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  • richardmitnick 4:34 am on October 30, 2014 Permalink | Reply
    Tags: , , Astronomy, , , ,   

    From astrobio.net: “Planetary Atmospheres a Key to Assessing Possibilities for Life” 

    Astrobiology Magazine

    Astrobiology Magazine

    Oct 30, 2014
    No Writer Credit

    A planetary atmosphere is a delicate thing. On Earth, we are familiar with the ozone hole — a tear in our upper atmosphere caused by human-created chemicals that thin away the ozone. Threats to an atmosphere, however, can also come from natural causes.

    ear
    Earth’s atmosphere likely changed from a helium-heavy one to the nitrogen and oxygen mix we see today. Credit: NASA

    If a big enough asteroid smacks into a planet, it can strip the atmosphere away. Radiation from a star can also make an atmosphere balloon, causing its lighter elements to escape into space.

    Understanding how permanent an atmosphere is, where it came from, and most importantly what it is made of are key to understanding if a planet outside our solar system is habitable for life. Our instruments aren’t yet sophisticated enough to look at atmospheres surrounding Earth-sized planets, but astronomers are starting to gather data on larger worlds to do comparative studies.

    One such example was recently accepted in the journal Astrophysical Journal and is available now in a preprint version on Arxiv. The astronomers created models of planetary formation and then simulated atmospheric stripping, the process where a young star’s radiation can push lighter elements out into space.

    Next, the team compared their findings to data gathered from NASA’s planet-hunting Kepler Space Telescope. The researchers predict that the atmospheric mass of the planets Kepler found is, in some cases, far greater than the thin veneer of air covering Earth.

    NASA Kepler Telescope
    NASA/Kepler

    Co-author Christoph Mordasini, who studies planet and star formation at the Max Planck Institute for Astronomy in Heidelberg, Germany, cautioned there is likely an observational bias with the Kepler data.

    “Kepler systems are so compact, with the planets closer to their star than in our solar system,” said Mordasini.

    Astronomers are still trying to understand why.

    “Maybe some of these objects formed early in their system’s history, in the presence of lots of gas and dust,” he said. “This would have made their atmospheres relatively massive compared to Earth. Our planet probably only formed when the gas was already gone, so it could not form a similar atmosphere.”

    Blowing gas away

    Planetary systems come to be in a cloud of gas and dust, the theory goes. If enough mass gathers in a part of the cloud, that section collapses and creates a star surrounded by a thin disk. When the star ignites, its radiative force will gradually clear the area around it of any debris.

    Over just a few million years, the hydrogen and helium in the disk surrounding the star partially spirals onto the star, while the rest gets pushed farther and farther out into space. Proto-Earth likely had a hydrogen-rich atmosphere at this stage, but over time (with processes such as vulcanism, comet impacts, and biological activity) its atmosphere gradually changed to the nitrogen and oxygen composition we see today.

    Kepler’s data has showed other differences from our own solar system. In our own solar system, there is a vast size difference between Earth and the next-biggest planet, Neptune, which has a radius almost four times that of Earth’s. This means there’s a big dividing line when it comes to size between terrestrial planets and gas giants in our solar system.

    venus
    This global view of the surface of Venus is centered at 180 degrees east longitude. Magellan synthetic aperture radar mosaics from the first cycle of Magellan mapping are mapped onto a computer-simulated globe to create this image. Data gaps are filled with Pioneer Venus Orbiter data, or a constant mid-range value. Simulated color is used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. Credit: NASA/JPL

    In Kepler surveys (as well as surveys from other planet-hunting telescopes), scientists have found more of a gradient. There are other planetary systems out there with planets in between Earth’s and Neptune’s sizes, which are sometimes called “super-Earths” or “mini-Neptunes.” Whether planets of this size are habitable is up for debate.

    “The gap between the Earth’s and Uranus’ or Neptune’s size, and also in their composition, doesn’t exist in extrasolar planets. So, what we see in the Solar System is not the rule,” Mordasini said.

    The planets that Kepler has picked up, however, tend to be massive and closer to their star, and are therefore easier to detect. They pass more frequently across the face of their parent star, making them more easily spotted from Earth.

    The size implies that they managed to grab their disk’s primordial hydrogen and helium atmosphere before it got blown away. Hydrogen and helium are light elements, so a star’s radiation would puff up the hydrogen and helium atmosphere far more than what we see on Earth, with its heavier elements.

    What does this mean? The team predicts that in some cases, when astronomers measure the radius of a planet, that measurement also includes a bulky atmosphere. In other words, the planet underneath could be a lot smaller than what Kepler’s measurements could indicate.

    This process assumes that the planet has an iron core and silica mantle, just like the Earth, but orbits its parent star about 10 times closer than we do ours. If the atmosphere is more massive — even 1 percent of the planet’s mass is many thousands of times more massive than Earth’s — it creates more pressure on the surface.

    “It depends, but you can imagine this pressure is comparable to the deepest parts of the Earth’s ocean. Additionally, these atmospheres can be isolating and insulating for heat, so it’s also very hot on the surface,” Mordasini said.

    High temperatures on Earth are known to destroy amino acids, the building blocks of carbon-based life.

    Delicate atmosphere

    The atmosphere may be more massive, but it is also delicate. It wouldn’t take too much of a push to send hydrogen, the lightest element, away from the planet and into space.

    k69
    A habitable zone planet, Kepler-69c, in an artist’s impression. The world is probably an inhospitable “super-Venus,” but then again, it might be habitable, depending on the character of its atmosphere. Credit: NASA Ames/JPL-Caltech

    Young stars like the Sun in its youth are especially active in x-rays and ultraviolet radiation. When these forms of light hit a planetary atmosphere, they tend to heat it up. Since heating expands gases, the atmosphere grows. An atmosphere that flows beyond certain heights can get so high that part of it gets “unbounded” from the planet’s gravity and escapes into space.

    In our own solar system, for example, Mars likely lost its hydrogen to space over time while a heavier kind of hydrogen (called deuterium) remained behind. A new NASA orbiting spacecraft called Mars Atmosphere and Volatile Evolution (MAVEN) has just arrived at the Red Planet to study more about atmospheric escape today and researchers will to try to extrapolate that knowledge to space.

    NASA MAVEN
    NASA/MAVEN

    By contrast, the planet Venus is an example of having an exceptionally persistent atmosphere. The mostly carbon dioxide atmosphere is so thick today that the planet is completely shrouded in clouds. Underneath the atmosphere is a hellish environment, one in which the spacecraft that have made it there have only survived a few minutes in the 864 º Fahrenheit (462 º Celsius) heat on the surface. It is widely presumed that atmospheres like that of Venus would be too hot for carbon-based life.

    Why Venus, Mars and Earth are so different in their atmospheric composition and history is among the questions puzzling astronomers today. Understanding atmospheric escape on each of these worlds will be helpful, scientists say.

    “How strong atmospheric escape is depends on fundamental properties such as mass or planetary orbit,” Mordasini said. “We found out for giant planets like Jupiter, the operation is typically not as strong.”

    Future work of the team includes considering atmospheres that are not made of hydrogen or helium, which could bring researchers a step closer to understanding how different types of elements work on planets. Eventually, this could feed into models predicting habitability.

    See the full article here.

    NASA

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  • richardmitnick 5:29 pm on October 29, 2014 Permalink | Reply
    Tags: Astronomy, , , , ,   

    From SKA: “Australian Square Kilometre Array telescope takes shape in WA outback” 

    SKA Square Kilometer Array

    SKA

    13 Oct 2014
    Gian De Poloni

    A project to build one of the world’s most powerful radio astronomy telescopes is taking shape in Western Australia’s outback.

    The $160 million Australian Square Kilometre Array Pathfinder [ASKAP] is being built in a radio quiet area of WA’s Murchison region, about a four-hour drive from the port city of Geraldton.

    three
    Photo: Three ASKAP telescopes are trained towards the sky east of Geraldton. (Alex Cherney)

    The project has seen the installation of 36 huge antenna dishes on Boolardy Station, which will eventually work together to survey large areas of sky to help scientists understand how galaxies have formed and evolved.

    CSIRO scientist Lisa Harvey-Smith said although only six of the dishes were active, the images that had been taken so far were remarkable.

    “The latest picture we’ve taken has almost 2000 galaxies in it, which is incredible,” she said.

    “It’s kind of a wide field image of the sky.

    “Once we’ve got 36 telescopes, we’ll be able to do a huge survey of the entire night’s sky and see millions of new galaxies, black holes and things in the very distant universe that no one’s ever seen before.”

    She said the question of what exactly the telescope will be able to see in distant space was a complete mystery.

    “The discovery potential of this telescope is quite amazing,” she said.

    “Even now, we’ve been able to look at galaxies that are actually older than our Earth – which is a pretty incredible thing – and look into the distant universe to search for galaxies that were actually around billions of years ago and may not exist anymore.”

    Dr Harvey-Smith said the giant dishes were picking up radio waves being emitted from objects in space.

    “Our eyes can’t see radio waves, so the data that we get is just boring ones and zeros, but we actually use clever computer algorithms and a super computer that’s based in Perth to make the images into real optical type images that we can see,” she said.

    Telescope will view area 200 time size of moon

    Project director Antony Schinckel said images produced so far were stunning.

    “The thing about ASKAP is it’s a completely new type of telescope – it’s never been built before – so a lot of this very early work is simply understanding exactly how to use it,” he said.

    “Many of our staff said ‘look, it’s not worth trying to do much with just the six dishes because we won’t be able to see much’, but they’ve been completely shown to be wrong.

    “Trying to predict ahead to what we’re going to see with 36 at the full capability is really hard but we’ll be able to very quickly map really big areas of the sky and by really big, I mean in a single snapshot we’ll be able to see an area around about 200 times the size of the full moon.

    “There are still huge holes in our knowledge of how our universe evolved, where galaxies come from, how planets form and we expect ASKAP will be able to really help us answer a lot of that.”

    Dr Schinckel estimated it would cost about $10 million a year to keep the project going.

    “We’ve had good support from the Government over the last few years and we believe the Government does see the positive impacts of these sorts of projects,” he said.

    “There’s the pure science side, there’s the very tight international collaboration aspect, there’s the technology spin off, there’s training of engineers and scientists who may or may not stay on in astronomy but may go on to work in other fields.”

    ASKAP is viewed as a precursor to the future $1.9 billion Square Kilometre Array, which will be built in both the Murchison and South Africa in 2018, with input in design and funding coming from 11 countries.

    The SKA is expected to be the largest and most capable radio telescope.

    what
    Photo: This wide shot image taken from the ASKAP telescope over 12 hours shows distant galaxies. (Supplied: CSIRO)

    telescope
    ASKAP telescope image Photo: This wide shot image taken from the ASKAP telescope over 12 hours shows distant galaxies. (Supplied: CSIRO)

    Murchison ideal location for project

    Dr Harvey-Smith said the isolation of the Murchison region made it the perfect place for the project.

    “If you could imagine trying to listen for a mouse under your floorboards hearing tiny scratching noises, you don’t want to be playing the radio very loudly in the background,” she said.

    “It’s the same type of thing with the radio telescopes.

    “We’re looking for tiny, tiny signals incredibly week from galaxies billions of light years away.
    Under a brilliant night sky, ASKAP telescopes are pointed to the night stars Photo: Raw data from the ASKAP telescopes totals about 100 terabytes per second. (Alex Cherney)

    “They’re so weak we have to amplify them millions of times with specialist electronic equipment.”

    Dr Schinckel said the communications infrastructure in place to support the telescope was unfathomable.

    “The raw data rate we get from the telescopes is about 100 terabytes per second,” he said.

    “To put that in context, that’s about the entire traffic of the internet all around the world in one second.

    “Luckily the super computers we have on site can very quickly reduce the data back to a more manageable volume of around about 10 gigabytes per second.

    “The sheer volume of that and the speed of which that raw data comes in is truly astounding.”

    Dr Harvey Smith said she could control the telescope from the comfort of her lounge room.

    “As one of the research scientists, I can access the telescope from Sydney – from my house, on my laptop,” she said.

    “We just send signals through the internet and tell the telescope what to do.

    “It’s pretty amazing that we can have a giant international scientific facility with very few people actually out there on the site.”

    It is hoped the entire network of dishes will be fully operational by March 2016.

    See the full article here.

    SKA Banner

    About SKA

    The Square Kilometre Array will be the world’s largest and most sensitive radio telescope. The total collecting area will be approximately one square kilometre giving 50 times the sensitivity, and 10 000 times the survey speed, of the best current-day telescopes. The SKA will be built in Southern Africa and in Australia. Thousands of receptors will extend to distances of 3 000 km from the central regions. The SKA will address fundamental unanswered questions about our Universe including how the first stars and galaxies formed after the Big Bang, how dark energy is accelerating the expansion of the Universe, the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. Construction of phase one of the SKA is scheduled to start in 2016. The SKA Organisation, with its headquarters at Jodrell Bank Observatory, near Manchester, UK, was established in December 2011 as a not-for-profit company in order to formalise relationships between the international partners and centralise the leadership of the project.

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  • richardmitnick 4:52 pm on October 29, 2014 Permalink | Reply
    Tags: Astronomy, , , , , Redshift   

    From Frontier Fields: “Light Detectives: Using Color to Estimate Distance” 

    Frontier Fields
    Frontier Fields

    October 28, 2014
    Dr. Brandon Lawton

    Distances are notoriously difficult to measure in astronomy. Astronomers use many methods for estimating distances, but the farther away an object is, the more uncertain the results. Cosmological distances, distances on the largest scales of our universe, are the most difficult to estimate. To measure the distances to the farthest galaxies, those gravitationally lensed by massive foreground galaxy clusters, astronomers really have their work cut out for them.

    If a massive stellar explosion, known as a supernova, happens to go off in a galaxy and we catch it, then we can use the “standard candle” method of computing the distance to the galaxy. Supernovae are expected to be discovered in the Frontier Fields, but not at the numbers that will help us find distances to most of the galaxies in the images. Without these standard candles, astronomers must use other means to estimate distances.

    A Spectrum is Worth a Thousand Pictures

    One of the more accurate methods for measuring the distance to a distant galaxy involves obtaining a spectrum of the galaxy. Getting a galaxy’s spectrum basically means taking the light from that galaxy and breaking it up into its component colors, much like a prism breaks up white light into the rainbow of visible colors. By comparing the brightness of light at each component color, a spectrum can give us a wealth of information. This can include detailed information about a galaxy’s composition, temperature, and how fast it is moving relative to us. Because the universe is expanding, we observe most galaxies, and all distant galaxies, to be moving away from us.

    When looking at a distant galaxy’s spectrum, the expansion of the universe causes the component colors in the spectrum to be stretched to longer wavelengths. For visible light, red has the longest wavelengths, which leads to the term ‘redshift’. This cosmological redshift can be accurately measured from a spectrum. Astronomers then use mathematical models of the expansion rate of our universe to convert the measured redshift into an estimate of distance. Larger values of redshift correspond to larger distances.

    This video, developed by the Office of Public Outreach at the Space Telescope Science Institute, gives a demonstration of how light is redshifted as it travels through the expanding universe. Here, the lightbulb stands in place of a galaxy. As the universe expands, it stretches the light traveling through the universe, increasing the light’s wavelength. As the wavelength increases, it becomes more red. Light traveling longer distances through the universe will be stretched/reddened more than light traveling short distances. This is why astronomers use instruments sensitive to redder light, including infrared light, when they attempt to observe the light from very distant galaxies. Watch this video on Youtube.

    Larger redshifts not only correspond to larger distances, but they also correspond to earlier times in our universe’s history. This is because light takes time to travel to us from these distant galaxies. The more distant the galaxy, the longer the light has been traveling before we intercept it with sensitive telescopes, like Hubble.

    Assuming typical contemporary mathematical models, the universe is about 13.8 billion years old. Galaxies at a redshift of 1 are seen as they existed when the universe was about 6 billion years old. Galaxies at a redshift of 3 are seen as they existed when the universe was about 2 billion years old. Galaxies at a redshift of 6 are seen as they existed when the universe was about 1 billion years old. Galaxies at a redshift of 10 are seen as they existed when the universe was only about 500 million years old.

    It is notoriously difficult to obtain a spectrum of a very distant galaxy. They are very faint, and an accurate spectrum relies on obtaining a lot of light. One is, after all, taking what little light you get and breaking it up further into the component colors, meaning that you start with little light and get out even less light at each component color. Getting enough light to take an accurate spectrum of a distant galaxy requires very lengthy observations with sensitive telescopes. This is not always feasible.

    Redshifts measured via spectra are called spectroscopic redshifts. Many of the nearer galaxies in Abell 2744 have measured spectroscopic redshifts. There will likely be many follow-up observations from ground- and space-based observatories to obtain spectra of many of the fainter and more distant galaxies in the Frontier Fields. So stay tuned!
    I Can’t Obtain a Spectrum! What to do?

    If you do not have a spectrum, are there other ways to estimate the redshift and distance to a galaxy? Yes! Just take a look at the galaxy’s colors.

    All Hubble images are taken with filters. Blue filters allow Hubble’s instruments to capture only blue light, red filters allow Hubble’s instruments to capture only red light, and so on. By comparing a galaxy’s brightnesses in these different colors, astronomers can estimate the distance to the galaxy. The redder the color, the more likely the galaxy is to be redshifted, and thus, farther away.

    This technique of using color to estimate redshift is called photometric redshift. The following two primary methods are used for estimating a photometric redshift:

    compare the colors of your high-redshift galaxy candidate to a set of typical galaxy color templates at various redshifts, or
    compare the colors of your high-redshift galaxy candidate to a set of galaxies with measured spectroscopic redshifts and, utilizing specialized software, compute the most likely redshift for your galaxy.

    In the first case, the photometric redshift comes from the best match between the observed high-redshift candidate colors and the colors of the template galaxies. The template galaxy colors stem from observations of galaxies that tend to be relatively close but are then mathematically reddened over a range of redshift values.

    In the second case, astronomers use a set of observed galaxies whose redshifts have been measured spectroscopically, as explained in the prior section. This set contains galaxies at various redshifts. They then use machine-learning algorithms to compare the colors of this set of galaxies with the colors of the target high-redshift galaxy candidate. The software selects the most likely redshift.

    Whichever method is used, astronomers are careful to give confidence levels in their calculations. For the computation of photometric redshift, there is typically an uncertainty of around a few percent for high-quality data. In addition, there is the lingering issue of whether the high-redshift galaxy candidate is truly redshifted, or if it is a nearer galaxy that is intrinsically redder. It is not uncommon to read results where astronomers find a galaxy with a probable high photometric redshift and a less probable low photometric redshift, or vice versa.

    shif
    Credit: Adapted from Adi Zitrin, et al., 2014. Shown is a high-redshift galaxy candidate in Hubble’s observations of Abel 2744, discovered using filters. Dark regions represent light in these images. Notice how the galaxy drops out of the image in the bluest filters. This is a hint that the galaxy may be significantly redshifted.

    Many of the first results for the Frontier Fields utilize photometric redshifts. In the absence of spectra, photometric redshifts are the next best thing to obtaining estimates of distances for large samples of galaxies. They are readily computed from the current Frontier Fields data.

    See the full article, with video, here.

    Frontier Fields draws on the power of massive clusters of galaxies to unleash the full potential of the Hubble Space Telescope. The gravity of these clusters warps and magnifies the faint light of the distant galaxies behind them. Hubble captures the boosted light, revealing the farthest galaxies humanity has ever encountered, and giving us a glimpse of the cosmos to be unveiled by the James Webb Space Telescope.

    NASA Hubble Telescope
    Hubble
    NASA James Webb Telescope
    Webb
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  • richardmitnick 4:31 pm on October 29, 2014 Permalink | Reply
    Tags: Astronomy, , ,   

    From Chandra: “NASA’S Chandra Observatory Identifies Impact of Cosmic Chaos on Star Birth” 

    NASA Chandra

    October 27, 2014

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

    Janet Anderson
    Marshall Space Flight Center, Huntsville, Ala.
    256-544-6162
    janet.l.anderson@nasa.gov

    Megan Watzke
    Chandra X-ray Center, Cambridge, Mass.
    617-496-7998
    mwatzke@cfa.harvard.edu

    The same phenomenon that causes a bumpy airplane ride, turbulence, may be the solution to a long-standing mystery about stars’ birth, or the absence of it, according to a new study using data from NASA’s Chandra X-ray Observatory.

    Galaxy clusters are the largest objects in the universe, held together by gravity. These behemoths contain hundreds or thousands of individual galaxies that are immersed in gas with temperatures of millions of degrees.

    This hot gas, which is the heftiest component of the galaxy clusters aside from unseen dark matter, glows brightly in X-ray light detected by Chandra. Over time, the gas in the centers of these clusters should cool enough that stars form at prodigious rates. However, this is not what astronomers have observed in many galaxy clusters.

    “We knew that somehow the gas in clusters is being heated to prevent it cooling and forming stars. The question was exactly how,” said Irina Zhuravleva of Stanford University in Palo Alto, California, who led the study that appears in the latest online issue of the journal Nature. “We think we may have found evidence that the heat is channeled from turbulent motions, which we identify from signatures recorded in X-ray images.”

    Prior studies show supermassive black holes, centered in large galaxies in the middle of galaxy clusters, pump vast quantities of energy around them in powerful jets of energetic particles that create cavities in the hot gas. Chandra, and other X-ray telescopes, have detected these giant cavities before.

    The latest research by Zhuravleva and her colleagues provides new insight into how energy can be transferred from these cavities to the surrounding gas. The interaction of the cavities with the gas may be generating turbulence, or chaotic motion, which then disperses to keep the gas hot for billions of years.

    “Any gas motions from the turbulence will eventually decay, releasing their energy to the gas,” said co-author Eugene Churazov of the Max Planck Institute for Astrophysics in Munich, Germany. “But the gas won’t cool if turbulence is strong enough and generated often enough.”

    The evidence for turbulence comes from Chandra data on two enormous galaxy clusters named Perseus and Virgo. By analyzing extended observation data of each cluster, the team was able to measure fluctuations in the density of the gas. This information allowed them to estimate the amount of turbulence in the gas.

    tgwo
    Chandra observations of the Perseus and Virgo galaxy clusters suggest turbulence may be preventing hot gas there from cooling, addressing a long-standing question of galaxy clusters do not form large numbers of stars. Image Credit: NASA/CXC/Stanford/I. Zhuravleva et al

    “Our work gives us an estimate of how much turbulence is generated in these clusters,” said Alexander Schekochihin of the University of Oxford in the United Kingdom. “From what we’ve determined so far, there’s enough turbulence to balance the cooling of the gas.

    These results support the “feedback” model involving supermassive black holes in the centers of galaxy clusters. Gas cools and falls toward the black hole at an accelerating rate, causing the black hole to increase the output of its jets, which produce cavities and drive the turbulence in the gas. This turbulence eventually dissipates and heats the gas.

    While a merger between two galaxy clusters may also produce turbulence, the researchers think that outbursts from supermassive black holes are the main source of this cosmic commotion in the dense centers of many clusters.

    An interactive image, podcast, and video about these findings are available at:

    http://chandra.si.edu

    For more Chandra images, multimedia and related materials, visit:

    http://www.nasa.gov/chandra

    See the full article here.

    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

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  • richardmitnick 4:20 pm on October 29, 2014 Permalink | Reply
    Tags: asteroid, Astronomy, , , ,   

    From SPACE.com: “NASA’s Asteroid-Capture Mission Won’t Help Astronauts Reach Mars: Scientist” 

    space-dot-com logo

    SPACE.com

    October 29, 2014
    Mike Wall

    NASA’s bold asteroid-capture mission is an expensive distraction that does little to advance the agency’s overarching goal of getting humans to Mars, one prominent researcher argues.

    For the past 18 months, NASA has been working on a plan to drag an entire near-Earth asteroid, or a boulder plucked from a large space rock, into lunar orbit using a robotic probe. The captured asteroid could then be visited by astronauts aboard the agency’s Orion crew capsule, ideally by 2025 at the latest.

    thing
    This artist’s concept shows how an astronaut might take samples from a captured asteroid moved to a stable lunar orbit as part of NASA’s proposed Asteroid Redirect Mission (ARM).
    Credit: NASA

    NASA officials say this “Asteroid Redirect Mission,” or ARM, will help develop the technologies and know-how required to send astronauts to Mars, which the space agency hopes to accomplish by the mid-2030s.

    “The principal reason that ARM makes no sense is that it is a misstep off the path to Mars,” [Richard P] Binzel of MIT told Space.com. “There’s nothing about sending humans to Mars that requires us to capture an asteroid in a baggie. That’s a multibillion-dollar expenditure that has nothing to do with getting humans to Mars.”

    Binzel lays out his reasoning in a commentary piece published online today (Oct. 29) in the journal Nature.

    “Hardware and operations to capture, contain and redirect an asteroid are dead-end elements with no value for long-dura­tion crewed space travel,” he writes. “Conveying to the public that reaching Mars requires patient and diligent progres­sion in capabilities is the honest alternative to distracting them with a one-off costly stunt.”

    And Binzel has some ideas about how to achieve that progression in capabilities. Indeed, he wrote the new essay primarily to get those ideas out rather than to bash ARM, Binzel told Space.com.

    NASA should scrap ARM, Binzel says, and establish a “Grand Challenge Mission” scheme that selects proposals via a competitive process, much like the agency’s New Frontiers program, which sends robotic probes out to explore the solar system for less than $800 million apiece.

    The budget should be similar to that of New Frontiers, he adds, meaning NASA, the White House and Congress would have to agree to commit about $200 million per year to the effort.

    Binzel envisions three sequential asteroid missions in this proposed setup. The first would be a comprehensive survey of near-Earth asteroids, the vast majority of which whiz close to our planet undetected. Such a search would discover many objects that could serve as “stepping stones” to Mars, he says — asteroids that humanity could visit in their native orbits, exploring increasingly farther afield from one mission to the next.

    “Asteroid retrieval gets you one object; a survey will get you thousands, at a fraction of the cost,” Binzel told Space.com. “Knowing that those objects are there is like a gateway toward human exploration and eventual commercialization.”

    The survey would also find many space rocks that could threaten Earth down the road, he added. It would thus help NASA comply with the George E. Brown Jr. Near-Earth Object Survey Act of 2005, which requires the agency to detect at least 90 percent of all potentially dangerous asteroids at least 460 feet (140 meters) wide by 2020. (The act did not appropriate funding for NASA to do this work, however.)

    In Binzel’s vision, the second mission would test asteroid-deflection techology, while the third would try out ways to robotically extract water and other resources from space rocks.

    But everything starts with the comprehensive near-Earth asteroid survey, which many researchers have been advocating for decades as a way to protect the planet. Binzel hopes his essay can help it get off the ground at long last, by getting people in NASA’s human-spaceflight directorate more solidly behind the idea and tipping the balance.

    “My goal here is to bring awareness of how a survey will benefit human spaceflight,” Binzel said. “My point is that a survey should be of great interest to the human exploration side of NASA because it can deliver thousands of accessible destinations that are on the path to Mars.”

    • See the full article here.

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  • richardmitnick 3:45 pm on October 29, 2014 Permalink | Reply
    Tags: , Astronomy, , , ,   

    From ALMA: “Planet-forming Lifeline Discovered in a Binary Star System” 

    ESO ALMA Array
    ALMA

    Wednesday, 29 October 2014

    Anne Dutrey
    Laboratoire d’Astrophysique de Bordeaux
    University Bordeaux/CNRS – France
    Tel: +33 5 57 776140
    Email: Anne.Dutrey@obs.u-bordeaux1.fr

    Emmanuel DiFolco
    Laboratoire d’Astrophysique de Bordeaux
    University Bordeaux/CNRS France
    Tel: +33 5 57 776136
    Email: Emmanuel.Difolco@obs.u-bordeaux1.fr

    Valeria Foncea
    Education and Public Outreach Officer
    Joint ALMA Observatory
    Santiago, Chile
    Tel: +56 2 467 6258
    Cell: +56 9 75871963
    Email: vfoncea@alma.cl

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

    Charles E. Blue
    Public Information Officer
    National Radio Astronomy Observatory
    Charlottesville, Virginia, USA
    Tel: +1 434 296 0314
    Cell: +1 434.242.9559
    E-mail: cblue@nrao.edu

    Masaaki Hiramatsu
    Education and Public Outreach Officer, NAOJ Chile
    Observatory Tokyo, Japan
    Tel: +81 422 34 3630
    E-mail: hiramatsu.masaaki@nao.ac.jp

    For the first time, researchers using ALMA have detected a streamer of gas flowing from a massive outer disc toward the inner reaches of a binary star system. This never-before-seen feature may be responsible for sustaining a second, smaller disc of planet-forming material that otherwise would have disappeared long ago. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. The results are published in the journal Nature on October 30, 2014.

    A research group led by Anne Dutrey from the Laboratory of Astrophysics of Bordeaux, France and CNRS used the Atacama Large Millimeter/submillimeter Array (ALMA) to observe the distribution of dust and gas in a multiple-star system called GG Tau-A [1]. This object is only a few million years old and lies about 450 light-years from Earth in the constellation of Taurus (The Bull).

    Like a wheel in a wheel, GG Tau-A contains a large, outer disc encircling the entire system as well as an inner disc around the main central star. This second inner disc has a mass roughly equivalent to that of Jupiter. Its presence has been an intriguing mystery for astronomers since it is losing material to its central star at a rate that should have depleted it long ago.

    sytar
    Fig. 1: This artist’s impression shows the dust and gas around the double star system GG Tauri-A. Researchers using ALMA have detected gas in the region between two discs in this binary system. This may allow planets to form in the gravitationally perturbed environment of the binary. Half of Sun-like stars are born in binary systems, meaning that these findings will have major consequences for the hunt for exoplanets. Credit: ESO/L. Calçada

    While observing these structures with ALMA, the team made the exciting discovery of gas clumps in the region between the two discs. The new observations suggest that material is being transferred from the outer to the inner disc, creating a sustaining lifeline between the two [2].

    “Material flowing through the cavity was predicted by computer simulations but has not been imaged before. Detecting these clumps indicates that material is moving between the discs, allowing one to feed off the other,” explains Dutrey. “These observations demonstrate that material from the outer disc can sustain the inner disc for a long time. This has major consequences for potential planet formation.”

    Planets are born from the material left over from star birth. This is a slow process, meaning that an enduring disc is a prerequisite for planet formation. If the feeding process into the inner disc now seen with ALMA occurs in other multiple-star systems the findings introduce a vast number of new potential locations to find exoplanets in the future.

    The first phase of exoplanet searches was directed at single-host stars like the Sun [3]. More recently it has been shown that a large fraction of giant planets orbit binary-star systems. Now, researchers have begun to take an even closer look and investigate the possibility of planets orbiting the individual stars of multiple-star systems. The new discovery supports the possible existence of such planets, giving exoplanet discoverers new happy hunting grounds.

    Emmanuel Di Folco, co-author of the paper, concludes: “Almost half the Sun-like stars were born in binary systems. This means that we have found a mechanism to sustain planet formation that applies to a significant number of stars in the Milky Way. Our observations are a big step forward in truly understanding planet formation.”

    Notes

    [1] GG Tau-A is part of a more complex multiple-star system called GG Tauri. Recent observations of GG Tau-A using the VLTI have revealed that one of the stars — GG Tau Ab, the one not surrounded by a disc — is itself a close binary, consisting of GG Tau-Ab1 and GG Tau-Ab2. This introduced a fifth component to the GG Tau system.

    ESO VLT Interferometer
    ESO VLTI

    [2] An earlier result with ALMA showed an example of a single star with material flowing inwards from the outer part of its disc.

    [3] Because orbits in binary stars are more complex and less stable, it was believed that forming planets in these systems would be more challenging than around single stars.

    More Information

    This research was presented in a paper entitled Planet formation in the young, low-mass multiple stellar system GG Tau-A” by A. Dutrey et al., to appear in the journal Nature.

    The team is composed of Anne Dutrey (University Bordeaux/CNRS, France), Emmanuel Di Folco (University Bordeaux/CNRS), Stephane Guilloteau (University Bordeaux/CNRS), Yann Boehler (University of Mexico, Michoacan, Mexico), Jeff Bary (Colgate University, Hamilton, USA), Tracy Beck (Space Telescope Science Institute, Baltimore, USA), Hervé Beust (IPAG, Grenoble, France), Edwige Chapillon (University Bordeaux/IRAM, France), Fredéric Gueth (IRAM, Saint Martin d’Hères, France), Jean-Marc Huré (University Bordeaux/CNRS), Arnaud Pierens (University Bordeaux/CNRS), Vincent Piétu (IRAM), Michal Simon (Stony Brook University, USA) and Ya-Wen Tang (Academia Sinica Institute of Astronomy and Astrophysics, Taipei, Taiwan).

    See the full article here.

    The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Organization for Astronomical Research in the Southern Hemisphere (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan.

    ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

    NRAO Small

    ESO 50

    NAOJ

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  • richardmitnick 5:44 pm on October 28, 2014 Permalink | Reply
    Tags: Astronomy, , , , ,   

    From Dark Energy Detectives: “Across the world and up all night” 

    Dark Energy Icon
    The Dark Energy Survey

    Undated

    For the last week, detectives from the Dark Energy Survey have been coordinating across four continents to bring to light more evidence of how the fabric of spacetime is stretching and evolving.

    In Sussex, England, over 100 detectives met to discuss the current state and the future of the Survey that is conducted at the Blanco telescope, located at Cerro Tololo in Chile. At this semi-annual collaboration meeting (with a new venue each time), we continued to strategize analyses for the many probes of spacetime evolution and dark energy: as I write, several early results are being prepared for publication.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M Blanco telescope, home of the DECam

    At Cerro Tololo, a team of observers operated the Dark Energy Camera (DECam) on the Blanco telescope, as we make our way through the second season of observing for the Survey. Each season goes August through February, during the Chilean summer.

    DECam
    DECam, built at Fermilab

    The Anglo-Australian Telescope at Siding Spring Observatory in Australia is home to the OzDES Survey – long-term project for obtaining highly precise distance measurements of objects discovered by DES, such as supernovae and galaxy clusters. These “follow-up” measurements will be very important evidence in pinning down the culprit for dark energy.

    Anglo Australian Telescope Exterior
    Anglo Australian Telescope Interior
    Anglo Australian Telescope at Siding Spring Observatory

    At Cerro Pachon, just east of Cerro Tololo, another team of two agents began to search for evidence of highly warped space in the distant cosmos, using the Gemini (South) Telescope (@GeminiObs). We spent six nights working to measure highly accurate distances of strong gravitational lensing systems. These systems are galaxies or groups of galaxies that are massive enough to significantly distort the fabric of space-time. Space and time are so warped that the light rays from celestial objects – like galaxies and quasars – behind these massive galaxies become bent. The resulting images in DECam become stretched or even multiplied – just like an optical lens. In future case reports, we’ll expand on this phenomenon in more detail.

    Gemini South telescope
    Gemini South Interior
    Gemini South

    All the while, supercomputers the National Center for Supercomputing Applications (NCSA) are processing the data from DECam each night, turning raw images into refined data – ready for analysis by the science teams.

    image
    The image above doesn’t display any obvious strong lenses, but it is an example of the exquisite lines of evidence that DES continues to accumulate each night.

    Here are positions of some of the galaxies above. What information can you find about them? There are several electronic forensic tools to assist your investigation (for example, http://ned.ipac.caltech.edu/forms/nearposn.html; take care to enter the positions with the correct formatting, as they are below). Tweet your findings to our agents at @darkenergdetec, and we can compare case notes.

    RA: 304.3226d, Dec: -52.7966d

    RA: 304.2665d, Dec: -52.6728d

    RA: 304.0723d, Dec: -52.7044d

    Good night, and keep looking up,

    Det. B. Nord

    Det. M. Murphy [image processing]

    See the full article here.

    Dark Energy Camera

    The Dark Energy Survey (DES) is designed to probe the origin of the accelerating universe and help uncover the nature of dark energy by measuring the 14-billion-year history of cosmic expansion with high precision. More than 120 scientists from 23 institutions in the United States, Spain, the United Kingdom, Brazil, and Germany are working on the project. This collaboration [has built] an extremely sensitive 570-Megapixel digital camera, DECam, and will mount it on the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory high in the Chilean Andes. Starting in Sept. 2012 and continuing for five years, DES will survey a large swath of the southern sky out to vast distances in order to provide new clues to this most fundamental of questions.

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  • richardmitnick 3:18 pm on October 28, 2014 Permalink | Reply
    Tags: Astronomy, , , , ,   

    From Symmetry: “Scientists mull potential gamma-ray study sites” 

    Symmetry

    October 28, 2014
    Kelen Tuttle

    An international panel is working to determine the two locations from which the Cherenkov Telescope Array will observe the gamma-ray sky.

    Cherenkov Telescope Array
    Cherenkov Telescope Array

    Somewhere in the Southern Hemisphere, about 100 state-of-the-art telescopes will dot the otherwise empty landscape for half a kilometer in every direction. Meanwhile, in the Northern Hemisphere, a swath of land a little over a third the size will house about 20 additional telescopes, every one of them pointing toward the heavens each night for a full-sky view of the most energetic—and enigmatic—processes in the universe.

    This is the plan for the Cherenkov Telescope Array Observatory, the world’s largest and most sensitive gamma-ray detector. The first of the two arrays is scheduled to begin taking data in 2016, with the other coming online in by 2020. At that point, CTA’s telescopes will observe gamma rays produced in some of the universe’s most violent events—everything from supernovas to supermassive black holes.

    Yet where exactly the telescopes will be built remains to be seen.

    Scientists representing the 29-country CTA consortium met last week to discuss the next steps toward narrowing down potential sites in the Northern Hemisphere: two in the United States (both in Arizona) and two others in Mexico and the Canary Islands. Although details from that meeting remain confidential, the CTA resource board is expected to begin negotiations with the potential host countries within the next few months. That will be the final step before the board makes its decision, says Rene Ong, co-spokesperson of CTA and a professor of physics and astronomy at UCLA.

    “Whichever site it goes to, it will be very important in that country,” Ong says. “It’s a major facility, and it will bring with it a huge amount of intellectual capital.”

    Site selection for the Southern Hemisphere is a bit further along. Last April, the CTA resource board narrowed down that list to two potential sites: one in Southern Namibia and one in Northern Chile. The board is now in the process of choosing between the sites based on factors including weather, operating costs, existing infrastructure like roads and utilities, and host country contributions. A final decision is expected soon.

    sites
    Artwork by: Sandbox Studio, Chicago

    “The consortium went through an exhaustive 3-year process of examining the potential sites, and all of the sites now being considered will deliver on the science,” says CTA Project Scientist Jim Hinton, a professor of physics and astronomy at the University of Leicester. “We’re happy that we have so many really good potential sites. If we reach an impasse with one, we can still keep moving forward with the others.”

    Scientists do not completely understand how high-energy gamma rays are created. Previous studies suggest that they stream from jets of plasma pouring out of enormous black holes, supernovae and other extreme environments, but the processes that create the rays—as well as the harsh environments where they are produced—remain mysterious.

    To reach its goal of better understanding high-energy gamma rays, CTA needs to select two sites—one in the Northern Hemisphere and one in the Southern Hemisphere—to see the widest possible swath of sky. In addition, the view from the two sites will overlap just enough to allow experimenters to better calibrate their instruments, reducing error and ensuring accurate measurements.

    With 10 times the sensitivity of previous experiments, CTA will fill in the many blank regions in our gamma-ray map of the universe. Gamma-rays with energies up to 100 gigaelectronvolts have already been mapped by the Fermi Gamma-ray Space Telescope and others; CTA will cover energies up to 100,000 gigaelectronvolts. It will survey more of the sky than any previous such experiment and be significantly better at determining the origin of each gamma ray, allowing researchers to finally understand the astrophysical processes that produce these energetic rays.

    NASA Fermi Telescope
    NASA/Fermi

    CTA may also offer insight into dark matter. If a dark matter particle were to naturally decay or interact with its antimatter partner to release a flash of energy, the telescope array could theoretically detect that flash. In fact, CTA is one of very few instruments that could see such flashes with energies above 100 gigaelectronvolts.

    “I’m optimistic that we’ll see something totally new and unexpected,” Ong says. “Obviously I can’t tell you what it will be—otherwise it wouldn’t be unexpected—but history tells us that when you make a big step forward in capability, you tend to see something totally new. And that’s just what we’re doing here.”

    See the full article here.

    Symmetry is a joint Fermilab/SLAC publication.


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  • richardmitnick 2:45 pm on October 28, 2014 Permalink | Reply
    Tags: Astronomy, , , ,   

    From ESO: “Poland to Join the European Southern Observatory” 


    European Southern Observatory

    28 October 2014
    Richard Hook
    ESO Public Information Officer
    Garching bei München, Germany
    Tel: +49 89 3200 6655
    Cell: +49 151 1537 3591
    Email: rhook@eso.org

    Today Professor Lena Kolarska-Bobińska, the Polish Minister of Science and Higher Education, signed an agreement that will lead to the country joining the European Southern Observatory (ESO) — the world’s most productive ground-based observatory. ESO is looking forward to welcoming Poland as a Member State, following subsequent ratification of the accession agreement.

    table

    Poland’s accession agreement was signed today in Warsaw, Poland, by Minister Kolarska-Bobińska and ESO’s Director General Tim de Zeeuw, in the presence of other senior officials from Poland and ESO. Since this agreement means accession to an international treaty, it must now be submitted to the Polish Parliament for ratification [1]. The signing of the agreement followed its unanimous approval by the ESO Council during an extraordinary meeting on 8 October 2014.

    “We’re very excited to have our membership of ESO on the horizon,” says Minister Kolarska-Bobińska. “This will open up many future opportunities for us, and drive Polish industry, science and technology forward. This will be the beginning of a fantastic partnership for European astronomy and will also strengthen our links with Chile, with whom we are already cooperating intensively, for instance, in the mining industry — another field where Chile’s natural conditions are outstanding.”

    The connection between ESO and Poland extends beyond their respective astronomical communities. For example, the most recent ESO Industry Day was hosted in Warsaw in January 2013. This event gave ESO the chance to inform Polish industry about ESO’s current facilities and its future plans, including the construction of the European Extremely Large Telescope (E-ELT).

    “We are looking forward to having Poland as a member of our organisation,” says ESO’s Director General, Tim de Zeeuw. “Poland will bring a strong astronomical community, which will strengthen the expertise across the ESO Member States, for example in the time-series astronomy. Poland will gain access to some of the best telescopes and observatories in the world, including the Very Large Telescope on Paranal, ALMA at Chajnantor and, in the coming decade, also the European Extremely Large Telescope on Armazones which will be a tremendous step forward. Poland can now be part of the E-ELT construction effort.”

    Poland, the homeland of Nicolaus Copernicus, the astronomer who proposed that the Sun and not the Earth is at the centre of the Solar System, has a rich tradition in astronomy extending to the present. “Polish astronomers have contributed greatly to astronomical research in recent years, and with our accession to ESO this will only continue to grow,” says Minister Kolarska-Bobińska.
    Notes

    [1] After ratification of Poland’s membership of ESO, the ESO Member States will be Austria, Belgium, Brazil (pending ratification), the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom.

    See the full article here.

    Visit ESO in Social Media-

    Facebook

    Twitter

    YouTube

    ESO Main

    ESO, European Southern Observatory, builds and operates a suite of the world’s most advanced ground-based astronomical telescopes.

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  • richardmitnick 11:49 am on October 26, 2014 Permalink | Reply
    Tags: Astronomy, , , ,   

    From Chandra: “Chandra Archive Collection: Chandra’s Archives Come to Life” 

    NASA Chandra

    Six new images from Chandra’s vast archive are being released. Each of these images combines X-rays from Chandra with data from other telescopes. These images represent a tiny fraction of data that is now housed in Chandra’s archive over the mission’s 15 years of operation.

    six
    Composite

    xray
    X-rayCredit NASA/CXC/SAO
    Release Date October 21, 2014

    Every year, NASA’s Chandra X-ray Observatory looks at hundreds of objects throughout space to help expand our understanding of the Universe. Ultimately, these data are stored in the Chandra Data Archive, an electronic repository that provides access to these unique X-ray findings for anyone who would like to explore them. With the passing of Chandra’s 15th anniversary in operation on August 26, 1999, the archive continues to grow as each successive year adds to the enormous and invaluable dataset.

    To celebrate Chandra’s decade and a half in space, and to honor October as American Archives Month, a variety of objects have been selected from Chandra’s archive. Each of the new images we have produced combines Chandra data with those from other telescopes. This technique of creating “multiwavelength” images allows scientists and the public to see how X-rays fit with data of other types of light, such as optical, radio, and infrared. As scientists continue to make new discoveries with the telescope, the burgeoning archive will allow us to see the high-energy Universe as only Chandra can.

    ulPSR B1509-58 (upper left)
    Pareidolia is the psychological phenomenon where people see recognizable shapes in clouds, rock formations, or otherwise unrelated objects or data. When Chandra’s image ofPSR B1509-58, a spinning neutron star surrounded by a cloud of energetic particles, was released in 2009, it quickly gained attention because many saw a hand-like structure in the X-ray emission. In this new image of the system, X-rays from Chandra in gold are seen along with infrared data from NASA’s Wide-field Infrared Survey Explorer (WISE) telescope in red, green, and blue. Pareidolia may strike again in this image as some people report seeing a shape of a face in WISE’s infrared data.

    NASA Wise Telescope
    NASA/Wise

    urRCW 38 (upper right)
    A young star cluster about 5,500 light years from Earth, RCW 38 provides astronomers a chance to closely examine many young, rapidly evolving stars at once. In this composite image, X-rays from Chandra are blue, while infrared data from NASA’s Spitzer Space Telescope are orange and additional infrared data from the 2MASS survey appears white. There are many massive stars in RCW 38 that will likely explode as supernovas. Astronomers studying RCW 38 are hoping to better understand this environment as our Sun was likely born into a similar stellar nursery.

    NASA Spitzer Telescope
    NASA/Spitzer

    2MASS Telescope
    2MASS telescope interior
    Mt. Hopkins 2MASS 1.3-Meter telescope

    mlHercules A (middle left):
    Some galaxies have extremely bright cores, suggesting that they contain a supermassive black hole that is pulling in matter at a prodigious rate. Astronomers call these “active galaxies,” and Hercules A is one of them. In visible light (colored red, green and blue, with most objects appearing white), Hercules A looks like a typical elliptical galaxy. In X-ray light, however, Chandra detects a giant cloud of multimillion-degree gas (purple). This gas has been heated by energy generated by the infall of matter into a black hole at the center of Hercules A that is over 1,000 times as massive as the one in the middle of the Milky Way. Radio data (blue) show jets of particles streaming away from the black hole. The jets span a length of almost one million light years.

    mrKes 73 (middle right):
    The supernova remnant Kes 73, located about 28,000 light years away, contains a so-called anomalous X-ray pulsar, or AXP, at its center. Astronomers think that most AXPs are magnetars, which are neutron star with ultra-high magnetic fields. Surrounding the point-like AXP in the middle, Kes 73 has an expanding shell of debris from the supernova explosion that occurred between about 750 and 2100 years ago, as seen from Earth. The Chandra data (blue) reveal clumpy structures along one side of the remnant, and appear to overlap with infrared data (orange). The X-rays partially fill the shell seen in radio emission (red) by the Very Large Array. Data from the Digitized Sky Survey optical telescope (white) show stars in the field-of-view.

    NRAO VLA
    NRAO VLA

    llMrk 573 (lower left):
    Markarian 573 is an active galaxy that has two cones of emission streaming away from the supermassive black hole at its center. Several lines of evidence suggest that a torus, or doughnut of cool gas and dust may block some of the radiation produced by matter falling into supermassive black holes, depending on how the torus is oriented toward Earth. Chandra data of Markarian 573 suggest that its torus may not be completely solid, but rather may be clumpy. This composite image shows overlap between X-rays from Chandra (blue), radio emission from the VLA (purple), and optical data from Hubble (gold).

    NASA Hubble Telescope
    NASA/ESA Hubble

    4736
    NGC 4736 (also known as Messier 94) is a spiral galaxy that is unusual because it has two ring structures. This galaxy is classified as containing a “low ionization nuclear emission region,” or LINER, in its center, which produces radiation from specific elements such as oxygen and nitrogen. Chandra observations (gold) of NGC 4736, seen in this composite image with infrared data from Spitzer (red) and optical data from Hubble and the Sloan Digital Sky Survey (blue), suggest that the X-ray emission comes from a recent burst of star formation. Part of the evidence comes from the large number of point sources near the center of the galaxy, showing that strong star formation has occurred. In other galaxies, evidence points to supermassive black holes being responsible for LINER properties. Chandra’s result on NGC 4736 shows LINERs may represent more than one physical phenomenon.

    Sloan Digital Sky Survey Telescope
    Sloan Digital Sky Survey Telescope

    NASA’s Marshall Space Flight Center in Huntsville, Alabama, manages the Chandra program for NASA’s Science Mission Directorate in Washington, DC. The Smithsonian Astrophysical Observatory in Cambridge, Massachusetts, controls Chandra’s science and flight operations.

    See the full article here.

    NASA’s Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA’s Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra’s science and flight operations from Cambridge, Mass.

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