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  • richardmitnick 3:38 pm on April 24, 2015 Permalink | Reply
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    From Hubble: The 25th Anniversary Image – Hubblecast 82 

    NASA Hubble Telescope

    Hubble

    This Hubblecast explores the new image of star cluster Westerlund 2, taken by the NASA/ESA Hubble Space telescope and released to celebrate its 25th year in orbit.

    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 2:05 pm on April 23, 2015 Permalink | Reply
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    From Hubble: “Celestial fireworks celebrate Hubble’s 25th anniversary” 

    NASA Hubble Telescope

    Hubble

    23 April 2015
    Georgia Bladon
    ESA/Hubble, Public Information Officer
    Garching, Germany
    Cell: +44 7816291261
    Email: gbladon@partner.eso.org

    Ray Villard
    Space Telescope Science Institute
    Baltimore, USA
    Tel: +1-410-338-4514
    Email: villard@stsci.edu

    1

    The glittering tapestry of young stars flaring to life in this new NASA/ESA Hubble Space Telescope image aptly resembles an exploding shell in a fireworks display. This vibrant image of the star cluster Westerlund 2 has been released to celebrate Hubble’s 25th year in orbit and a quarter of a century of new discoveries, stunning images and outstanding science.

    On 24 April 1990 the NASA/ESA Hubble Space Telescope was sent into orbit aboard the space shuttle Discovery as the first space telescope of its kind. It offered a new view of the Universe and has, for 25 years, reached and surpassed all expectations, beaming back data and images that have changed scientists’ understanding of the Universe and the public’s perception of it.

    In this image, the sparkling centrepiece of Hubble’s silver anniversary fireworks is a giant cluster of about 3000 stars called Westerlund 2 [1][2]. The cluster resides in a raucous stellar breeding ground known as Gum 29, located 20 000 light-years away in the constellation Carina.

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    Gum 29

    4
    Detail of NGC 3372 taken by the VLT telescope
    Credit: ESO

    ESO VLT Interferometer
    ESO/VLT

    The stellar nursery is difficult to observe because it is surrounded by dust, but Hubble’s Wide Field Camera 3 peered through the dusty veil in near-infrared light, giving astronomers a clear view of the cluster.

    NASA Hubble WFC3
    WFC3

    Hubble’s sharp vision resolves the dense concentration of stars in the central cluster, which measures only about 10 light-years across.

    The giant star cluster is only about two million years old, but contains some of the brightest, hottest and most massive stars ever discovered. Some of the heftiest stars are carving deep cavities in the surrounding material by unleashing torrents of ultraviolet light and high speed streams of charged particles, known as stellar winds. These are etching away the enveloping hydrogen gas cloud in which the stars were born and are responsible for the weird and wonderful shapes of the clouds of gas and dust in the image.

    The pillars in the image are composed of dense gas and dust, and are resisting erosion from the fierce radiation and powerful winds. These gaseous monoliths are a few light-years tall and point to the central cluster. Other dense regions surround the pillars, including dark filaments of dust and gas.

    Besides sculpting the gaseous terrain, the brilliant stars can also help create a succeeding generation of offspring. When the stellar winds hit dense walls of gas, they create shocks, which generate a new wave of star birth along the wall of the cavity. The red dots scattered throughout the landscape are a rich population of forming stars that are still wrapped in their gas and dust cocoons. These stellar foetuses have not yet ignited the hydrogen in their cores to light-up as stars. However, Hubble’s near-infrared vision allows astronomers to identify these fledglings. The brilliant blue stars seen throughout the image are mostly in the foreground.

    The image’s central region, containing the star cluster, blends visible-light data taken by the Advanced Camera for Surveys and near-infrared exposures taken by the Wide Field Camera 3. The surrounding region is composed of visible-light observations taken by the Advanced Camera for Surveys.

    This image is a testament to Hubble’s observational power and demonstrates that, even with 25 years of operations under its belt, Hubble’s story is by no means over. Hubble has set the stage for its companion the James Webb Space Telescope — scheduled for launch in 2018 — but will not be immediately replaced by this new feat of engineering, instead working alongside it. Now, 25 years after launch, is the time to celebrate Hubble’s future potential as well as its remarkable history.

    NASA James Webb Telescope
    NASA/Webb

    Notes

    [1] A new anniversary image is released every year; last year Hubble snapped the ethereal Monkey Head Nebula (heic1406).

    5
    Monkey Head Nebula

    The year 2013 saw the release of a strikingly delicate view of the Horsehead Nebula (heic1307), and Hubble’s 22nd year was marked by a huge mosaic of a celestial spider (heic1206)! Other images include a multicoloured view of Saturn (opo9818a), a Tolkien-esque shot of the Carina Nebula (heic1007a), and a beautiful cosmic rose made up of merging galaxies (heic1107a). More anniversary images can be seen here.

    6
    Horsehead Nebula

    7
    30 Doradus

    8
    Carina Nebula

    9
    Arp 273

    [2] Westerlund 2 is named after Swedish astronomer Bengt Westerlund, who discovered the grouping in the 1960s.

    Image credit: NASA, ESA, the Hubble Heritage Team (STScI/AURA), A. Nota (ESA/STScI), and the Westerlund 2 Science Team

    The original observations of Westerlund 2 were obtained by the science team: Antonella Nota (ESA/STScI), Elena Sabbi (STScI), Eva Grebel and Peter Zeidler (Astronomisches Rechen-Institut Heidelberg), Monica Tosi (INAF, Osservatorio Astronomico di Bologna), Alceste Bonanos (National Observatory of Athens, Astronomical Institute), Carol Christian (STScI/AURA) and Selma de Mink (University of Amsterdam). Follow-up observations were made by the Hubble Heritage team: Zoltan Levay (STScI), Max Mutchler, Jennifer Mack, Lisa Frattare, Shelly Meyett, Mario Livio, Carol Christian (STScI/AURA), and Keith Noll (NASA/GSFC).

    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 3:17 pm on April 16, 2015 Permalink | Reply
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    From ESO: “Giant Galaxies Die from the Inside Out” 


    European Southern Observatory

    16 April 2015
    Sandro Tacchella
    ETH Zurich
    Zurich, Switzerland
    Tel: +41 44 633 6314
    Cell: +41 76 480 7963
    Email: sandro.tacchella@phys.ethz.ch

    Marcella Carollo
    ETH Zurich
    Zurich, Switzerland
    Tel: +41 797 926 581
    Email: marcella@phys.ethz.ch

    Richard Hook
    ESO, Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    VLT and Hubble observations show that star formation shuts down in the centres of elliptical galaxies first

    Temp 1

    Astronomers have shown for the first time how star formation in “dead” galaxies sputtered out billions of years ago. ESO’s Very Large Telescope and the NASA/ESA Hubble Space Telescope have revealed that three billion years after the Big Bang, these galaxies still made stars on their outskirts, but no longer in their interiors. The quenching of star formation seems to have started in the cores of the galaxies and then spread to the outer parts. The results will be published in the 17 April 2015 issue of the journal Science.

    A major astrophysical mystery has centred on how massive, quiescent elliptical galaxies, common in the modern Universe, quenched their once furious rates of star formation. Such colossal galaxies, often also called spheroids because of their shape, typically pack in stars ten times as densely in the central regions as in our home galaxy, the Milky Way, and have about ten times its mass.

    Astronomers refer to these big galaxies as red and dead as they exhibit an ample abundance of ancient red stars, but lack young blue stars and show no evidence of new star formation. The estimated ages of the red stars suggest that their host galaxies ceased to make new stars about ten billion years ago. This shutdown began right at the peak of star formation in the Universe, when many galaxies were still giving birth to stars at a pace about twenty times faster than nowadays.

    “Massive dead spheroids contain about half of all the stars that the Universe has produced during its entire life,” said Sandro Tacchella of ETH Zurich in Switzerland, lead author of the article. “We cannot claim to understand how the Universe evolved and became as we see it today unless we understand how these galaxies come to be.”

    Tacchella and colleagues observed a total of 22 galaxies, spanning a range of masses, from an era about three billion years after the Big Bang [1]. The SINFONI instrument on ESO’s Very Large Telescope (VLT) collected light from this sample of galaxies, showing precisely where they were churning out new stars. SINFONI could make these detailed measurements of distant galaxies thanks to its adaptive optics system, which largely cancels out the blurring effects of Earth’s atmosphere.

    ESO SINFONI
    SINFONI

    The researchers also trained the NASA/ESA Hubble Space Telescope on the same set of galaxies, taking advantage of the telescope’s location in space above our planet’s distorting atmosphere. Hubble’s WFC3 camera snapped images in the near-infrared, revealing the spatial distribution of older stars within the actively star-forming galaxies.

    NASA Hubble Telescope
    NASA/ESA Hubble

    “What is amazing is that SINFONI’s adaptive optics system can largely beat down atmospheric effects and gather information on where the new stars are being born, and do so with precisely the same accuracy as Hubble allows for the stellar mass distributions,” commented Marcella Carollo, also of ETH Zurich and co-author of the study.

    According to the new data, the most massive galaxies in the sample kept up a steady production of new stars in their peripheries. In their bulging, densely packed centres, however, star formation had already stopped.

    “The newly demonstrated inside-out nature of star formation shutdown in massive galaxies should shed light on the underlying mechanisms involved, which astronomers have long debated,” says Alvio Renzini, Padova Observatory, of the Italian National Institute of Astrophysics.

    A leading theory is that star-making materials are scattered by torrents of energy released by a galaxy’s central supermassive black hole as it sloppily devours matter. Another idea is that fresh gas stops flowing into a galaxy, starving it of fuel for new stars and transforming it into a red and dead spheroid.

    “There are many different theoretical suggestions for the physical mechanisms that led to the death of the massive spheroids,” said co-author Natascha Förster Schreiber, at the Max-Planck-Institut für extraterrestrische Physik in Garching, Germany. “Discovering that the quenching of star formation started from the centres and marched its way outwards is a very important step towards understanding how the Universe came to look like it does now.”

    Notes

    [1] The Universe’s age is about 13.8 billion years, so the galaxies studied by Tacchella and colleagues are generally seen as they were more than 10 billion years ago.
    More information

    This research was presented in a paper entitled Evidence for mature bulges and an inside-out quenching phase 3 billion years after the Big Bang by S. Tacchella et al., to appear in the journal Science on 17 April 2015.

    The team is composed of Sandro Tacchella (ETH Zurich, Switzerland), Marcella Carollo (ETH Zurich), Alvio Renzini (Italian National Institute of Astrophysics, Padua, Italy), Natascha Förster Schreiber (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), Philipp Lang (Max-Planck-Institut für Extraterrestrische Physik), Stijn Wuyts (Max-Planck-Institut für Extraterrestrische Physik), Giovanni Cresci (Istituto Nazionale di Astrofisica), Avishai Dekel (The Hebrew University, Israel), Reinhard Genzel (Max-Planck-Institut für extraterrestrische Physik and University of California, Berkeley, California, USA), Simon Lilly (ETH Zurich), Chiara Mancini (Italian National Institute of Astrophysics), Sarah Newman (University of California, Berkeley, California, USA), Masato Onodera (ETH Zurich), Alice Shapley (University of California, Los Angeles, USA), Linda Tacconi (Max-Planck-Institut für Extraterrestrische Physik, Garching, Germany), Joanna Woo (ETH Zurich) and Giovanni Zamorani (Italian National Institute of Astrophysics, Bologna, Italy).

    See the full article here.

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    ESO is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

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  • richardmitnick 9:04 am on April 6, 2015 Permalink | Reply
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    From Hubble: “The crammed centre of Messier 22″ 

    NASA Hubble Telescope

    Hubble

    6 April 2015

    1
    NASA/ESA Hubble
    Hubble Space Telescope ACS

    NASA Hubble ACS
    ACS

    This image shows the centre of the globular cluster Messier 22, also known as M22, as observed by the NASA/ESA Hubble Space Telescope. Globular clusters are spherical collections of densely packed stars, relics of the early years of the Universe, with ages of typically 12 to 13 billion years. This is very old considering that the Universe is only 13.8 billion years old.

    Messier 22 is one of about 150 globular clusters in the Milky Way and at just 10 000 light-years away it is also one of the closest to Earth. It was discovered in 1665 by Abraham Ihle, making it one of the first globulars ever to be discovered. This is not so surprising as it is one of the brightest globular clusters visible from the northern hemisphere, located in the constellation of Sagittarius, close to the Galactic Bulge — the dense mass of stars at the centre of the Milky Way.

    3
    Galactic bulge of Milky Way depicted

    The cluster has a diameter of about 70 light-years and, when looking from Earth, appears to take up a patch of sky the size of the full Moon. Despite its relative proximity to us, the light from the stars in the cluster is not as bright as it should be as it is dimmed by dust and gas located between us and the cluster.

    As they are leftovers from the early Universe, globular clusters are popular study objects for astronomers. M22 in particular has fascinating additional features: six planet-sized objects that are not orbiting a star have been detected in the cluster, it seems to host two black holes, and the cluster is one of only three ever found to host a planetary nebula — a short-lived gaseous shells ejected by massive stars at the ends of their lives.

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    The Hubble Space Telescope captured this beautiful image of NGC 6326, a planetary nebula with glowing wisps of outpouring gas that are lit up by a central star nearing the end of its life. When a star ages and the red giant phase of its life comes to an end, it starts to eject layers of gas from its surface leaving behind a hot and compact white dwarf. Sometimes this ejection results in elegantly symmetric patterns of glowing gas, but NGC 6326 is much less structured. This object is located in the constellation of Ara, the Altar, about 11 000 light-years from Earth.

    Planetary nebulae are one of the main ways in which elements heavier than hydrogen and helium are dispersed into space after their creation in the hearts of stars. Eventually some of this outflung material may form new stars and planets. The vivid red and blue hues in this image come from the material glowing under the action of the fierce ultraviolet radiation from the still hot central star.
    This picture was created from images taken using the Hubble Space Telescope’s Wide Field Planetary Camera 2 [WFPC2].

    NASA Hubble WFPC2
    WFPC2

    The red light was captured through a filter letting through the glow from hydrogen gas (F658N). The blue glow comes from ionised oxygen and was recorded through a green filter (F502N). The green layer of the image, which shows the stars well, was taken through a broader yellow filter (F555W). The total exposure times were 1400 s, 360 s and 260 s respectively. The field of view is about 30 arcseconds across.
    Date 28 June 2010

    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 4:13 pm on April 2, 2015 Permalink | Reply
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    From Hubble: “Hubble finds ghosts of quasars past” 

    NASA Hubble Telescope

    Hubble

    2 April 2015
    William Keel
    University of Alabama
    Tuscaloosa, Alabama, USA
    Tel: +1-205-348-1641
    Email: wkeel@ua.edu

    Ray Villard
    Space Telescope Science Institute
    Baltimore, Maryland, USA
    Tel: +1-410-338-4514
    Email: villard@stsci.edu

    Georgia Bladon
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Tel: +44 7816291261
    Email: gbladon@partner.eso.org

    1
    Image credit: NASA, ESA, Galaxy Zoo team & W. Keel (University of Alabama, USA)

    The NASA/ESA Hubble Space Telescope has imaged a set of enigmatic quasar ghosts — ethereal green objects which mark the graves of these objects that flickered to life and then faded. The eight unusual looped structures orbit their host galaxies and glow in a bright and eerie goblin-green hue. They offer new insights into the turbulent pasts of these galaxies.

    The ethereal wisps in these images were illuminated, perhaps briefly, by a blast of radiation from a quasar — a very luminous and compact region that surrounds a supermassive black hole at the centre of a galaxy. Galactic material falls inwards towards the central black hole, growing hotter and hotter, forming a bright and brilliant quasar with powerful jets of particles and energy beaming above and below the disc of infalling matter.

    In each of these eight images a quasar beam has caused once-invisible filaments in deep space to glow through a process called photoionization. Oxygen, helium, nitrogen, sulphur and neon in the filaments absorb light from the quasar and slowly re-emit it over many thousands of years. Their unmistakable emerald hue is caused by ionised oxygen, which glows green.

    These ghostly structures are so far from the galaxy’s heart that it would have taken light from the quasar tens of thousands of years to reach them and light them up. So, although the quasars themselves have turned off, the green clouds will continue to glow for much longer before they too fade.

    Not only are the green filaments far from the centres of their host galaxies, they are also immense in size, spanning tens of thousands of light-years. They are thought to be long tails of gas formed during a violent past merger between galaxies — this event would have caused strong gravitational forces that would rip apart the galactic participants.

    Despite their turbulent past, these ghostly filaments are now leisurely orbiting within or around their new host galaxies. These Hubble images show bright, braided and knotted streams of gas, in some cases connected to twisted lanes of dark dust.

    Galactic mergers do not just alter the forms of the previously serene galaxies involved; they also trigger extreme cosmic phenomena. Such a merger could also have caused the birth of a quasar, by pouring material into the galaxies’ supermassive black holes.

    The first object of this type was found in 2007 by Dutch schoolteacher Hanny van Arkel (heic1102). She discovered the ghostly structure in the online Galaxy Zoo project, a project enlisting the help of the public to classify more than a million galaxies catalogued in the Sloan Digital Sky Survey (SDSS). The bizarre feature was dubbed Hanny’s Voorwerp (Dutch for Hanny’s object).

    Sloan Digital Sky Survey Telescope
    SDSS telescope at Apache Point. NM, USA

    These objects were found in a spin-off of the Galaxy Zoo project, in which about 200 volunteers examined over 16 000 galaxy images in the SDSS to identify the best candidates for clouds similar to Hanny’s Voorwerp. A team of researchers analysed these and found a total of twenty galaxies that had gas ionised by quasars. Their results appear in a paper in the Astronomical Journal.

    Those featured here are (from left to right on top row) the Teacup (more formally known as 2MASX J14302986+1339117), NGC 5972, 2MASX J15100402+0740370 and UGC 7342, and (from left to right on bottom row) NGC 5252, Mrk 1498, UGC 11185 and 2MASX J22014163+1151237.

    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 6:40 am on March 28, 2015 Permalink | Reply
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    From Hubble: “Hubblecast 83″ 

    NASA Hubble Telescope

    Hubble

    March 19, 2015

    As Hubble enters its 25th year in orbit, with celebrations planned around the world for its anniversary on 24 April 2015, this Hubblecast celebrates the relationship that the telescope will have with its future colleague, the James Webb Space Telescope.

    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 1:57 pm on March 26, 2015 Permalink | Reply
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    From Hubble: “Dark matter even darker than once thought” 

    NASA Hubble Telescope

    Hubble

    26 March 2015
    David Harvey
    École Polytechnique Fédérale de Lausanne
    Lausanne, Switzerland
    Tel: +41 22 3792475
    Cell: +41 7946 38283
    Email: david.harvey@epfl.ch

    Richard Massey
    Durham University
    Durham, UK
    Tel: +44 7740 648080
    Email: r.j.massey@durham.ac.uk

    Georgia Bladon
    ESA/Hubble, Public Information Officer
    Garching bei München, Germany
    Tel: +44 7816 291261
    Email: gbladon@partner.eso.org

    Hubble explores the dark side of cosmic collisions

    1
    Image credit: NASA, ESA, D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland)and R. Massey (Durham University, UK)

    Astronomers using observations from the NASA/ESA Hubble Space Telescope and NASA’s Chandra X-ray Observatory have studied how dark matter in clusters of galaxies behaves when the clusters collide. The results, published in the journal Science on 27 March 2015, show that dark matter interacts with itself even less than previously thought, and narrows down the options for what this mysterious substance might be.

    NASA Chandra Telescope
    NASA/CHandra

    Dark matter is a giant question mark looming over our knowledge of the Universe. There is more dark matter in the Universe than visible matter, but it is extremely elusive; it does not reflect, absorb or emit light, making it invisible. Because of this, it is only known to exist via its gravitational effects on the visible Universe (see e.g. heic1215a).

    To learn more about this mysterious substance, researchers can study it in a way similar to experiments on visible matter — by watching what happens when it bumps into things [1]. For this reason, researchers look at vast collections of galaxies, called galaxy clusters, where collisions involving dark matter happen naturally and where it exists in vast enough quantities to see the effects of collisions [2].

    Galaxies are made of three main ingredients: stars, clouds of gas and dark matter. During collisions, the clouds of gas spread throughout the galaxies crash into each other and slow down or stop. The stars are much less affected by the drag from the gas [3] and, because of the huge gaps between them, do not have a slowing effect on each other — though if two stars did collide the frictional forces would be huge.

    “We know how gas and stars react to these cosmic crashes and where they emerge from the wreckage. Comparing how dark matter behaves can help us to narrow down what it actually is,” explains David Harvey of the École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland, lead author of a new study.

    Harvey and his team used data from the NASA/ESA Hubble Space Telescope and NASA’s Chandra X-ray Observatory to study 72 large cluster collisions. The collisions happened at different times, and are seen from different angles — some from the side, and others head-on [4].

    The team found that, like the stars, the dark matter continued straight through the violent collisions without slowing down. However, unlike in the case of the stars, this is not because the dark matter is far away from other dark matter during the collisions. The leading theory is that dark matter is spread evenly throughout the galaxy clusters so dark matter particles frequently get very close to each other. The reason the dark matter doesn’t slow down is because not only does it not interact with visible particles, it also interacts even less with other dark matter than previously thought.

    “A previous study had seen similar behaviour in the Bullet Cluster,” says team member Richard Massey of Durham University, UK.

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    Bullet Cluster
    X-ray photo by Chandra X-ray Observatory. Exposure time was 140 hours. The scale is shown in megaparsecs. Redshift (z) = 0.3, meaning its light has wavelengths stretched by a factor of 1.3.

    “But it’s difficult to interpret what you’re seeing if you have just one example. Each collision takes hundreds of millions of years, so in a human lifetime we only get to see one freeze-frame from a single camera angle. Now that we have studied so many more collisions, we can start to piece together the full movie and better understand what is going on.”

    By finding that dark matter interacts with itself even less than previously thought, the team have successfully narrowed down the properties of dark matter. Particle physics theorists have to keep looking, but they now have a smaller set of unknowns to work with when building their models[5].

    Dark matter could potentially have rich and complex properties, and there are still several other types of interaction to study. These latest results rule out interactions that create a strong frictional force, causing dark matter to slow down during collisions. Other possible interactions could make dark matter particles bounce off each other like billiard balls, causing dark matter to be thrown out of collisions or for dark matter blobs to change shape. The team will be studying these next.

    To further increase the number of collisions that can be studied, the team are also looking to study collisions involving individual galaxies, which are much more common.

    “There are still several viable candidates for dark matter, so the game is not over, but we are getting nearer to an answer,” concludes Harvey. “These ‘Astronomically Large’ particle colliders are finally letting us glimpse the dark world all around us but just out of reach.”

    Notes

    [1] On Earth scientists use particle accelerators to find out more about the properties of different particles. Physicists can investigate what substances are made of by accelerating particles into a collision, and examining the properties and trajectory of the resulting debris.

    [2] Clusters of galaxies are a swarm of galaxies permeated by a sea of hot X-ray emitting ionised hydrogen gas that is all embedded in a massive cloud of dark matter. It is the interactions of these, the most massive structures in the Universe that are observed to test dark matter’s properties.

    [3] The gas-gas interaction in cluster collisions is very strong, while the gas-star drag is weak. In a similar way to a soap bubble and a bullet in the wind where the bubble would interact a great deal more with the wind than the bullet.

    [4] To find out where the dark matter was located in the cluster the researchers studied the light from galaxies behind the cluster whose light had been magnified and distorted by the mass in the cluster. Because they have a good idea of the visible mass in the cluster, the amount the light is distorted tells them how much dark matter there is in a region.

    [5] A favoured theory is that dark matter might be constituted of “supersymmetric” particles. Supersymmetry is a theory in which all particles in our Standard Model — electrons, protons, neutrons, and so on — have a more massive “supersymmetric” partner. While there has been no experimental confirmation for supersymmetry as yet, the theory would solve a few of the gaps in our current thinking. One of supersymmetry’s proposed particles would be stable, electrically neutral, and only interact weakly with the common particles of the Standard Model — all the properties required to explain dark matter.

    Supersymmetry standard model
    Standard Model of Supersymmetry

    4
    Standard Model of Particle Physics. The diagram shows the elementary particles of the Standard Model (the Higgs boson, the three generations of quarks and leptons, and the gauge bosons), including their names, masses, spins, charges, chiralities, and interactions with the strong, weak and electromagnetic forces. It also depicts the crucial role of the Higgs boson in electroweak symmetry breaking, and shows how the properties of the various particles differ in the (high-energy) symmetric phase (top) and the (low-energy) broken-symmetry phase (bottom).

    Notes for editors

    The research paper, entitled The non-gravitational interactions of dark matter in colliding galaxy clusters, will be published in the journal Science on 27 March 2015.

    The international team of astronomers in this study consists of D. Harvey (École Polytechnique Fédérale de Lausanne, Switzerland; University of Edinburgh, UK), R. Massey (Durham University, UK), T. Kitching (University College London, UK), A. Taylor (University of Edinburgh, UK), and E. Tittley (University of Edinburgh, UK).
    More information

    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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  • richardmitnick 9:29 am on March 24, 2015 Permalink | Reply
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    From Hubble: “Hubble Explores the Mysteries of UGC 8201″ 

    NASA Hubble Telescope

    Hubble

    1

    The galaxy UGC 8201, captured here by the NASA/ESA Hubble Space Telescope, is a dwarf irregular galaxy, so called because of its small size and chaotic structure. It lies just under 15 million light-years away from us in the constellation of Draco (the Dragon). As with most dwarf galaxies it is a member of a larger group of galaxies. In this case UCG 8201 is part of the M81 galaxy group; this group is one of the closest neighbors to the Local Group of galaxies, which contains our galaxy, the Milky Way.

    2
    The spiral galaxy Messier 81 is tilted at an oblique angle on to our line of sight, giving a “birds-eye view” of the spiral structure. The galaxy is similar to our Milky Way, but our favorable view provides a better picture of the typical architecture of spiral galaxies. Though the galaxy is 11.6 million light-years away, NASA Hubble Space Telescope’s view is so sharp that it can resolve individual stars, along with open star clusters, globular star clusters, and even glowing regions of fluorescent gas.

    4
    Local Group

    UGC 8201 is at an important phase in its evolution. It has recently finished a long period of star formation, which had significant impact on the whole galaxy. This episode lasted for several hundred million years and produced a high number of newborn bright stars. These stars can be seen in this image as the dominating light source within the galaxy. This process also changed the distribution and amount of dust and gas in between the stars in the galaxy.

    Such large star formation events need extensive sources of energy to trigger them. However, compared to larger galaxies, dwarf galaxies lack such sources and they do not appear to have enough gas to produce as many new stars as they do. This raises an important unanswered question in galaxy evolution: How do relatively isolated, low-mass systems such as dwarf galaxies sustain star formation for extended periods of time?

    Due to its relative proximity to Earth UGC 8201 is an excellent object for research and provides an opportunity to improve our understanding of how dwarf galaxies evolve and grow.

    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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  • richardmitnick 12:55 pm on March 17, 2015 Permalink | Reply
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    From Hubble for St Partick’s Day: “Hubble Zooms in on a Space Oddity” Story from 2011 

    NASA Hubble Telescope

    Hubble

    January 10, 2011

    2

    One of the strangest space objects ever seen is being scrutinized by the penetrating vision of NASA’s Hubble Space Telescope. A mysterious, glowing green blob of gas is floating in space near a spiral galaxy. Hubble uncovered delicate filaments of gas and a pocket of young star clusters in the giant object, which is the size of our Milky Way galaxy.

    The Hubble revelations are the latest finds in an ongoing probe of Hanny’s Voorwerp (Hanny’s Object in Dutch), named for Hanny van Arkel, the Dutch teacher who discovered the ghostly structure in 2007 while participating in the online Galaxy Zoo project. Galaxy Zoo enlists the public to help classify more than a million galaxies catalogued in the Sloan Digital Sky Survey.

    SDSS Telescope
    SDSS telescope at Apache Point, NM, USA

    The project has expanded to include the Hubble Zoo, in which the public is asked to assess tens of thousands of galaxies in deep imagery from the Hubble Space Telescope.

    In the sharpest view yet of Hanny’s Voorwerp, Hubble’s Wide Field Camera 3 {WFC3] and Advanced Camera for Surveys [ACS] have uncovered star birth in a region of the green object that faces the spiral galaxy IC 2497, located about 650 million light-years from Earth.

    NASA Hubble WFC3
    WFC3

    NASA Hubble ACS
    ACS

    Radio observations have shown an outflow of gas arising from the galaxy’s core. The new Hubble images reveal that the galaxy’s gas is interacting with a small region of Hanny’s Voorwerp, which is collapsing and forming stars. The youngest stars are a couple of million years old.

    “The star clusters are localized, confined to an area that is over a few thousand light-years wide,” explains astronomer William Keel of the University of Alabama in Tuscaloosa, leader of the Hubble study. “The region may have been churning out stars for several million years. They are so dim that they have previously been lost in the brilliant light of the surrounding gas.”

    Recent X-ray observations have revealed why Hanny’s Voorwerp caught the eye of astronomers. The galaxy’s rambunctious core produced a quasar, a powerful light beacon powered by a black hole. The quasar shot a broad beam of light in Hanny’s Voorwerp’s direction, illuminating the gas cloud and making it a space oddity. Its bright green color is from glowing oxygen.

    “We just missed catching the quasar, because it turned off no more than 200,000 years ago, so what we’re seeing is the afterglow from the quasar,” Keel says. “This implies that it might flicker on and off, which is typical of quasars, but we’ve never seen such a dramatic change happen so rapidly.”

    The quasar’s outburst also may have cast a shadow on the blob. This feature gives the illusion of a gaping hole about 20,000 light-years wide in Hanny’s Voorwerp. Hubble reveals sharp edges around the apparent opening, suggesting that an object close to the quasar may have blocked some of the light and projected a shadow on Hanny’s Voorwerp. This phenomenon is similar to a fly on a movie projector lens casting a shadow on a movie screen.

    Radio studies have revealed that Hanny’s Voorwerp is not just an island gas cloud floating in space. The glowing blob is part of a long, twisting rope of gas, or tidal tail, about 300,000 light-years long that wraps around the galaxy. The only optically visible part of the rope is Hanny’s Voorwerp. The illuminated object is so huge that it stretches from 44,000 light-years to 136,000 light-years from the galaxy’s core.

    The quasar, the outflow of gas that instigated the star birth, and the long, gaseous tidal tail point to a rough life for IC 2497.

    “The evidence suggests that IC 2497 may have merged with another galaxy about a billion years ago,” Keel explains. “The Hubble images show in exquisite detail that the spiral arms are twisted, so the galaxy hasn’t completely settled down.”

    In Keel’s scenario, the merger expelled the long streamer of gas from the galaxy and funneled gas and stars into the center, which fed the black hole. The engorged black hole then powered the quasar, which launched two cones of light. One light beam illuminated part of the tidal tail, now called Hanny’s Voorwerp.

    About a million years ago, shock waves produced glowing gas near the galaxy’s core and blasted it outward. The glowing gas is seen only in Hubble images and spectra, Keel says. The outburst may have triggered star formation in Hanny’s Voorwerp. Less than 200,000 years ago, the quasar dropped in brightness by 100 times or more, leaving an ordinary-looking core.

    New images of the galaxy’s dusty core from Hubble’s Space Telescope Imaging Spectrograph show an expanding bubble of gas blown out of one side of the core, perhaps evidence of the sputtering quasar’s final gasps. The expanding ring of gas is still too small for ground-based telescopes to detect.

    “This quasar may have been active for a few million years, which perhaps indicates that quasars blink on and off on timescales of millions of years, not the 100 million years that theory had suggested,” Keel says. He added that the quasar could light up again if more material is dumped around the black hole.

    Keel [presented] his results on Jan. 10, 2011, at the American Astronomical Society meeting in Seattle, Wash.

    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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  • richardmitnick 10:58 am on March 12, 2015 Permalink | Reply
    Tags: , , NASA/ESA Hubble   

    From Hubble: “NASA’s Hubble Observations Suggest Underground Ocean on Jupiter’s Largest Moon” 

    NASA Hubble Telescope

    Hubble

    March 12, 2015
    Ann Jenkins / Ray Villard
    Space Telescope Science Institute, Baltimore, Md.
    410-338-4488 / 410-338-4514
    jenkins@stsci.edu / villard@stsci.edu

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

    Joachim Saur
    University of Cologne, Cologne, Germany
    jsaur@uni-koein.de

    1

    2

    NASA’s Hubble Space Telescope has the best evidence yet for an underground saltwater ocean on Ganymede, Jupiter’s largest moon. The subterranean ocean is thought to have more water than all the water on Earth’s surface.

    Identifying liquid water is crucial in the search for habitable worlds beyond Earth and for the search for life as we know it.

    “This discovery marks a significant milestone, highlighting what only Hubble can accomplish,” said John Grunsfeld, assistant administrator of NASA’s Science Mission Directorate at NASA Headquarters, Washington, D.C. “In its 25 years in orbit, Hubble has made many scientific discoveries in our own solar system. A deep ocean under the icy crust of Ganymede opens up further exciting possibilities for life beyond Earth.”

    Ganymede is the largest moon in our solar system and the only moon with its own magnetic field. The magnetic field causes aurorae, which are ribbons of glowing, hot electrified gas, in regions circling the north and south poles of the moon. Because Ganymede is close to Jupiter, it is also embedded in Jupiter’s magnetic field. When Jupiter’s magnetic field changes, the aurorae on Ganymede also change, “rocking” back and forth.

    By watching the rocking motion of the two aurorae, scientists were able to determine that a large amount of saltwater exists beneath Ganymede’s crust, affecting its magnetic field.

    A team of scientists led by Joachim Saur of the University of Cologne in Germany came up with the idea of using Hubble to learn more about the inside of the moon.

    “I was always brainstorming how we could use a telescope in other ways,” said Saur. “Is there a way you could use a telescope to look inside a planetary body? Then I thought, the aurorae! Because aurorae are controlled by the magnetic field, if you observe the aurorae in an appropriate way, you learn something about the magnetic field. If you know the magnetic field, then you know something about the moon’s interior.”

    If a saltwater ocean were present, Jupiter’s magnetic field would create a secondary magnetic field in the ocean that would counter Jupiter’s field. This “magnetic friction” would suppress the rocking of the aurorae. This ocean fights Jupiter’s magnetic field so strongly that it reduces the rocking of the aurorae to 2 degrees, instead of 6 degrees if the ocean were not present.

    Scientists estimate the ocean is 60 miles (100 kilometers) thick — 10 times deeper than Earth’s oceans — and is buried under a 95-mile (150-kilometer) crust of mostly ice.

    Scientists first suspected an ocean in Ganymede in the 1970s, based on models of the large moon. NASA’s Galileo mission measured Ganymede’s magnetic field in 2002, providing the first evidence supporting those suspicions.

    NASA Galileo
    NASA/Galileo

    The Galileo spacecraft took brief “snapshot” measurements of the magnetic field in 20-minute intervals, but its observations were too brief to distinctly catch the cyclical rocking of the ocean’s secondary magnetic field.

    The new observations were done in ultraviolet light and could only be accomplished with a space telescope high above Earth’s atmosphere, which blocks most ultraviolet light.

    The team’s results will be published online in the Journal of Geophysical Research: Space Physics on March 12.

    NASA’s Hubble Space Telescope is celebrating 25 years of groundbreaking science on April 24. It has transformed our understanding of our solar system and beyond, and helped us find our place among the stars.

    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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