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  • richardmitnick 2:32 pm on June 21, 2019 Permalink | Reply
    Tags: "Tough Times for Binaries Near Black Holes", AAS NOVA, , , , ,   

    From AAS NOVA: “Tough Times for Binaries Near Black Holes” 

    AASNOVA

    From AAS NOVA

    21 June 2019
    Kerry Hensley

    1
    This Hubble image shows the Milky Way’s stellar downtown in the infrared. A new study explores how exposure to a nearby supermassive black hole affects binary systems. [NASA, ESA, and Hubble Heritage Team (STScI/AURA), Acknowledgment: T. Do, Andrea Ghez (UCLA), V. Bajaj (STScI)]

    What happens to binary stars under the influence of a nearby supermassive black hole? A new study shows that things can go one of two ways — being torn apart or becoming closer than ever.

    2
    An artist’s impression of an X-ray binary, many of which are seen in the galactic center. [ESA/NASA/Felix Mirabel]

    Life in Galactic Downtown

    There’s a lot going on in the galactic center. The crowded stellar environs near the Milky Way’s central black hole have long been studied in order to understand how the presence of a nearby black hole can shape stellar populations in our galaxy and others.

    A quick peek at the center of the Milky Way reveals that it plays host to an unusually large number of interesting astrophysical phenomena like stellar mergers, hyper-velocity stars, and X-ray sources that could point to cataclysmic variables or binary systems with a neutron-star or stellar-mass-black-hole component.

    How do these various unusual objects form in the galactic center? One possibility is that ordinary, garden-variety binary stars do strange things when they evolve in the extreme environment near a supermassive black hole.

    4
    A histogram of the binary mergers as a function of time in the simulation. [Stephan et al. 2019]

    Binary Systems Through the Ages

    To explore this scenario, a team of astronomers led by Alexander Stephan (University of California, Los Angeles) simulated the evolution of main-sequence binaries near a supermassive black hole. Specifically, they used Monte Carlo simulations of binary systems in the inner 0.33 light-years of a Milky-Way-like galaxy with a four-million-solar-mass black hole at its center.

    Stephan and coauthors considered how the dynamics of binary systems with a range of starting masses would change over time as close encounters with other stars, gentle nudges from more distant objects, and the looming gravitational influence of the black hole warp and disturb their orbits.

    While the orbits of the binary systems change over time due to gravitational interactions, the individual stars are busy evolving as well — a process that the authors captured by using a single-star stellar evolution code. Post-main-sequence evolution is important for the dynamics of a binary system since it can lead to mass transfer between the stars or even stellar mergers.


    A flowchart of the simulated outcomes of binary evolution. [Stephan et al. 2019]

    So Long, Partner

    If you belong to a binary system and you’re hoping to spend the rest of your days with your companion, the news isn’t good: the authors found that after a few hundred million years, 75% of binary systems have been torn apart by gravitational interactions.

    Of the remaining 25%, about half end up merging due to dynamical perturbations or because one star has swelled into a red giant and engulfed the other. The other half have even more exotic outcomes, becoming close binary systems containing white dwarfs, neutron stars, or black holes.

    Clearly, the presence of a nearby supermassive black hole shakes up the evolution of otherwise ordinary binary stars: these rare systems are the precursors to Type Ia supernovae, cataclysmic variables, and compact object mergers that can generate gravitational waves.

    Citation

    “The Fate of Binaries in the Galactic Center: The Mundane and the Exotic,” Alexander Stephan et al 2019 ApJ 878 58.
    https://iopscience.iop.org/article/10.3847/1538-4357/ab1e4d

    See the full article here .

    An absolutley wonderful video, “Inside The Milky Way” from NatGeo, is available om Youtube
    Features James Bullock, UC Irvine, and Robert Kirshner, Havard


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 11:28 am on June 20, 2019 Permalink | Reply
    Tags: "Two Planets Straddling the Gap", AAS NOVA, , , , ,   

    From AAS NOVA: “Two Planets Straddling the Gap” 

    AASNOVA

    From AAS NOVA

    19 June 2019
    Susanna Kohler

    1
    We’ve observed a diverse range of planets larger than Earth (a few are shown in these illustrations), but they tend to fall into two size categories: super-Earth or mini-Neptune. [NASA Ames/JPL-Caltech]

    As of last week, the count of confirmed exoplanets officially exceeds 4,000 — and while we’ve learned a lot about planet formation from this wealth of data, it’s also prompted new questions. Could the recent detection of two intriguing new planets shed light on one of these open puzzles?

    2
    In 2017, a team of scientists led by B.J. Fulton identified a gap in the distribution of radii of small Kepler-discovered planets. [NASA/Ames/Caltech/University of Hawaii (B. J. Fulton]

    Mind the Gap

    Our growing exoplanet statistics recently revealed a curious trait: there’s a gap in the radius distribution of planets slightly larger than Earth. Rocky super-Earth planets of up to ~1.5 Earth radii are relatively common, as are gaseous mini-Neptunes in the range of ~2–4 Earth radii. But we’ve detected very few planets in between these sizes.

    What’s the cause of this odd deficit? One theory is that high-energy radiation emitted by stars early in their lifetimes erodes the atmospheres of planets that are too close in, stripping them of their expansive shells of gas and leaving behind only their dense, rocky cores. Planets that lie further out or start with a thicker shell may be spared this fate, retaining some of their gas for a significantly larger, fluffier construction.

    3
    Folded light curves for HD 15337 showing the transits of planets b (top) and c (bottom). [Gandolfi et al. 2019]

    Disentangling Factors

    This theory can be difficult to test, however, due to the large number of intertwined variables. The super-Earths and mini-Neptunes we’ve observed lie at varying distances from their host stars — but they also orbit around different types of stars with very different radiation histories. It’s hard to tell what role these various factors play in the planets’ evolution.

    But a recent discovery from the Transiting Exoplanet Survey Satellite (TESS) may help simplify this picture. With more than 750 planet-candidate detections so far, TESS is rapidly adding to our exoplanet statistics — and two TESS-discovered planets around HD 15337 may be especially useful for better understanding the radius gap.

    NASA/MIT TESS replaced Kepler in search for exoplanets

    A Non-Identical Pair

    In a publication led by Davide Gandolfi (University of Turin, Italy), a team of scientists carefully analyzes the TESS light curves for HD 15337, as well as archival spectroscopic data from the High Accuracy Radial velocity Planet Searcher. They show that there is evidence for the presence of two planets — HD 15337 b and c — that have similar masses: ~7.5 and ~8.1 Earth masses, respectively.

    But while HD 15337 b appears to be a close-in (period of 4.8 days), rocky super-Earth with radius of 1.6 Earth radii and density of 9.3 g/cm3, HD 15337 c lies further out (period of 17.2 days) and is a fluffy mini-Neptune, with a radius of 2.4 Earth radii and a density of 3.2 g/cm3.

    Since these two planets orbit the same star, it seems likely that their different orbital radii are what led to their places on either side of the radius gap. Using a planet atmospheric evolution algorithm, Gandolfi and collaborators show that the properties of the two planets can be produced by high-energy radiation from HD 15337 early in the system’s lifetime.

    As our observational statistics for exoplanets continue to grow, it’s exciting to see how these continued discoveries can both raise and address new questions of planet formation and evolution. Who knows what else we’ll learn as detections continue to pile up!

    Citation

    “The Transiting Multi-planet System HD15337: Two Nearly Equal-mass Planets Straddling the Radius Gap,” Davide Gandolfi et al 2019 ApJL 876 L24.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab17d9

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 9:11 am on June 2, 2019 Permalink | Reply
    Tags: "Building a Pair of Blue Stragglers", AAS NOVA, , , ,   

    From AAS NOVA: “Building a Pair of Blue Stragglers” 

    AASNOVA

    From AAS NOVA

    31 May 2019
    Susanna Kohler

    1
    This star cluster, NGC 6397, is one of many clusters that play host to a number of bright blue stragglers. A new study explores one way in which blue stragglers may form. [ESA/Hubble]

    Unusually blue and bright stars may not have only themselves to thank for their uniqueness. A new study looks at one way these unconventional objects might form in clusters … with a little help from a friend.

    Cluster Stand-Outs

    A stellar cluster is a group of stars that were all born together and should evolve in a consistent way. According to stellar evolution theory, for a given cluster, the stars of the cluster should fall onto a well-defined track on a Herzsprung–Russell (H–R) diagram — a plot of stellar brightness vs. color — with the stars’ location on the track dependent only on their initial mass.

    But a few stars defy this logic. These so-called “blue stragglers” seem to have been left behind as their fellow cluster inhabitants evolved without them; on the H–R diagram, blue stragglers lie alone above the main-sequence turnoff point, shining brighter and bluer than they should be.

    Just a Little Boost?

    What causes these unorthodox stars? The simplest explanation is that they are main-sequence stars that belatedly received a bump in their mass. Theorists favor two possible formation channels:

    Mass transfer from an evolved donor onto a main-sequence star in a binary, which increases the main-sequence star’s mass and consequently causes it to become brighter and hotter.
    Collision and merger of two main-sequence stars, which forms a new, more massive main-sequence star that is brighter and hotter than usual.

    But these two channels can only explain some observed blue stragglers; other systems — like WOCS ID 7782, a binary consisting of two blue stragglers in a 10-day orbit — are unlikely to have formed in either of these ways.

    With WOCS ID 7782 in mind, scientists Simon Portegies Zwart (Leiden University) and Nathan Leigh (American Museum of Natural History; Stony Brook University; and University of Concepción, Chile) have now proposed an alternative formation channel.

    A Third Star in the Mix

    Portegies Zwart and Leigh’s model relies on one important element: a third star. In their proposed scenario, two main-sequence stars in a close binary are orbited by a giant, evolved companion star. As this evolved star ages and overflows its Roche lobe, gas flows from it onto the main-sequence binary, increasing the masses of the two inner stars.

    2
    Snapshot from one of the authors’ simulated triple systems. The binary system at left is being fed by gas from the outer tertiary companion on the right. [Portegies Zwart & Leigh 2019]

    The authors use simulations to show that the final result of this process can be a close binary with two similar-mass blue stragglers, just as seen in WOCS ID 7782. In this scenario, the outer companion eventually evolves into a hard-to-spot white dwarf on a wide orbit with a period of more than ~5.8 years.

    In addition to potentially explaining WOCS ID 7782, Portegies Zwart and Leigh’s model can produce a number of other masses, geometries, and configurations for blue-straggler systems, depending on the initial masses and separations of the binary and the outer companion. This formation scenario — which relies on just a little help from a friend — may therefore go a long way toward explaining the formation of the blue-straggler systems that have stumped us before now.

    Citation

    “A Triple Origin for Twin Blue Stragglers in Close Binaries,” Simon Portegies Zwart and Nathan W. C. Leigh 2019 ApJL 876 L33.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab1b75/meta

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 11:34 am on May 30, 2019 Permalink | Reply
    Tags: "Do Active Galactic Nuclei Help or Hurt Life?", AAS NOVA, , , ,   

    From AAS NOVA: “Do Active Galactic Nuclei Help or Hurt Life?” 

    AASNOVA

    From AAS NOVA

    29 May 2019
    Susanna Kohler

    1
    Artist’s illustration of an active galactic nucleus shrouded by gas and dust. Do such sources help or hurt the formation and survival of life in a galaxy? [NASA/JPL-Caltech]

    How does life arise on exoplanets? What environments are necessary for it to survive? What conditions pose threats to life? These are some of the many questions of astrobiology, the study of life beyond our solar system.

    While much research explores how stellar radiation influences whether planets can form or sustain life, fewer studies examine other sources of radiation. Today’s study explores extreme sources: the violent and bright centers of active galaxies.

    Extreme Sources

    Active galactic nuclei, or AGN, contain enormous supermassive black holes that rapidly accrete gas and dust, emitting harsh high-energy radiation in the process. Could this radiation seriously hamper the formation and evolution of extraterrestrial life on nearby planets?

    A recent study led by Manasvi Lingam (Harvard University) suggests the opposite may be true: the radiation from AGN has the potential to aid (Earth-like) life’s chances of formation and survival.

    The Cons

    Let’s start with the downside of having an enormous source of high-energy radiation lurking nearby: as we’ve all experienced via the occasional sunburn, too much ultraviolet (UV) radiation can have harmful effects for life. On the extreme end, an excess of UV radiation can inhibit photosynthesis — a process on which the vast majority of Earth-based life relies for survival — and can damage DNA and other biomolecules.

    But how much is too much? Lingam and collaborators conduct a series of calculations to show that an AGN doesn’t have much of an impact on the vast majority of planets in a galaxy. If the Milky Way had an active nucleus, the danger zone for potential extinction via UV radiation would extend to just ~100 light-years from the AGN — a tiny distance on the scale of our 100,000-light-year galaxy.

    3
    Artist’s impression of radiation as a driver of the chemistry of early life. [NASA]

    The Pros

    But UV light isn’t all bad! In fact, UV radiation is a necessary ingredient for the prebiotic chemical reactions that led to the synthesis of biomolecular building blocks on Earth. Lingam and collaborators show that, within a certain distance of the AGN (out to ~150 light-years in our Milky-Way-size active-galaxy example), UV radiation from the accreting black hole could actually jump-start these chemical reactions and eventually lead to the formation of life.

    What’s more, the authors demonstrate that the visible light from AGN can power photosynthesis on nearby planets — which could be particularly useful for free-floating planets that don’t have a host star to provide that light. The zone for which this holds true is broad: out to more than 1,100 light-years, for a Milky-Way-size active galaxy.

    4
    Author estimates for the distances at which an AGN could enable prebiotic chemistry (dO, blue line), facilitate potential extinction events (dB, red line), and permit photosynthesis (dP, green line) as a function of the black hole mass. Solid and dashed lines indicate two different levels of AGN power. [Lingam et al. 2019]

    The Upshot

    Ultimately, Lingam and collaborators find that AGN won’t influence life formation and survival either way for the vast majority of planets in a Milky-Way-size galaxy; beyond ~3,000 light-years from the galactic center, planets won’t notice the radiation from the AGN.

    But in other types of galaxies — like those with especially large supermassive black holes, or compact dwarf galaxies with high stellar densities at their center — AGN could play a significant role in sparking life and helping it to stay alive.

    Citation

    “Active Galactic Nuclei: Boon or Bane for Biota?,” Manasvi Lingam et al 2019 ApJ 877 62.
    https://iopscience.iop.org/article/10.3847/1538-4357/ab1b2f

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 12:03 pm on May 24, 2019 Permalink | Reply
    Tags: "Plasma Processes in Mars’s Shadow", AAS NOVA, , , , ,   

    From AAS NOVA: “Plasma Processes in Mars’s Shadow” 

    AASNOVA

    From AAS NOVA

    24 May 2019
    Kerry Hensley

    1
    NASA’s MAVEN spacecraft has been in orbit around Mars since 2014. The goal of the MAVEN mission is to understand how Mars’s atmosphere has evolved over the course of solar system history. [NASA/Goddard]

    NASA Mars MAVEN

    When solar ultraviolet and X-ray photons collide with atoms and molecules in Mars’s atmosphere, they form a layer of plasma called an ionosphere. That’s what happens on the sunlit side, at least. What’s going on in Mars’s shadow?

    2
    A cartoon depicting the interaction of the solar wind with Mars’s atmosphere, as well as likely regions for atmospheric escape. [NASA/GSFC]

    Planetary Plasma

    Even though there are no solar photons striking Mars’s atmosphere at night, plasma is still present — but it’s not immediately clear where it comes from. Does it come from bombardment by galactic cosmic rays or trapped solar-wind particles, or is it transported from the sunlit side by winds?

    And once the plasma has been produced, what happens to it? Is it lost when electrons and ions reunite to form neutrals, or does it escape the planet’s atmosphere entirely?

    One way to assess the sources and sinks of plasma is by calculating the rates of production by electron-impact ionization — when energetic electrons ionize neutrals through collisions — and loss by dissociative recombination — when molecular ions capture an electron and are split apart. If the rates are equal, those two processes dominate. If not, other processes must play a role.

    3
    From left to right, the densities of the major ion and neutral species, neutral (black) and electron (red) temperatures, and the average electron intensity. [Adapted from Cui et al. 2019]

    MAVEN on a Mission

    Evaluating whether or not the two rates are equal requires neutral and ion densities, electron temperatures, and a spectrum of incident energetic electrons. Luckily, NASA’s Mars Atmosphere and Volatile Evolution (MAVEN) spacecraft, which has been orbiting Mars since 2014, collects all that information and more.

    Normally, MAVEN comes within 150 km of Mars’s surface, but it occasionally drops its closest approach to 125 km. These so-called Deep Dip campaigns, of which there have been nine, give scientists a close look at the densest plasma in the ionosphere. In this study, a team led by Jun Cui (Sun Yat-sen University, Chinese Academy of Sciences, and National Astronomical Observatories, China) analyzed data from two Deep Dip orbits in 2015 and 2016.

    Using the in-situ measurements made along each orbit, Cui and collaborators calculated the rate at which CO2 — the dominant neutral species — is ionized by electron impacts and the rate at which O2+, NO+, and HCO+ — the three dominant ion species — dissociatively recombine.

    4
    Comparison of the dissociative recombination and electron-impact ionization rates for the two orbits. Open circles represent calculations made with individual measurements, while closed squares indicate average values for each altitude bin. The starred points have been corrected for instrumental effects. [Cui et al. 2019]

    A Complex Nightside Picture

    At low altitudes (below 140 km for the midnight orbit and 180 km for the dawn orbit), the authors found that the electron-impact ionization rate agrees with the dissociative recombination rate, which indicates that sources of plasma other than electron-impact ionization don’t play a major role at these altitudes.

    At high altitudes, however, the rate of electron-impact ionization is higher than the rate of dissociative recombination, which is a sign that there is another important plasma loss process happening at those altitudes. It’s possible that magnetic pressure gradients at those altitudes encourage ions to escape down Mars’s magnetotail.

    Last month, MAVEN finished its two-month aerobraking campaign, during which the spacecraft altitude dipped as low as ~125 km to use atmospheric drag to change its orbit, giving scientists a long look at Mars’s ionosphere. Expect more atmospheric news from MAVEN in the future!

    Citation

    “Evaluating Local Ionization Balance in the Nightside Martian Upper Atmosphere during MAVEN Deep Dip Campaigns,” J. Cui et al 2019 ApJL 876 L12.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab1b34/meta

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 8:48 am on May 21, 2019 Permalink | Reply
    Tags: "Featured Image: A Runaway Pulsar", AAS NOVA, , , ,   

    From AAS NOVA: “Featured Image: A Runaway Pulsar” 

    AASNOVA

    From AAS NOVA

    20 May 2019
    Susanna Kohler

    1

    In the dramatic false-color radio images above, captured by the Canadian Galactic Plane Survey (background) and the Very Large Array (zoomed-in inset), a pulsar — a rapidly spinning, magnetized neutron star — is seen plunging out of a supernova remnant and taking off into interstellar space. The green cross marks the center of the supernova remnant CTB 1, and the green circle marks the location of the pulsar PSR J0002+6216. The tail of radio-emitting gas extending behind the pulsar toward the nebula is a dead giveaway to this object’s origin: the pulsar was likely born from the very same supernova explosion that produced the remnant. Supernova explosions don’t have perfect symmetry, and the pulsar likely received a natal kick that sent it tearing away from its birthplace at tremendous speeds, causing it to eventually overtake the expanding shell of gas and dust. In a recent study led by Frank Schinzel (National Radio Astronomy Observatory), a team of scientists presents and discusses the evidence that this runaway pulsar came from CTB 1. To read more, check out the article below.
    Citation

    “The Tail of PSR J0002+6216 and the Supernova Remnant CTB 1,” F. K. Schinzel et al 2019 ApJL 876 L17.
    https://iopscience.iop.org/article/10.3847/2041-8213/ab18f7/meta

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 12:14 pm on May 17, 2019 Permalink | Reply
    Tags: AAS NOVA, , , , ,   

    From AAS NOVA: “Focus on SOFIA: HAWC+” 

    AASNOVA

    From AAS NOVA

    17 May 2019
    Susanna Kohler

    1
    This composite, false-color image shows the starburst galaxy Messier 82 as seen by Kitt Peak Observatory, the Spitzer Space Telescope, and SOFIA. The magnetic field detected by SOFIA, shown as streamlines, appears to be dragged along by the winds flowing from the poles of this galaxy. [NASA/SOFIA/E. Lopez-Rodriguez/Spitzer/J. Moustakas et al.]

    Kitt Peak National Observatory of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono O’odham Nation, 88 kilometers 55 mi west-southwest of Tucson, Arizona, Altitude 2,096 m (6,877 ft)

    NASA/Spitzer Infrared Telescope

    In December, AAS Nova Editor Susanna Kohler had the opportunity to fly aboard the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). This week we’re taking a look at that flight, as well as some of the recent science the observatory produced and published in an ApJ Letters Focus Issue.

    3
    The HAWC+ instrument mounted on the SOFIA telescope. [NASA]

    Meet HAWC+

    HAWC+ is a one-of-a-kind instrument: it’s the only currently operating astronomical camera that takes images in far-infrared light. HAWC+ observes in the 50-μm to 240-μm range at high angular resolution, affording us a detailed look at low-temperature phenomena, like the early stages of star and planet formation.

    In addition to the camera, HAWC+ also includes a polarimeter, which allows the instrument to measure the alignment of incoming light waves produced by dust emission. By observing this far-infrared polarization, HAWC+ can produce detailed maps of otherwise invisible celestial magnetic fields. The insight gained with HAWC+ spans an incredible range of astronomical sources, from nearby star-forming regions to the large-scale environments surrounding other galaxies.

    4
    Artist’s conception of Cygnus A, surrounded by the torus of dust and debris with jets launching from its center. Magnetic fields are illustrated trapping dust near the supermassive black hole at the galaxy’s core. [NASA/SOFIA/Lynette Cook]

    Some Recent HAWC+ Science

    Cygnus A is the closest and most powerful radio-loud active galactic nucleus. At its heart, a supermassive black hole is actively accreting material, producing enormous jets — but this core is difficult to learn about, because it is heavily shrouded by dust.

    In a recent study led by Enrique Lopez-Rodriguez (SOFIA Science Center; National Astronomical Observatory of Japan), a team of scientists has used HAWC+ to observe the polarized infrared emission from aligned dust grains in the dusty torus surrounding Cygnus A’s core. Lopez-Rodriguez and collaborators find that a coherent dusty and magnetic field structure dominates the infrared emission around the nucleus, suggesting that magnetic fields confine the torus and funnel the dust in to accrete onto the supermassive black hole.

    Messier 82 and NGC 253 are two nearby starburst galaxies — galaxies with a high rate of star formation. Such galaxies often have strong outflowing galactic winds, which are thought to contribute to the enrichment of the intergalactic medium with both heavy elements and magnetic fields.

    A study led by Terry Jay Jones (University of Minnesota) uses HAWC+ to map out the magnetic field geometry in the disk and central regions of these two galaxies. M82 shows the most spectacular results, revealing clear evidence for a massive polar outflow that drags the magnetic field vertically away from the disk along with entrained gas and dust.

    4
    SOFIA/HAWC+ 89 μm detection of the gravitationally lensed starburst galaxy J1429-0028. Right: false-color composite image of J1429-0028 from Hubble and Keck. [Ma et al. 2018]

    A study led by Jingzhe Ma (University of California, Irvine) presents the HAWC+ detection of the distant, gravitationally lensed starburst galaxy HATLAS J1429-0028. This beautiful system consists of an edge-on foreground disk galaxy and a nearly complete Einstein ring of an ultraluminous infrared background galaxy. What causes this background galaxy to shine so brightly in infrared wavelengths? The HAWC+ observations suggest it’s not due to emission from an active galactic nucleus; instead, this galaxy is likely powered purely by star formation.

    5
    The G 9 region, as represented by the Digital Palomar Observatory Sky Survey. The cyan polygon represents the SOFIA HAWC+ coverage of the filamentary dark cloud GF 9. The yellow diamond marks the YSO GF 9-2. [Clemens et al. 2018]

    In a recent study examining the geometry of magnetic fields surrounding sites of massive star formation, Dan Clemens (Boston University) and collaborators obtained HAWC+ observations of a young stellar object (YSO) embedded in a molecular cloud. The polarimetric measurements of HAWC+ revealed the magnetic field configuration around the YSO, the dense core that hosts it, and the clumpy filamentary dark cloud that surrounds it, GF 9.

    Surprisingly, the observations show a remarkably uniform magnetic field threading the entire region, from the outer, diffuse cloud edge all the way down to the smallest scales of the YSO surroundings. These results contradict some models of how cores and YSOs form, providing important information that will help us better understand this process.

    Citation

    ApJL Focus issue:
    Focus on New Results from SOFIA

    HAWC+ articles:
    “The Highly Polarized Dusty Emission Core of Cygnus A,” Enrique Lopez-Rodriguez et al. 2018 ApJL 861 L23. doi:10.3847/2041-8213/aacff5
    “SOFIA Far-infrared Imaging Polarimetry of M82 and NGC 253: Exploring the Supergalactic Wind,” Terry Jay Jones et al. 2019 ApJL 870 L9. doi:10.3847/2041-8213/aaf8b9
    “SOFIA/HAWC+ Detection of a Gravitationally Lensed Starburst Galaxy at z = 1.03,” Jingzhe Ma et al. 2018 ApJ 864 60. doi:10.3847/1538-4357/aad4a0
    “Magnetic Field Uniformity Across the GF 9-2 YSO, L1082C Dense Core, and GF 9 Filamentary Dark Cloud,” Dan P. Clemens et al. 2018 ApJ 867 79. doi:10.3847/1538-4357/aae2af

    Related Journal Articles

    Polarized Mid-infrared Synchrotron Emission in the Core of Cygnus A doi: 10.1088/0004-637X/793/2/81
    The Emission and Distribution of Dust of the Torus of NGC 1068 doi: 10.3847/1538-4357/aabd7b
    Subaru Spectroscopy and Spectral Modeling of Cygnus A doi: 10.1088/0004-637X/788/1/6
    SOFIA/HAWC+ Detection of a Gravitationally Lensed Starburst Galaxy at z = 1.03 doi: 10.3847/1538-4357/aad4a0
    The Spitzer View of FR I Radio Galaxies: On the Origin of the Nuclear Mid-Infrared Continuum doi: 10.1088/0004-637X/701/2/891
    Mid-infrared Spectroscopy of High-redshift 3CRR Sources doi: 10.1088/0004-637X/717/2/766

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 12:40 pm on May 16, 2019 Permalink | Reply
    Tags: "Focus on SOFIA: EXES", AAS NOVA, , , , ,   

    From AAS NOVA: “Focus on SOFIA: EXES” 

    AASNOVA

    From AAS NOVA

    6 May 2019
    Susanna Kohler

    1
    This false-color infrared image, captured by NASA’s WISE telescope, reveals young, massive stars (pink objects near center) forming in the Rho Ophiuchi cloud complex. SOFIA’s EXES spectrograph is well suited for studying the chemistry of massive star formation. [NASA/JPL-Caltech/WISE Team]

    In December, AAS Nova Editor Susanna Kohler had the opportunity to fly aboard the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). This week we’re taking a look at that flight, as well as some of the recent science the observatory produced and published in an ApJ Letters Focus Issue.

    One of SOFIA’s great strengths is that the instruments mounted on this flying telescope can be easily swapped out, allowing for a broad range of infrared observations. Three of SOFIA’s instruments are featured in science recently published in the ApJ Letters Focus Issue: the Far Infrared Field-Imaging Line Spectrometer (FIFI-LS), the High-Resolution Airborne Wideband Camera Plus (HAWC+), and the Echelon-Cross-Echelle Spectrograph (EXES).

    2
    The EXES instrument mounted on the SOFIA telescope. [NASA/SOFIA/EXES/Matthew Richter]

    Meet EXES

    EXES is used for high-resolution spectroscopy at mid-infrared wavelengths — from 4.5 to 28.3 µm — to study molecular gas in dense, quiescent clouds and protostellar disks. EXES uses a special coarsely-ruled aluminum reflection grating to spread light into a spectrum, allowing scientists to identify specific spectral lines associated with emission from different molecules.

    The instrument’s high spectral resolution enables the study of molecular hydrogen, water vapor, and methane from sources like molecular clouds, protoplanetary disks, interstellar shocks, circumstellar shells, and planetary atmospheres. For many sources, EXES is able to achieve comparable sensitivity even to space-based observatories like Spitzer.

    NASA/Spitzer Infrared Telescope

    3
    Image from the Subaru telescope showing the location of the Becklin-Neugebauer object in Orion. [NAOJ/Subaru Telescope]


    NAOJ/Subaru Telescope at Mauna Kea Hawaii, USA,4,207 m (13,802 ft) above sea level

    Some Recent EXES Science

    A young, massive star dubbed the Becklin-Neugebauer object is irrationally speeding through the Orion nebular cluster at a relative speed of ~30 km/s! One proposed explanation for this object’s unusual velocity is that it was caught in a three-body dynamical interaction inside a nebula, during which it was violently ejected.

    If true, we could expect that the Becklin-Neugebauer object might have dragged some of the hot, dense molecular gas along with it when it was ejected. A team of scientists led by Nick Indriolo (Space Telescope Science Institute) used EXES to search for signs of hot water molecules moving along with the Becklin-Neugebauer object, and came up empty-handed — adding one more perplexing clue to the mystery of this strange source.

    Hot molecular cores are compact regions of dense gas that represent an intermediary stage of massive star formation; once a protostar forms in a collapsing cloud, it heats its surroundings and drives an outflow of evaporating material.

    A study led by Andrew Barr (Leiden University, the Netherlands) explores the composition of the hot molecular core AFGL 2591 using EXES infrared observations. The authors detect carbon monosulfide (CS), a molecule that can be used to probe the physical conditions deep in the innermost parts of the hot core near the base of the outflow.

    4
    Hubble image of a nearby Young Stellar Object, V1331Cyg. [ESA/NASA/Hubble/K. Stapelfeldt/B. Stecklum/A. Choudhary]

    In another look at sulfur chemistry in massive star formation, Ryan Dungee (Institute for Astronomy, University of Hawaii) and collaborators observed warm sulfur dioxide gas (SO2) near the massive young stellar object (YSO) MonR2 IRS3, a collapsing protostar still embedded in a molecular cloud. The high resolution of EXES’s observations allowed the authors to identify the most likely source of the gas: sublimating ices in the hot core close to the massive young stellar object. These observations help us to understand the underlying chemistry of the birth of massive stars.

    5
    Composite image of Europa from Galileo and Voyager, superimposed on Hubble data that suggests the presence of plumes of water vapor at roughly the 7 o’clock position off Europa’s limb. [NASA/ESA/W. Sparks (STScI)/USGS Astrogeology Science Center]

    NASA/Galileo 1989-2003

    NASA/Voyager 1

    Does Jupiter’s moon Europa host plumes of water erupting from its surface? So suggest Hubble images from 2012 and recently re-analyzed data from NASA’s Galileo spacecraft. To test this theory, a team led by William Sparks (SETI Institute and Space Telescope Science Institute) used SOFIA/EXES to search for direct evidence of the presence of water vapor erupting from Europa’s surface.

    The result? If plumes are indeed present on Europa, they can’t be carrying much water vapor. EXES saw no evidence of plumes, placing an upper limit on the amount of water ejected from the moon in this way during SOFIA’s observations. This limit is lower than the amount of water implied by the previous Hubble observations — leaving yet another mystery unsolved and deepening the question of whether Europa has what it takes to support life.

    Citation

    ApJL Focus issue:
    Focus on New Results from SOFIA

    EXES articles:
    “High Spectral Resolution Observations toward Orion BN at 6 μm: No Evidence for Hot Water,” Nick Indriolo et al. 2018 ApJL 865 L18. doi:10.3847/2041-8213/aae1ff
    “Infrared Detection of Abundant CS in the Hot Core AFGL 2591 at High Spectral Resolution with SOFIA/EXES ,” Andrew G. Barr et al. 2018 ApJL 868 L2. doi:10.3847/2041-8213/aaeb23
    “High-resolution SOFIA/EXES Spectroscopy of SO2 Gas in the Massive Young Stellar Object MonR2 IRS3: Implications for the Sulfur Budget,” Ryan Dungee et al. 2018 ApJL 868 L10. doi:10.3847/2041-8213/aaeda9
    “A Search for Water Vapor Plumes on Europa using SOFIA,” W. B. Sparks et al. 2019 ApJL 871 L5. doi:10.3847/2041-8213/aafb0a

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 1:28 pm on May 15, 2019 Permalink | Reply
    Tags: "Focus on SOFIA: FIFI-LS", AAS NOVA, , , ,   

    From AAS NOVA: “Focus on SOFIA: FIFI-LS” 

    AASNOVA

    From AAS NOVA

    15 May 2019
    Susanna Kohler

    1
    This composite X-ray, optical, radio, and infrared image captures the active galaxy NGC 4258. SOFIA/FIFI-LS observations of the core of this galaxy reveal a molecular tracer associated with the energetic outflows from the galactic nucleus. [X-ray: NASA/CXC/Caltech/P.Ogle et al; Optical: NASA/STScI & R.Gendler; IR: NASA/JPL-Caltech; Radio: NSF/NRAO/VLA]

    NASA/ESA Hubble Telescope

    NASA/Chandra X-ray Telescope

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    In December, AAS Nova Editor Susanna Kohler had the opportunity to fly aboard the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA). This week we’re taking a look at that flight, as well as some of the recent science the observatory produced and published in an ApJ Letters Focus Issue.

    One of SOFIA’s great strengths is that the instruments mounted on this flying telescope can be easily swapped out, allowing for a broad range of infrared observations. Three of SOFIA’s instruments are featured in science recently published in the ApJ Letters Focus Issue: the Far Infrared Field-Imaging Line Spectrometer (FIFI-LS), the High-Resolution Airborne Wideband Camera Plus (HAWC+), and the Echelon-Cross-Echelle Spectrograph (EXES).

    2
    The FIFI-LS instrument mounted on the SOFIA telescope. [NASA/SOFIA/USRA/Greg Perryman]

    By simultaneously capturing both images and spectra, FIFI-LS is able to deeply probe the composition and physical properties (like pressure and temperature) of heavily dust-obscured, star-forming regions in our own galaxy, as well as those in nearby external galaxies and galactic nuclei.

    Some Recent FIFI-LS Science

    In a study led by Gerold Busch (University of Cologne, Germany), scientists detail the first detection with FIFI-LS of a nearby luminous AGN, or active galactic nucleus. Despite its relative nearness, this galaxy is still roughly 500 million light-years away, making it the most distant object ever studied with SOFIA.
    The team compares FIFI-LS’s spatially resolved observations of the infrared emission line [CII] in the galaxy to optical observations of Hα, an emission line known to trace star formation. By demonstrating that the two different types of emission occur in the same places in the galaxy, the team shows that [CII] emission can be used as a powerful diagnostic tool for tracing star formation even in distant galaxies — and even when those galaxies host luminous active nuclei.

    3
    Left: FIFI-LS image of [CII] emission from M51. Right: X-ray, optical, and infrared composite image of M51. The deficit of [CII] emission from the upper companion galaxy suggests it has a much lower star formation rate. [Left: Adapted from Pineda et al. 2018; Right: X-ray: NASA/CXC/SAO; Optical: Detlef Hartmann; Infrared: NASA/JPL-Caltech]

    A publication led by Jorge Pineda (Jet Propulsion Laboratory) details a SOFIA-produced map of [CII] emission in the spectacular grand design galaxy M51 and the small companion galaxy M51b with which it is merging. The map reveals a deficit of [CII] emission in the companion galaxy, suggesting this small galaxy isn’t forming stars at the same rate as its larger cousin.

    The molecular cloud BYF 73 is currently collapsing in on itself, making it a promising target in which to watch the formation of massive stars. In a study led by Rebecca Pitts (University of Florida), scientists have gathered multi-wavelength observations of this nursery, including mid-infrared data from FIFI-LS. The observations reveal the presence of eight very young (around just 7,000 years old), very massive protostars (the largest is ~240 times the mass of the Sun) embedded in the center of the cloud — providing an excellent opportunity to learn about the early stages of massive star formation.

    4
    A zoomed-out (left) and zoomed-in (right) view of NGC 4258’s center, with contours of the [CII] emission superimposed on false-color representations of Hubble data. The [CII] emission is associated with the shocks and turbulence in the galaxy’s jets, which are marked by the line ending in two circles. [Appleton et al. 2018]

    [CII] emission doesn’t just trace star formation! In a study led by Phil Appleton (IPAC/Caltech), scientists have used FIFI-LS’s observations of the active galaxy NGC 4258 to show that [CII] emission is also associated with warm molecular gas and soft X-ray hotspots, both created by shocks and turbulence in the speeding jets launched from the center of an active galaxy. These observations demonstrate that we can use [CII] emission to learn about how these energetic outflows interact with their environments.

    Citation

    ApJL Focus Issue:
    Focus on New Results from SOFIA

    FIFI-LS articles:

    “The Close AGN Reference Survey (CARS): SOFIA Detects Spatially Resolved [C ii] Emission in the Luminous AGN HE 0433-1028,” G. Busch et al. 2018 ApJL 866 L9. doi:10.3847/2041-8213/aae25d
    “A SOFIA Survey of [C ii] in the Galaxy M51. I. [C ii] as a Tracer of Star Formation,” Jorge L. Pineda et al. 2018 ApJL 869 L30. doi:10.3847/2041-8213/aaf1ad
    “Gemini, SOFIA, and ATCA Reveal Very Young, Massive Protostars in the Collapsing Molecular Cloud BYF 73,” Rebecca L. Pitts et al. 2018 ApJL 867 L7. doi:10.3847/2041-8213/aae6ce
    “SOFIA FIFI-LS Observations of Sgr B1: Ionization Structure and Sources of Excitation,” Janet P. Simpson et al. 2018 ApJL 867 L13. doi:10.3847/2041-8213/aae8e4
    “Jet-related Excitation of the [C ii] Emission in the Active Galaxy NGC 4258 with SOFIA,” P. N. Appleton et al. 2018 ApJ 869 61. doi:10.3847/1538-4357/aaed2a

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
  • richardmitnick 11:31 am on May 14, 2019 Permalink | Reply
    Tags: "My GREAT Experience with SOFIA: Part 2", AAS NOVA, , , , , Susanna Kohler   

    From AAS NOVA: “My GREAT Experience with SOFIA: Part 2” 

    AASNOVA

    From AAS NOVA

    14 May 2019
    Susanna Kohler

    1
    AAS Nova editor Susanna Kohler spent a night in the stratosphere flying aboard SOFIA with the German Receiver for Astronomy at Terahertz Frequencies (GREAT) instrument, pictured here. [AAS Nova/S. Kohler]

    In December, AAS Nova Editor Susanna Kohler had the opportunity to fly aboard the NASA/DLR Stratospheric Observatory for Infrared Astronomy (SOFIA) with the German Receiver for Astronomy at Terahertz Frequencies (GREAT) instrument. This week we’re taking a look at that flight, as well as some of the recent science the observatory produced and published in an AAS Journal Focus Issue.

    Susanna Kohler
    14 May 2019

    “It was 6 pm and I was boarding a plane for a 10-hour flight — but there were plenty of signs that this wasn’t your typical redeye.

    For starters, I’d completed rigorous safety training earlier that day that included instructions on how to rappel down from the escape hatch of the cockpit.

    Another sign was the catering (or lack thereof): no little bags of peanuts or lukewarm trays of airplane food. We each brought our own snacks, and we would be eating them cold — the microwave perched above the mini-fridge was off-limits tonight. The instrument currently mounted on the telescope was sensitive to potential leaked radiation from the microwave; no one wanted to be that guy whose nuked burrito ruined the night’s data.

    My travel companions were another indicator that this was no normal flight: there were only 26 other people aboard, most of whom were dressed in flight jumpsuits adorned with mission patches. All of us were bundled up against the slow chill of the 60°F cabin and wearing communication headsets.

    We were aboard SOFIA — the Stratospheric Observatory for Infrared Astronomy — and we were getting ready for a night of flying through the sky, doing infrared astronomy from the stratosphere.

    Auspicious Beginnings

    Takeoff was surprisingly quick: a short taxi and rapid climb into the air. The strangeness of the steep ascent was intensified by my seat: I’d been offered a spot at a console in front of a panel of computers, facing the tail of the plane. I’ve never taken off facing backwards before; I was grateful for the shoulder harness that kept me securely in my seat!

    Onboard as an invited science writer, I had the great fortune of multiple guides on my flight; in addition to communication manager Nicholas Veronico, science outreach lead Randolf Klein flew with me that evening. As we listened in on our headsets to the chatter between the various team members, Randolf acted as my SOFIA translator, clarifying what was happening and what we could expect.

    There’s Science to Be Done!

    We would be observing with the German Receiver for Astronomy at Terahertz Frequencies (GREAT) instrument, and the goals for the night were clearly laid out. We’d begin with a short leg as we flew away from the coast and out over the Pacific, during which the door would open and the telescope would be initialized.

    During our next, 130-minute leg, we would be roughly paralleling California’s coastline, heading as far north as the Oregon border. GREAT — a high-resolution spectrometer — had just been swapped onto SOFIA, so we would use this leg to point southwest at Mars, a known target that could be used to properly align the instrument for the remainder of its flights during this rotation.

    In the next leg, we’d turn southward and point the telescope toward the evolved star U Orionis. On this 37-minute segment, we’d capture spectra to study the physical processes responsible for exciting water masers — emission sources that work like naturally occurring lasers — in the star’s outer shells.

    Next we would swing in the direction of Hawaii and fly roughly three-quarters of the way out to the islands, completing a 125-minute leg observing a specific molecule, deuterated hydroxyl (OD), in a stellar nursery in the Orion A molecular cloud. From these observations, scientists hope to explore the origins of some of the simplest molecules found in our universe.

    Lastly, we’d turn back to the northeast and fly a final long leg home, pointing at the W3 massive star-forming region in Cassiopeia to better understand the emission we see in the HII regions that surround young stars.

    Suspense in the Stratosphere

    The goals may have been clear, but astronomers know that observing never goes exactly as planned.

    For us, the first challenge came early on: shortly into the telescope initialization leg, we hit sudden, strong turbulence. From the chatter in our headsets and the telescope’s view plotted on the console in front of me — which suddenly contained wildly swinging stars rather than the stable targets of moments before — it was clear that something had gone wrong.

    Randolf explained: the turbulence had knocked the telescope into safe mode, and if the team couldn’t quickly reset the scope and complete the instrument alignment before our current leg ended, the entire night’s mission was at risk.

    Thankfully, SOFIA’s team is used to handling challenges under time pressure. Before the leg was up, both the telescope and instrument were set up and aligned, and we all breathed a sigh of relief as the plane turned southwest onto our first science leg.

    A Team Effort

    Watching the data stream in on the screens in front of me that night was an exciting experience. Several of the GREAT team members were armed with laptops and were analyzing the data as fast as it arrived; since spectra can be hard to gauge by eye, real-time computer processing was a must to determine whether the team was getting what they needed.

    Even more fascinating than seeing the data, however, was watching how the different subgroups of the SOFIA team worked together throughout the night to obtain the observations. The onboard team included three pilots, two mission directors, two telescope operators, and nearly a dozen scientists — both instrument and data specialists — associated with GREAT.

    Constant adjustments were needed during the flight: if the pilots were notified of altitude constraints from the FAA, this would be relayed to the mission directors, who might modify the flight plan or observing times; if the scientists weren’t happy with the data they analyzed, they might make requests of the telescope operators or the instrument specialists. Meanwhile, the mission directors kept the team on track with regular announcements about how much time was left in each leg.

    This complex stream of communication between groups took place over many radio channels and in multiple languages, and I found the apparent ease with which the team navigated it oddly beautiful and humbling.

    Window into Our Universe

    As the final observing leg wrapped up, I headed up to the flight deck for a rare opportunity to sit in a 747 cockpit during landing. Chatting with the three pilots — who had more than 300 SOFIA flights under their collective belts — I could tell that they enjoyed being a part of the team. Flying planes is pretty cool, but flying planes for science? That’s something else.

    Our runway lights flicked on, guiding our way to a landing in the quiet California desert. As I looked up through the cockpit glass at the night sky, reflecting on my remarkable flight experience, one thing was clear: SOFIA is an extraordinary window into our universe.

    Check back tomorrow to learn about some of the recent science conducted with SOFIA.”

    *****

    2
    The SOFIA team and a handful of invited guests board the plane before a night in the stratosphere. [AAS Nova/S. Kohler]

    3
    SOFIA’s cabin, facing the rear of the plane. The educator consoles in the foreground allow guests to follow along with the observations. The mission directors sit at the next set of consoles. At the rear of the plane is the solid bulkhead separating the telescope cavity; the GREAT instrument is visible just in front of this, mounted on the back of the telescope. [AAS Nova/S. Kohler]

    4
    Screen capture from flightaware.com of our flight path for the night.

    5
    The Orion A star-forming region, as imaged by Herschel. OMC2 FIR4, the specific region we were exploring with SOFIA tonight, is circled in red. [ESA/Herschel/Ph. André, D. Polychroni, A. Roy, V. Könyves, N. Schneider]

    6
    The telescope operators hard at work during our flight. [AAS Nova/S. Kohler]

    7
    AAS Editor Susanna Kohler after a night flying aboard SOFIA. [AAS Nova/S. Kohler]

    8
    A successful flight! [AAS Nova/S. Kohler]

    Check back tomorrow to learn about some of the recent science conducted with SOFIA.

    See the full article here .


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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    1

    AAS Mission and Vision Statement

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

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

    Adopted June 7, 2009

     
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