiments, which was conducted in a capsule made of gold-palladium alloy. The black boxes highlight the locations of olivine grains, and the dark pits in the olivines are actual measurements for the water content of the olivine. The peridotite is the super fine-grained matrix. Image is courtesy of Emily Sarafian.

    Studying these undersea ranges can teach scientists about what is happening in the mantle, and about the Earth’s subsurface geochemistry.

    One longstanding question has been a measurement of what’s called the mantle’s potential temperature. Potential temperature is a quantification of the average temperature of a dynamic system if every part of it were theoretically brought to the same pressure. Determining the potential temperature of a mantle system allows scientists better to understand flow pathways and conductivity beneath the Earth’s crust. The potential temperature of an area of the mantle can be more closely estimated by knowing the melting point of the mantle rocks that eventually erupt as magma and then cool to form the oceanic crust.

    In damp conditions, the melting point of peridotite, which melts to form the bulk of mid-ocean ridge basalts, is dramatically lower than in dry conditions, regardless of pressure. This means that the depth at which the mantle rocks start to melt and well up to the surface will be different if the peridotite contains water, and beneath the oceanic crust, the upper mantle is thought to contain small amounts of water—between 50 and 200 parts per million in the minerals of mantle rock.

    So lead author Emily Sarafian of Woods Hole, Carnegie’s Erik Hauri, and their team set out to use lab experiments in order to determine the melting point of peridotite under mantle-like pressures in the presence of known amounts of water.

    “Small amounts of water have a big effect on melting temperature, and this is the first time experiments have ever been conducted to determine precisely how the mantle’s melting temperature depends on such small amounts of water,” Hauri said.

    They found that the potential temperature of the mantle beneath the oceanic crust is hotter than had previously been estimated.

    “These results may change our understanding of the mantle’s viscosity and how it influences some tectonic plate movements,” Sarafian added.

    The study’s other co-authors are Glenn Gaetani and Adam Sarafian, also of Woods Hole.

    See the full article here .

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 10:56 pm on March 1, 2017 Permalink | Reply
    Tags: , , , Carnegie Institution For Science, , Initial mass function, TW Hya   

    From Carnegie: “Hunting for giant planet analogs in our own backyard” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    March 01, 2017

    There may be a large number of undetected bright, substellar objects similar to giant exoplanets in our own solar neighborhood, according to new work from a team led by Carnegie’s Jonathan Gagné and including researchers from the Institute for Research on Exoplanets (iREx) at Université de Montréal. It is published by The Astrophysical Journal Supplement Series.

    1
    An artist’s conception of a free-floating planet analog courtesy of NASA/JPL.

    Recent studies of an association of stars called TW Hya have revealed some of the first known isolated giant planet-sized objects in the neighborhood of our own Sun, about 100 light years away.

    1
    TW Hydrae protoplanetary disk (NASA / ESA / J. Debes, STScI / H. Jang-Condell, University of Wyoming / A. Weinberger, Carnegie Institution of Washington / A. Roberge, Goddard Space Flight Center / G. Schneider, University of Arizona, Steward Observatory / A. Feild, STScI, AURA)

    This group contains a few dozen 10-million-year-old stars, all moving together through space.

    In order to determine whether or not there are more stand-alone planetary mass-sized objects like these in the TW Hya association, Gagné and his team undertook the calculation of an astronomical measurement called the initial mass function. This function can be used to determine the distribution of mass in the group and to predict the number of undiscovered objects that might exist inside of it.

    “The initial mass function of TW Hya had never been published before,” Gagné said.

    In the process of this analysis, the team was able to determine that there are probably many more objects between five and seven times the mass of Jupiter in the association that haven’t been discovered yet.

    “The TW Hya association extends out to a distance of ~250 light years, but our instruments aren’t sensitive enough yet to detect giant planets-like members at this distance, hence many of them might remain to be discovered,” Gagné added.

    This work was supported in part through grants from the Natural Science and Engineering Research Council of Canada, the U.S. National Science Foundation, and the NASA NExSS program.

    See the full article here .

    Please help promote STEM in your local schools.

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 5:40 pm on February 21, 2017 Permalink | Reply
    Tags: , , Carnegie Institution For Science, Gas giants   

    From Carnegie: “Prediction: More gas-giants will be found orbiting Sun-like stars” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    1
    Boss’ model of a planet-forming disk, which demonstrates that gas giant planets could be found orbiting Sun-like stars at distances similar to Jupiter and Saturn. The disk extends from 4 to 20 times the distance of the Earth from the Sun. You can see the spiral arms forming in the midplane of the disk. The disk instability theory suggests that gas giant planets can form from the clumps seen in the densest regions of the spiral arms.

    February 21, 2017
    No writer credit

    New planetary formation models from Carnegie’s Alan Boss indicate that there may be an undiscovered population of gas giant planets orbiting around Sun-like stars at distances similar to those of Jupiter and Saturn. His work is published by The Astrophysical Journal.

    The population of exoplanets discovered by ongoing planet-hunting projects continues to increase. These discoveries can improve models that predict where to look for more of them.

    The planets predicted by Boss in this study could hold the key to solving a longstanding debate about the formation of our Solar System’s giant planets out of the disk of gas and dust that surrounded the Sun in its youth.

    One theory holds that gas giants form just like terrestrial planets do—by the slow accretion of rocky material from the rotating disk—until the object contains enough material to gravitationally attract a very large envelope of gas around a solid core. The other theory states that gas giant planets form rapidly when the disk gas forms spiral arms, which increase in mass and density until distinct clumps form that coalesce into baby gas giant planets.

    One problem with the first option, called core accretion, is that it can’t explain how gas giant planets form beyond a certain orbital distance from their host stars—a phenomenon that is increasingly found by intrepid planet hunters. However, models of the second theory, called disk instability, have indicated the formation of planets with orbits between about 20 and 50 times the distance between the Earth and the Sun.

    “Given the existence of gas giant planets on such wide orbits, disk instability or something similar must be involved in the creation of at least some exoplanets,” Boss said. “However, whether or not this method could create closer-orbiting gas giant planets remains unanswered.”

    Boss set out to use his modeling tools to learn if gas giant planets can form closer to their host stars by taking a new look at the disk-cooling process. His simulations indicate that there may be a largely unseen population of gas giant planets orbiting Sun-like stars at distances between 6 and 16 times that separating the Earth and the Sun. (For context Jupiter is just over five times as distant from the Sun as Earth is, and Saturn is over nine times as distant.)

    “NASA’s upcoming Wide Field Infrared Survey Telescope [WFIRST]may be ideally suited to test my predictions here,” Boss added.

    NASA/WFIRST
    NASA/WFIRST

    See the full article here .

    Please help promote STEM in your local schools.

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    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 4:56 pm on February 20, 2017 Permalink | Reply
    Tags: , , Carnegie Institution For Science, Nickel is the key to unlocking the mystery, Why are there different “flavors” of iron around the Solar System?   

    From Carnegie: “Why are there different “flavors” of iron around the Solar System?” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    February 20, 2017
    Reference to Person:
    Anat Shahar

    New work from Carnegie’s Stephen Elardo and Anat Shahar shows that interactions between iron and nickel under the extreme pressures and temperatures similar to a planetary interior can help scientists understand the period in our Solar System’s youth when planets were forming and their cores were created. Their findings are published by Nature Geoscience.

    Earth and other rocky planets formed as the matter surrounding our young Sun slowly accreted. At some point in Earth’s earliest years, its core formed through a process called differentiation—when the denser materials, like iron, sunk inward toward the center. This formed the layered composition the planet has today, with an iron core and a silicate upper mantle and crust.

    Scientists can’t take samples of the planets’ cores. But they can study iron chemistry to help understand the differences between Earth’s differentiation event and how the process likely worked on other planets and asteroids.

    One key to researching Earth’s differentiation period is studying variations in iron isotopes in samples of ancient rocks and minerals from Earth, as well as from the Moon, and other planets or planetary bodies.

    Every element contains a unique and fixed number of protons, but the number of neutrons in an atom can vary. Each variation is a different isotope. As a result of this difference in neutrons, isotopes have slightly different masses. These slight differences mean that some isotopes are preferred by certain reactions, which results in an imbalance in the ratio of each isotope incorporated into the end products of these reactions.

    One outstanding mystery on this front has been the significant variation between iron isotope ratios found in samples of hardened lava that erupted from Earth’s upper mantle and samples from primitive meteorites, asteroids, the Moon, and Mars. Other researchers had suggested these variations were caused by the Moon-forming giant impact or by chemical variations in the solar nebula.

    Elardo and Shahar were able to use laboratory tools to mimic the conditions found deep inside the Earth and other planets in order to determine why iron isotopic ratios can vary under different planetary formation conditions.

    They found that nickel is the key to unlocking the mystery.

    Under the conditions in which the Moon, Mars, and the asteroid Vesta’s cores were formed, preferential interactions with nickel retain high concentrations of lighter iron isotopes in the mantle. However, under the hotter and higher-pressure conditions expected during Earth’s core formation process, this nickel effect disappears, which can help explain the differences between lavas from Earth and other planetary bodies, and the similarity between Earth’s mantle and primitive meteorites.

    “There’s still a lot to learn about the geochemical evolution of planets,” Elardo said. “But laboratory experiments allow us to probe to depths we can’t reach and understand how planetary interiors formed and changed through time.”

    1
    A scanning electron microscope image of one of the experiments in Elardo and Shahar’s paper that shows a bright, semi-spherical metal (representing a core) next to a gray, quenched silicate (representing a magma ocean). Image is courtesy of Stephen Elardo.

    This work was funded by a grant from the National Science Foundation.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
  • richardmitnick 11:34 am on October 21, 2016 Permalink | Reply
    Tags: , , Carnegie Institution For Science, DiskDetective.org, Found: Oldest known planet-forming disk   

    From Carnegie: “Found: Oldest known planet-forming disk” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    October 21, 2016

    1
    An artist’s conception of this unusual system, courtesy of Jonathan Holden/Disk Detective.

    A group of citizen scientists and professional astronomers, including Carnegie’s Jonathan Gagné, joined forces to discover an unusual hunting ground for exoplanets. They found a star surrounded by the oldest known circumstellar disk—a primordial ring of gas and dust that orbits around a young star and from which planets can form as the material collides and aggregates.

    Led by Steven Silverberg of University of Oklahoma, the team described a newly identified red dwarf star with a warm circumstellar disk, of the kind associated with young planetary systems. Circumstellar disks around red dwarfs like this one are rare to begin with, but this star, called AWI0005x3s, appears to have sustained its disk for an exceptionally long time. The findings are published by The Astrophysical Journal Letters.

    “Most disks of this kind fade away in less than 30 million years,” said Silverberg. “This particular red dwarf is a candidate member of the Carina stellar association, which would make it around 45 million years old [like the rest of the stars in that group]. It’s the oldest red dwarf system with a disk we’ve seen in one of these associations.”

    The discovery relied on citizen scientists from Disk Detective, a project led by NASA/GSFC’s Dr. Marc Kuchner that’s designed to find new circumstellar disks. At the project’s website, DiskDetective.org, users make classifications by viewing ten-second videos of data from NASA surveys, including the Wide-field Infrared Survey Explorer mission (WISE) and Two-Micron All Sky Survey (2MASS) projects.

    NASA/WISE Telescope
    NASA/WISE Telescope

    Caltech 2MASS Telescopes, a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center (IPAC) at Caltech, at the Whipple Observatory on Mt. Hopkins south of Tucson, AZ, and at the Cerro Tololo Inter-American Observatory near La Serena, Chile.
    Caltech 2MASS telescope interior
    2MASS Telescope

    Since the launch of the website in January 2014, roughly 30,000 citizen scientists have participated in this process, performing roughly 2 million classifications of celestial objects.

    “Without the help of the citizen scientists examining these objects and finding the good ones, we might never have spotted this object,” Kuchner said. “The WISE mission alone found 747 million [warm infrared] objects, of which we expect a few thousand to be circumstellar disks.”

    “Unraveling the mysteries of our universe, while contributing to the advancement of astronomy, is without a doubt a dream come true,” says Hugo Durantini Luca from Argentina, one of eight citizen scientist co-authors.

    Determining the age of a star can be tricky or impossible. But the Carina association, where this red dwarf was found, is a group of stars whose motions through the Galaxy indicate that they were all born at roughly the same time in the same stellar nursery.

    Carnegie’s Gagné devised a test that showed this newly found red dwarf and its disk are likely part of the Carina association, which was key to revealing its surprising age.

    “It is surprising to see a circumstellar disk around a star that may be 45 million years old, because we normally expect these disks to dissipate within a few million years,” Gagné explained. “More observations will be needed to determine whether the star is really as old as we suspect, and if it turns out to be, it will certainly become a benchmark system to understand the lifetime of disks.”

    Knowing that this star and its disk are so old may help scientists understand why M dwarf disks appear to be so rare.

    This star and its disk are interesting for another reason: the possibility that it could host extrasolar planets. Most of the extrasolar planets that have been found by telescopes have been located in disks similar to the one around this unusual red dwarf. Moreover, this particular star is the same spectral type as Proxima Centauri, the Sun’s nearest neighbor, which was shown to host at least one exoplanet, the famous Proxima b, in research published earlier this year.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile.
    6.5 meter Magellan Telescopes located at Carnegie’s Las Campanas Observatory, Chile

     
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