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  • richardmitnick 7:59 pm on July 27, 2015 Permalink | Reply
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    From Yale: “Dust pillars of destruction reveal impact of cosmic wind on galaxy evolution” 

    Yale University bloc

    Yale University

    July 27, 2015
    Jim Shelton

    1
    This Hubble Space Telescope image of a spiral galaxy in the Coma cluster highlights dust extinction features. (Image courtesy of NASA, ESA, and Roberto Colombari)

    Astronomers have long known that powerful cosmic winds can sometimes blow through galaxies, sweeping out interstellar material and stopping future star formation. Now they have a clearer snapshot of how it happens.

    A Yale University analysis of one such event in a nearby galaxy provides an unprecedented look at the process. The research is described in the Astronomical Journal.

    Specifically, Yale astronomer Jeffrey Kenney looked at the way the cosmic wind is eroding the gas and dust at the leading edge of the galaxy. The wind, or ram pressure, is caused by the galaxy’s orbital motion through hot gas in the cluster. Kenney found a series of intricate dust formations on the disk’s edge, as cosmic wind began to work its way through the galaxy.

    “On the leading side of the galaxy, all the gas and dust appears to be piled up in one long ridge, or dust front. But you see remarkable, fine scale structure in the dust front,” Kenney explained. “There are head-tail filaments protruding from the dust front. We think these are caused by dense gas clouds becoming separated from lower density gas.”

    Cosmic wind can easily push low-density clouds of interstellar gas and dust, but not high-density clouds. As the wind blows, denser gas lumps start to separate from the surrounding lower density gas which gets blown downstream. But apparently, the high and low-density lumps are partially bound together, most likely by magnetic fields linking distant clouds of gas and dust.

    “The evidence for this is that dust filaments in the HST (Hubble Space Telescope) image look like taffy being stretched out,” Kenney said. “We’re seeing this decoupling, clearly, for the first time.”

    NASA Hubble Telescope
    NASA/ESA HUbble

    2
    The leading side of the disk shows the effects of strong ram pressure. (Image courtesy of NASA, ESA, and Roberto Colombari)

    The analysis is based on Hubble images of a spiral galaxy in the Coma cluster, located 300 million light years from Earth.

    2
    A Sloan Digital Sky Survey/Spitzer Space Telescope mosaic of the Coma Cluster in long-wavelength infrared (red), short-wavelength infrared (green), and visible light. The many faint green smudges are dwarf galaxies in the cluster. Credit: NASA/JPL-Caltech/GSFC/SDSS

    It is the closest high-mass cluster to our solar system. Kenney first saw the images two years ago and realized their possible significance in understanding the way ram pressure strips interstellar material throughout the universe.

    In the 1990s, a famous Hubble photo dubbed “Pillars of Creation” showed columns of dust and gas in the Eagle Nebula that were in the process of forging new stars. The dust filaments Kenney identified are similar in some ways to the “Pillars of Creation,” except they are 1,000 times larger.

    3
    The “Pillars of Creation” in the Eagle Nebula.

    5
    This wide-field image of the Eagle Nebula was taken at the National Science Foundation’s 0.9-meter telescope on Kitt Peak with the NOAO Mosaic CCD camera. Located in the constellation of Serpens, the Serpent, the Eagle Nebula is a very luminous open cluster of stars surrounded by dust and gas. The three pillars at the center of the image, made famous in an image by the Hubble Space Telescope, are being sculpted by the intense radiation from the hot stars in the cluster. This image was created by combining emission-line images in Hydrogen-alpha (green), Oxygen [O III] (blue) and Sulfur [S II] (red).

    In both cases, destruction is at least as important as creation. An external force is pushing away most of the gas and dust, therefore destroying most of the cloud, leaving behind only the most dense material — the pillars. But even the pillars don’t last that long.

    Because gas is the raw material for star formation, its removal stops the creation of new stars and planets. In the Eagle Nebula, the pressure arises from intense radiation emitted by nearby massive stars; in the Coma galaxy, it is pressure from the galaxy’s orbital motion through hot gas in the cluster. Although new stars are being born in both kinds of pillars, we are witnessing, in both, the last generation of stars that will form.

    Much of Kenney’s research has focused on the physical interplay of galaxies with their environment.

    “A great deal of galaxy evolution is driven by interactions,” Kenney said. “Galaxies are shaped by collisions and mergers, as well as this sweeping of their gas from cosmic winds. I’m interested in all of these processes.”

    Kenney’s co-authors on the paper are Yale doctoral student Anne Abramson and Hector-Bravo Alfaro from the Universidad de Guanajuato in Mexico.

    See the full article here.

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    Yale University Campus

    Yale University comprises three major academic components: Yale College (the undergraduate program), the Graduate School of Arts and Sciences, and the professional schools. In addition, Yale encompasses a wide array of centers and programs, libraries, museums, and administrative support offices. Approximately 11,250 students attend Yale.

     
  • richardmitnick 9:06 am on July 26, 2015 Permalink | Reply
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    From Hubble: “Hubble View of a Nitrogen-Rich Nebula” 

    NASA Hubble Telescope

    Hubble

    July 26, 2015
    Editor: Ashley Morrow

    1
    Credit: NASA/ESA Hubble, Matej Novak

    This NASA/ESA Hubble Space Telescope image shows a planetary nebula named NGC 6153, located about 4,000 light-years away in the southern constellation of Scorpius (The Scorpion). The faint blue haze across the frame shows what remains of a star like the sun after it has depleted most of its fuel. When this happens, the outer layers of the star are ejected, and get excited and ionized by the energetic ultraviolet light emitted by the bright hot core of the star, forming the nebula.

    NGC 6153 is a planetary nebula that is elliptical in shape, with an extremely rich network of loops and filaments, shown clearly in this Hubble image. However, this is not what makes this planetary nebula so interesting for astronomers.

    Measurements show that NGC 6153 contains large amounts of neon, argon, oxygen, carbon and chlorine — up to three times more than can be found in the solar system. The nebula contains a whopping five times more nitrogen than our sun! Although it may be that the star developed higher levels of these elements as it grew and evolved, it is more likely that the star originally formed from a cloud of material that already contained a lot more of these elements.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 2:37 pm on July 20, 2015 Permalink | Reply
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    From Hubble: “A galactic nursery” 

    NASA Hubble Telescope

    Hubble

    20 July 2015

    1

    This dramatic image shows the NASA/ESA Hubble Space Telescope’s view of dwarf galaxy known as NGC 1140, which lies 60 million light-years away in the constellation of Eridanus. As can be seen in this image NGC 1140 has an irregular form, much like the Large Magellanic Cloud — a small galaxy that orbits the Milky Way.

    2
    http://ails.arc.nasa.gov/Images/Astrobiology/AC87-0459.html

    This small galaxy is undergoing what is known as a starburst. Despite being almost ten times smaller than the Milky Way it is creating stars at about the same rate, with the equivalent of one star the size of the Sun being created per year. This is clearly visible in the image, which shows the galaxy illuminated by bright, blue-white, young stars.

    Galaxies like NGC 1140 — small, starbursting and containing large amounts of primordial gas with way fewer elements heavier than hydrogen and helium than present in our Sun — are of particular interest to astronomers. Their composition makes them similar to the intensely star-forming galaxies in the early Universe. And these early Universe galaxies were the building blocks of present-day large galaxies like our galaxy, the Milky Way. But, as they are so far away these early Universe galaxies are harder to study so these closer starbursting galaxies are a good substitute for learning more about galaxy evolution .

    The vigorous star formation will have a very destructive effect on this small dwarf galaxy in its future. When the larger stars in the galaxy die, and explode as supernovae, gas is blown into space and may easily escape the gravitational pull of the galaxy. The ejection of gas from the galaxy means it is throwing out its potential for future stars as this gas is one of the building blocks of star formation. NGC 1140’s starburst cannot last for long.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 9:25 pm on July 18, 2015 Permalink | Reply
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    From Hubble: “Hubble Uncovering the Secrets of the Quintuplet Cluster” 

    NASA Hubble Telescope

    Hubble

    July 17, 2015
    Editor: Ashley Morrow

    1

    Although this cluster of stars gained its name due to its five brightest stars, it is home to hundreds more. The huge number of massive young stars in the cluster is clearly captured in this NASA/ESA Hubble Space Telescope image.

    The cluster is located close to the Arches Cluster and is just 100 light-years from the center of our galaxy. The cluster’s proximity to the dust at the center of the galaxy means that much of its visible light is blocked, which helped to keep the cluster unknown until its discovery in 1990, when it was revealed by infrared observations. Infrared images of the cluster, like the one shown here, allow us to see through the obscuring dust to the hot stars in the cluster.

    The Quintuplet Cluster hosts two extremely rare luminous blue variable stars: the Pistol Star and the lesser known V4650 Sgr. If you were to draw a line horizontally through the center of this image from left to right, you could see the Pistol Star hovering just above the line about one third of the way along it. The Pistol Star is one of the most luminous known stars in the Milky Way and takes its name from the shape of the Pistol Nebula that it illuminates, but which is not visible in this infrared image. The exact age and future of the Pistol Star are uncertain, but it is expected to end in a supernova or even a hypernova in one to three million years.

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    Pistol Star
    http://hubblesite.org/newscenter/archive/releases/1997/33/image/a/

    The cluster also contains a number of red supergiants. These stars are among the largest in the galaxy and are burning their fuel at an incredible speed, meaning they will have a very short lifetime. Their presence suggests an average cluster age of nearly four million years. At the moment these stars are on the verge of exploding as supernovae. During their spectacular deaths they will release vast amounts of energy which, in turn, will heat the material — dust and gas — between the other stars.

    This observation shows the Quintuplet Cluster in the infrared and demonstrates the leap in Hubble’s performance since its 1999 image of same object.

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    1999 image. Credit: Don Figer ( Space Telescope Science Institute) and NASA/ESA

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 3:05 pm on June 24, 2015 Permalink | Reply
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    From Hubble: “Hubble Sees a ‘Behemoth’ Bleeding Atmosphere Around a Warm Neptune-Sized Exoplanet” 

    NASA Hubble Telescope

    Hubble

    June 24, 2015
    Felicia Chou
    NASA Headquarters, Washington, D.C.
    202-358-0257
    felicia.chou@nasa.gov

    Ann Jenkins / Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4488 / 410-338-4514
    jenkins@stsci.edu / villard@stsci.edu

    David Ehrenreich
    University of Geneva, Geneva, Switzerland
    011-41-22-379-2390
    david.ehrenreich@unige.ch

    1

    Astronomers using NASA’s Hubble Space Telescope have discovered an immense cloud of hydrogen dubbed “The Behemoth” bleeding off a planet orbiting a nearby star. The enormous, comet-like feature is about 50 times the size of the parent star. The hydrogen is evaporating from a warm, Neptune-sized planet, due to extreme radiation from the star.

    A phenomenon this large has never before been seen around any exoplanet. Given this planet’s small size, it may offer clues to how Hot Super-Earths — massive, rocky, hot versions of Earth — are born around other stars through the evaporation of their outer layers of hydrogen.

    “This cloud is very spectacular, though the evaporation rate does not threaten the planet right now,” explains the study’s leader, David Ehrenreich of the Observatory of the University of Geneva in Switzerland. “But we know that in the past, the star, which is a faint red dwarf, was more active. This means that the planet evaporated faster during its first billion years of existence. Overall, we estimate that it may have lost up to 10 percent of its atmosphere.”

    The planet, named GJ 436b, is considered to be a “Warm Neptune,” because of its size and it is much closer to its star than Neptune is to our sun. Although it is in no danger of having its atmosphere completely evaporated and being stripped down to a rocky core, this planet could explain the existence of so-called Hot Super-Earths that are very close to their stars.

    These hot, rocky worlds were discovered by the Convection Rotation and Planetary Transits (CoRoT) spacecraft (led by the French Space Agency (CNES) in collaboration with ESA (the European Space Agency), and several other international partners), and NASA’s Kepler space telescope. Hot Super-Earths could be the remnants of more massive planets that completely lost their thick, gaseous atmospheres to the same type of evaporation.

    Because Earth’s atmosphere blocks most ultraviolet light, astronomers needed a space telescope with Hubble’s ultraviolet capability and exquisite precision to find “The Behemoth.”

    “You would have to have Hubble’s eyes,” says Ehrenreich. “You would not see it in visible wavelengths. But when you turn the ultraviolet eye of Hubble onto the system, it’s really kind of a transformation, because the planet turns into a monstrous thing.”

    Because the planet’s orbit is tilted nearly edge-on to our view from Earth, the planet can be seen passing in front of its star. Astronomers also saw the star eclipsed by “The Behemoth” hydrogen cloud around the planet.

    Ehrenreich and his team think that such a huge cloud of gas can exist around this planet because the cloud is not rapidly heated and swept away by the radiation pressure from the relatively cool red dwarf star. This allows the cloud to stick around for a longer time. The team’s findings will be published in the June 25 edition of the journal Nature.

    Evaporation such as this may have happened in the earlier stages of our own solar system, when Earth had a hydrogen-rich atmosphere that dissipated over 100 million to 500 million years. If so, Earth may previously have sported a comet-like tail. It’s also possible it could happen to Earth’s atmosphere at the end of our planet’s life, when the sun swells up to become a red giant and boils off our remaining atmosphere, before engulfing our planet completely.

    GJ 436b resides very close to its star — less than 3 million miles — and whips around it in just 2.6 Earth days. (In comparison, Earth is 93 million miles from our sun and orbits it every 365.24 days.) This exoplanet is at least 6 billion years old, and may even be twice that age. It has a mass of around 23 Earths. At just 30 light-years from Earth, it’s one of the closest known extrasolar planets.

    Finding “The Behemoth” could be a game-changer for characterizing atmospheres of the whole population of Neptune-sized planets and Super-Earths in ultraviolet observations. In the coming years, Ehrenreich expects that astronomers will find thousands of this kind of planet.

    The ultraviolet technique used in this study also may spot the signature of oceans evaporating on smaller, more Earth-like planets. It will be extremely challenging for astronomers to directly see water vapor on those worlds, because it’s too low in the atmosphere and shielded from telescopes. However, when water molecules are broken by the stellar radiation into hydrogen and oxygen, the relatively light hydrogen atoms can escape the planet. If scientists could spot this hydrogen evaporating from a planet that is a bit more temperate and little less massive than GJ 436b, that is a good sign of an ocean on the surface.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 7:05 am on June 19, 2015 Permalink | Reply
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    From Hubble: “Quasars in interacting galaxies” 

    NASA Hubble Telescope

    Hubble

    19 June 2015

    1

    Astronomers have used the Hubble Space Telescope’s infrared vision to uncover the mysterious early formative years of quasars, the brightest objects in the universe. Hubble’s sharp images unveil chaotic galaxy collisions that give birth to quasars by fueling their energy source: a supermassive central black hole devouring infalling material.

    “The Hubble observations are definitely telling us that the peak of quasar activity in the early universe is driven by galaxies colliding and then merging together,” said Eilat Glikman of Middlebury College in Vermont. “We are seeing the quasars in their teenage years, when they are growing quickly and all messed up.”

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 1:16 pm on June 12, 2015 Permalink | Reply
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    From NASA Hubble via Goddard: “NASA’s Hubble Telescope Detects ‘Sunscreen’ Layer on Distant Planet” 

    NASA Hubble Telescope

    Hubble

    June 11, 2015

    Felicia Chou
    Headquarters, Washington
    202-358-0257
    felicia.chou@nasa.gov

    Nancy Neal-Jones / Elizabeth Zubritsky
    Goddard Space Flight Center, Greenbelt, Md.
    301-286-0039 / 301-614-5438
    nancy.n.jones@nasa.gov / elizabeth.a.zubritsky@nasa.gov

    Last Updated: June 12, 2015
    Editor: Karen Northon


    Using NASA’s Hubble Telescope, scientists detected a stratosphere on the planet WASP-33b. A stratosphere occurs when molecules in the atmosphere absorb ultraviolet and visible light from the star. This absorption warms the stratosphere and acts as a kind of sunscreen layer for the planet below. This video is public domain and can be downloaded at: http://svs.gsfc.nasa.gov/goto? 11898
    Credits: NASA Goddard

    NASA’s Hubble Space Telescope has detected a stratosphere, one of the primary layers of Earth’s atmosphere, on a massive and blazing-hot exoplanet known as WASP-33b.

    The presence of a stratosphere can provide clues about the composition of a planet and how it formed. This atmospheric layer includes molecules that absorb ultraviolet and visible light, acting as a kind of “sunscreen” for the planet it surrounds. Until now, scientists were uncertain whether these molecules would be found in the atmospheres of large, extremely hot planets in other star systems.

    These findings will appear in the June 12 issue of the Astrophysical Journal.

    “Some of these planets are so hot in their upper atmospheres, they’re essentially boiling off into space,” said Avi Mandell, a planetary scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and a co-author of the study. “At these temperatures, we don’t necessarily expect to find an atmosphere that has molecules that can lead to these multilayered structures.”

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    WASP-33b’s stratosphere was detected by measuring the drop in light as the planet passed behind its star (top). Temperatures in the low stratosphere rise because of molecules absorbing radiation from the star (right). Without a stratosphere, temperatures would cool down at higher altitudes (left). Credits: NASA/Goddard

    In Earth’s atmosphere, the stratosphere sits above the troposphere — the turbulent, active-weather region that reaches from the ground to the altitude where nearly all clouds top out. In the troposphere, the temperature is warmer at the bottom – ground level – and cools down at higher altitudes.

    The stratosphere is just the opposite. In this layer, the temperature increases with altitude, a phenomenon called temperature inversion. On Earth, temperature inversion occurs because ozone in the stratosphere absorbs much of the sun’s ultraviolet radiation, preventing it from reaching the surface, protecting the biosphere, and therefore warming the stratosphere instead.

    Similar temperature inversions occur in the stratospheres of other planets in our solar system, such as Jupiter and Saturn. In these cases, the culprit is a different group of molecules called hydrocarbons. Neither ozone nor hydrocarbons, however, could survive at the high temperatures of most known exoplanets, which are planets outside our solar system. This leads to a debate as to whether stratospheres would exist on them at all.

    Using Hubble, the researchers have settled this debate by identifying a temperature inversion in the atmosphere of WASP-33b, which has about four-and-a-half times the mass of Jupiter. Team members also think they know which molecule in WASP-33b’s atmosphere caused the inversion — titanium oxide.

    “These two lines of evidence together make a very convincing case that we have detected a stratosphere on an exoplanet,” said Korey Haynes, lead author of the study. Haynes was a graduate student at George Mason University in Fairfax, Virginia, and was working at Goddard with Mandell when the research was conducted.

    The researchers analyzed observations made with Hubble’s Wide Field Camera 3 by co-author Drake Deming at the University of Maryland in College Park. Wide Field Camera 3 can capture a spectrum of the near-infrared region where the signature for water appears. Scientists can use the spectrum to identify water and other gases in a distant planet’s atmosphere and determine its temperature.

    Haynes and her colleagues used the Hubble observations, and data from previous studies, to measure emission from water and compare it to emission from gas deeper in the atmosphere. The team determined that emission from water was produced in the stratosphere at about 6,000 degrees Fahrenheit. The rest of the emission came from gas lower in the atmosphere that was at a temperature about 3,000 degrees Fahrenheit.

    The team also presented the first observational evidence that WASP-33b’s atmosphere contains titanium oxide, one of only a few compounds that is a strong absorber of visible and ultraviolet radiation and capable of remaining in gaseous form in an atmosphere as hot as this one.

    “Understanding the links between stratospheres and chemical compositions is critical to studying atmospheric processes in exoplanets,” said co-author Nikku Madhusudhan of the University of Cambridge, United Kingdom. “Our finding marks a key breakthrough in this direction.”

    For images and more information about Hubble, visit:

    http://www.nasa.gov/hubble

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 7:55 am on June 6, 2015 Permalink | Reply
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    From Hubble: “Hubblecast episode 85: Ode to Hubble” 

    NASA Hubble Telescope

    Hubble

    To celebrate Hubble’s 25th birthday ESA/Hubble asked the public to produce and submit short videos illustrating how Hubble has inspired them. This new Hubblecast episode presents the two winning videos. The episode also introduces us to the creators of the videos and they explain how they produced the videos and the inspiration for creating them.

    More information and download options: http://www.spacetelescope.org/videos/…

    Subscribe to Hubblecast in iTunes! https://itunes.apple.com/gb/podcast/h…
    Receive future episodes on YouTube by pressing the Subscribe button above or follow us on Vimeo: https://vimeo.com/hubbleesa

    Watch more Hubblecast episodes: http://www.spacetelescope.org/videos/…

    Find out how to view and contribute subtitles for the Hubblecast in multiple languages, or translate this video on dotSUB: http://www.eso.org/public/outreach/pa…


    Watch, enjoy, learn.

    See the full article here.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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  • richardmitnick 1:43 pm on June 3, 2015 Permalink | Reply
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    From Hubble: “Hubble Finds Two Chaotically Tumbling Pluto Moons” 

    NASA Hubble Telescope

    Hubble

    1
    Pluto and its satellites

    Object Name: Nix, Hydra, Styx, Kerberos
    Object Description: Minor Moons of the Pluto-Charon System
    Properties:
    Discovery Year Semi-major axis (in km) Period (in days)
    Styx 2012 42,700 20.2
    Nix 2005 48,700 24.9
    Kerberos 2011 57,800 32.2
    Hydra 2005 64,800 38.2

    June 3, 2015
    CONTACT

    Ray Villard
    Space Telescope Science Institute, Baltimore, Maryland
    410-338-4514
    villard@stsci.edu

    Felicia Chou
    NASA Headquarters, Washington, D.C.
    202-358-0257
    felicia.chou@nasa.gov

    Mark Showalter
    SETI Institute, Mountain View, California
    605-810-0234
    mshowalter@seti.org

    Doug Hamilton
    University of Maryland, College Park, Maryland
    301-405-1548
    dhamil@astro.umd.edu

    If you lived on one of Pluto’s moons Nix or Hydra, you’d have a hard time setting your alarm clock. That’s because you could not know for sure when, or even in which direction, the sun would rise.

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    Pluto photographed by the New Horizons spacecraft in May 2015

    A comprehensive analysis of all available Hubble Space Telescope data shows that two of Pluto’s moons, Nix and Hydra, are wobbling unpredictably. Scientists believe the other two small moons, Kerberos and Styx, are likely in a similar situation, pending further study.

    “Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm,” said John Grunsfeld, associate administrator of NASA’s Science Mission Directorate in Washington, D.C. “When the New Horizons spacecraft flies through the Pluto system in July we’ll get a chance to see what these moons look like up close and personal.”

    NASA New Horizons spacecraft II
    New Horizons

    Why the chaos? Because the moons are embedded inside a dynamically shifting gravitational field caused by the system’s two central bodies, Pluto and Charon, whirling about each other. The variable gravitational field induces torques that send the smaller moons tumbling in unpredictable ways. This torque is strengthened by the fact the moons are football shaped rather than spherical.

    The surprising results of the Hubble research, conducted by Mark Showalter of the SETI Institute in Mountain View, California, and Doug Hamilton of the University of Maryland at College Park, are appearing in the June 4 issue of the British science journal Nature.

    “Prior to the Hubble observations nobody appreciated the intricate dynamics of the Pluto system,” Showalter said. “Our report provides important new constraints on the sequence of events that led to the formation of the system.”

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    Image of the Plutonian system

    Hubble’s monitoring of Pluto’s four outer moons has also revealed that three of them, Nix, Styx, and Hydra, are presently locked together in resonance where there is a precise ratio among their orbital periods. “This ties together their motion in a way similar to that of three of Jupiter’s large moons,” noted Hamilton. “If you were sitting on Nix you would see that Styx orbits Pluto twice for every three orbits made by Hydra.”

    Hubble provides observational evidence that the satellites are also orbiting chaotically. “However, that does not necessarily mean that the system is on the brink of flying apart,” Showalter added. “We need to know a lot more about the system before we can determine its long-term fate.”

    To the surprise of astronomers, Hubble also found that the moon Kerberos is as dark as a charcoal briquette, while the other satellites are as bright as white sand. It was predicted that pollution by dust blasted off the satellites by meteorite impacts should overcoat all the moons, giving their surfaces a homogeneous look. “This is a very provocative result,” Showalter said.

    NASA’s New Horizons probe, which will fly by the Pluto-Charon system in July 2015, may help settle the question of the asphalt-black moon as well as the other oddities uncovered by Hubble. These new discoveries are being used in the science planning for New Horizons’s observations.

    The chaos in the Pluto-Charon system offers insights into how planets orbiting a double-star might behave. “We are learning that chaos may be a common trait of binary systems,” Hamilton said. “It might even have consequences for life on planets in such systems.” NASA’s Kepler space observatory has found several planetary systems orbiting double stars.

    NASA Kepler Telescope
    Kepler

    Clues to the Pluto chaos first came when astronomers measured variations in the light reflected off of the two moons Nix and Hydra. Their brightness changed unpredictably. “The data were confusing; they made no sense at all. We had an inkling something was fishy,” Showalter said. His team analyzed Hubble images of Pluto taken during 2005-2012. They compared the unpredictable changes in the moons’ reflectivity to dynamical models of spinning bodies in complex gravitational fields.

    Virtually all large moons, as well as small moons in close-in orbits, keep one hemisphere facing their parent planet. This means that the satellite’s rotation is perfectly matched to the orbital period. This is not coincidental, but the consequence of gravitational tides between moon and planet. (Hyperion, which orbits Saturn, is the only other solar-system example of chaotic rotation; it is due to the combined gravitational tugs of the planet and it largest moon, Titan).

    Pluto’s moons are hypothesized to have formed by a collision between the dwarf planet and another similar-sized body early in the history of the solar system. The smashup flung material that coalesced into the family of satellites observed around Pluto today. Its large binary companion, Charon, was discovered in 1978. The object is almost half the size of Pluto. Hubble discovered Nix and Hydra in 2005, Kerberos in 2011, and Styx in 2012. These little moons, measuring just tens of miles across, were found as part of a Hubble search for potential hazards to the New Horizons spacecraft flyby.

    Pluto and Charon are called a double planet because they orbit about a common center of gravity that is located in the space between the bodies. Some regard the Earth-moon system as a double planet, too, although the center of gravity falls beneath Earth’s surface. (Our moon has 1/80th of Earth’s mass, whereas Charon has 1/8th of Pluto’s mass.)

    Researchers say that a combination of monitoring data from Hubble, New Horizons’s brief close-up look, and eventually, observations with the James Webb Space Telescope will help settle many mysteries of the Pluto-Charon system. No ground-based telescopes have yet been able to detect the smallest moons.

    NASA Webb Telescope
    Webb

    “Pluto will continue to surprise us when New Horizons flies past it in July,” Showalter said. “Our work with the Hubble telescope just gives us a foretaste of what’s in store.”

    See the full article here.

    Please help promote STEM in your local schools.

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    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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    • Matthew Wright 6:41 pm on June 3, 2015 Permalink | Reply

      Awesome stuff. It’s amazong what can be calculated from partial data. I figure this is a taster for the flood of info we’ll get about the Pluto system in a few months. And then will come the years of analysis which may well reveal other left-field discoveries about Pluto.

      Like

  • richardmitnick 11:43 am on June 2, 2015 Permalink | Reply
    Tags: , , NASA/ESA Hubble,   

    From Hubble: “Merging galaxies break radio silence” 

    NASA Hubble Telescope

    Hubble

    28 May 2015
    Contacts
    Marco Chiaberge
    Space Telescope Science Institute, USA
    Johns Hopkins University, USA, INAF-IRA, Italy
    Tel: +1 410 338 4980
    Email: marcoc@stsci.edu

    Roberto Gilli
    INAF
    Osservatorio Astronomico di Bologna, Italy
    Tel: +39 051 2095 719
    Cell: +39 347 4139847
    Email: roberto.gilli@oabo.inaf.it

    Mathias Jäger
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Cell: +49 176 62397500
    Email: mjaeger@partner.eso.org

    1

    In the most extensive survey of its kind ever conducted, a team of scientists have found an unambiguous link between the presence of supermassive black holes that power high-speed, radio-signal-emitting jets and the merger history of their host galaxies. Almost all of the galaxies hosting these jets were found to be merging with another galaxy, or to have done so recently. The results lend significant weight to the case for jets being the result of merging black holes and will be presented in the Astrophysical Journal.

    A team of astronomers using the NASA/ESA Hubble Space Telescope’s Wide Field Camera 3 (WFC3) have conducted a large survey to investigate the relationship between galaxies that have undergone mergers and the activity of the supermassive black holes at their cores.

    NASA Hubble WFC3
    WFC3

    The team studied a large selection of galaxies with extremely luminous centres — known as active galactic nuclei (AGNs) — thought to be the result of large quantities of heated matter circling around and being consumed by a supermassive black hole. Whilst most galaxies are thought to host a supermassive black hole, only a small percentage of them are this luminous and fewer still go one step further and form what are known as relativistic jets [1]. The two high-speed jets of plasma move almost with the speed of light and stream out in opposite directions at right angles to the disc of matter surrounding the black hole, extending thousands of light-years into space. The hot material within the jets is also the origin of radio waves.

    It is these jets that Marco Chiaberge from the Space Telescope Science Institute, USA (also affiliated with Johns Hopkins University, USA and INAF-IRA, Italy) and his team hoped to confirm were the result of galactic mergers [2].

    The team inspected five categories of galaxies for visible signs of recent or ongoing mergers — two types of galaxies with jets, two types of galaxies that had luminous cores but no jets, and a set of regular inactive galaxies [3].

    “The galaxies that host these relativistic jets give out large amounts of radiation at radio wavelengths,” explains Marco. “By using Hubble’s WFC3 camera we found that almost all of the galaxies with large amounts of radio emission, implying the presence of jets, were associated with mergers. However, it was not only the galaxies containing jets that showed evidence of mergers!” [4].

    “We found that most merger events in themselves do not actually result in the creation of AGNs with powerful radio emission,” added co-author Roberto Gilli from Osservatorio Astronomico di Bologna, Italy. “About 40% of the other galaxies we looked at had also experienced a merger and yet had failed to produce the spectacular radio emissions and jets of their counterparts.”

    Although it is now clear that a galactic merger is almost certainly necessary for a galaxy to host a supermassive black hole with relativistic jets, the team deduce that there must be additional conditions which need to be met. They speculate that the collision of one galaxy with another produces a supermassive black hole with jets when the central black hole is spinning faster — possibly as a result of meeting another black hole of a similar mass — as the excess energy extracted from the black hole’s rotation would power the jets.

    “There are two ways in which mergers are likely to affect the central black hole. The first would be an increase in the amount of gas being driven towards the galaxy’s centre, adding mass to both the black hole and the disc of matter around it,” explains Colin Norman, co-author of the paper. “But this process should affect black holes in all merging galaxies, and yet not all merging galaxies with black holes end up with jets, so it is not enough to explain how these jets come about. The other possibility is that a merger between two massive galaxies causes two black holes of a similar mass to also merge. It could be that a particular breed of merger between two black holes produces a single spinning supermassive black hole, accounting for the production of jets.”

    Future observations using both Hubble and the Atacama Large Millimeter/submillimeter Array (ALMA) are needed to expand the survey set even further and continue to shed light on these complex and powerful processes.

    ALMA Array
    ALMA

    Notes

    [1] Relativistic jets travel at close to the speed of light, making them one of the fastest astronomical objects known.

    [2] The new observations used in this research were taken in collaboration with the 3CR-HST team. This international team of astronomers is currently led by Marco Chiaberge and has conducted a series of surveys of radio galaxies and quasars from the 3CR catalogue using the Hubble Space Telescope.

    [3] The team compared their observations with the swathes of archival data from Hubble. They directly surveyed twelve very distant radio galaxies and compared the results with data from a large number of galaxies observed during other observing programmes.

    [4] Other studies had shown a strong relationship between the merger history of a galaxy and the high levels of radiation at radio wavelengths that suggests the presence of relativistic jets lurking at the galaxy’s centre. However, this survey is much more extensive, and the results very clear, meaning it can now be said with almost certainty that radio-loud AGNs, that is, galaxies with relativistic jets, are the result of galactic mergers.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    The Hubble Space Telescope is a project of international cooperation between NASA and the European Space Agency. NASA’s Goddard Space Flight Center manages the telescope. The Space Telescope Science Institute (STScI), is a free-standing science center, located on the campus of The Johns Hopkins University and operated by the Association of Universities for Research in Astronomy (AURA) for NASA, conducts Hubble science operations.

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