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  • richardmitnick 2:23 pm on March 1, 2015 Permalink | Reply
    Tags: , Cosmology,   

    From Daily Galaxy: “Our Observed Universe is a Tiny Corner of an Enormous Cosmos –‘Ruled by Dark Energy'” 

    Daily Galaxy
    The Daily Galaxy

    March 01, 2015
    No Writer Credit

    1

    “This new concept is, potentially, as drastic an enlargement of our cosmic perspective as the shift from pre-Copernican ideas to the realization that the Earth is orbiting a typical star on the edge of the Milky Way.” Sir Martin Rees, physicist, Cambridge University, Astronomer Royal of Great Britain.

    Is our universe merely a part of an enormous universe containing diverse regions each with the right amount of the dark energy and each larger than the observed universe, according to Raphael Bousso, Professor of Theoretical Physics, U of California/Berkeley and Leonard Susskind, Felix Bloch Professor of Physics, Stanford University. The two theorize that information can leak from our causal patch into others, allowing our part of the universe to “decohere” into one state or another, resulting in the universe that we observe.

    The many worlds interpretation of quantum mechanics is the idea that all possible alternate histories of the universe actually exist. At every point in time, the universe splits into a multitude of existences in which every possible outcome of each quantum process actually happens.The reason many physicists love the many worlds idea is that it explains away all the strange paradoxes of quantum mechanics.

    Putting the many world interpretation aside for a moment, another strange idea in modern physics is the idea that our universe was born along with a large, possibly infinite, number of other universes. So our cosmos is just one tiny corner of a much larger multiverse.

    Susskind and Bousso have put forward the idea that the multiverse and the many worlds interpretation of quantum mechanics are formally equivalent, but if both quantum mechanics and the multiverse take special forms.

    Let’s take quantum mechanics first. Susskind and Bousso propose that it is possible to verify the predictions of quantum mechanics. In theory, it could be done if an observer could perform an infinite number of experiments and observe the outcome of them all, which is known as the supersymmetric multiverse with vanishing cosmological constant.

    If the universe takes this form, then it is possible to carry out an infinite number of experiments within the causal horizon of each other. At each instant in time, an infinite (or very large) number of experiments take place within the causal horizon of each other. As observers, we are capable of seeing the outcome of any of these experiments but we actually follow only one.

    Bousso and Susskind argue that since the many worlds interpretation is possible only in their supersymmetric multiverse, they must be equivalent. “We argue that the global multiverse is a representation of the many-worlds in a single geometry,” they say, calling this new idea the multiverse interpretation of quantum mechanics.

    But we have now entered the realm of what mathematical physicist Peter Woit of Columbia calls “Not Even Wrong, because the theory lacks is a testable prediction that would help physicists distinguish it experimentally from other theories of the universe. And without this crucial element, the multiverse interpretation of quantum mechanics is little more than philosophy, according to Woit.

    What this new supersymmetric multiverse interpretation does have is a simplicity– it’s neat and elegant that the many worlds and the multiverse are equivalent. Ockham’s Razor is fulfilled and no doubt, many quantum physicists delight in what appears to be an exciting. plausible interpretation of ultimate if currently untestable, reality.

    Ref: arxiv.org/abs/1105.3796: The Multiverse Interpretation of Quantum Mechanics

    The Daily Galaxy via technologyreview.com

    Image credit: hellstormde.deviantart.com

    See the full article here.

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  • richardmitnick 5:19 am on February 25, 2015 Permalink | Reply
    Tags: , , Cosmology, Stephen Hawking   

    From NOVA: “Stephen Hawking Serves Up Scrambled Black Holes” 

    PBS NOVA

    NOVA

    04 Feb 2014
    Greg Kestin

    1
    Out of the firewall and into the frying pan? Credit: Flickr/Pheexies, under a Creative Commons license.

    Toast or spaghetti?

    That’s the question that physicists have been trying to answer for the last year and a half. After agreeing for decades that anything—or anyone—unlucky enough to fall into a black hole would be ripped and stretched into spaghetti-like strands by the overwhelming gravity, theorists are now contending with the possibility that infalling matter is instead incinerated by a “toasty” wall of fire at the black hole’s horizon. Now, Stephen Hawking has proposed a radical solution: nixing one of the most infamous characteristics of a black hole, its event horizon, or point of no return.

    2
    Stephen Hawking

    The original “spaghetti” scenario follows directly from [Albert] Einstein’s theory of general relativity, which describes how gravity stretches the fabric of space and time. A black hole warps that fabric into a bottomless pit; if you get too close, you reach a point of no return called the horizon, where the slope becomes so steep that you can never climb back out. Inside, the gravity gets stronger and stronger until it tears you limb from limb.

    The first hint that there was a flaw in this picture of a black hole came in 1975, when Stephen Hawking came upon a paradox. He realized that, over a very long time, a black hole will “evaporate”—that is, its mass and energy will gradually leak out as radiation, revealing nothing of what the black hole once contained. This was a shocking conclusion because it suggested that black holes destroy information, a fundamental violation of quantum mechanics, which insists that information be conserved.

    How exactly does black hole evaporation imply that information is destroyed? Let’s say you are reading the last copy of “Romeo and Juliet,” and when you get to the end, grief overcomes you (sorry for the spoiler) and you throw the book into a black hole. After the book falls past the horizon, gravity shreds its pages, and finally it is violently compressed into the central point of the black hole. Then you wait as the black hole slowly evaporates by randomly shooting off particles from its glowing edges without any concern for Romeo or Juliet. As the black hole winks out of existence, only these random subatomic particles remain, floating in space. Where did the Montagues and Capulets go? They are lost forever. You could have thrown in “The Cat in The Hat” and the particles left after evaporation would be indistinguishable from the Shakespearian remnants.

    Hawking realized that something had to give. Either quantum mechanics had to change to accommodate information loss, or Einstein’s theory of gravity was flawed.

    Over the past 40 years theorists have battled in the “black hole wars,” trying to resolve this paradox. Two decades ago, most physicists declared a truce, agreeing to consider the inside and the outside of the black hole as separate spaces. If something falls into the black hole, it has gone to another realm, so just stop thinking about it and its fate, they counseled. This argument was largely accepted until July 2012, when UC Santa Barbara physicist Joseph Polchinski and his colleagues realized the paradox was even more puzzling.

    Polchinski began with a similar thought experiment, but instead of Shakespeare, he imagined tossing entangled particles (particles that are quantum mechanically linked) toward a black hole. What happens, he asked, if one particle falls in the black hole and the other flies out into space? This creates a big problem: We can’t think of the two realms (inside and outside of the black hole) separately because they are tied together by the entangled particles.

    Polchinski proposed a new solution that ripped apart Einstein’s idea of a black hole—literally. If there were something to prevent entanglement across the horizon, he thought, then there would be no problem. So he came up with something called a firewall: a wall of radiation at the black hole’s horizon that burns up anything that hits it. This wall is a tear in space-time that nothing can go through.

    Is incineration finally the solution to the black hole information paradox? The father of the paradox, Stephen Hawking, recently put in his two cents (two pages, actually) in a very brief paper in which he argues against not just firewalls, but also event horizons as an ultimate point-of-no-return. This argument relies on quantum fluctuations in space-time that prevent a horizon from existing at a sharp boundary. He instead proposes a temporary “apparent horizon” that stores matter/energy (and information), chaotically scrambles it, and radiates it back out. This means that, as far as quantum mechanics is concerned, information is not lost; it is just extremely garbled. As Polchinski describes it, “It almost sounds like he is replacing the firewall with a chaos-wall!”

    Are you skeptical? If so, you are in good company. Polchinski, for one, is hesitant, saying “It is not clear what [Hawking’s] picture is. There are no calculations.”

    Steve Giddings, a theoretical physicist at the University of California, Santa Barbara, shares in this reluctance:

    “The big question has been how information escapes a black hole, and what that tells us about faster-than-light signaling or a more serious breakdown of spacetime; the effects Hawking describes don’t appear sufficient to address this.”

    Hawking’s new idea will need some flesh on its bones before we can truly embrace it, but if you don’t like spaghetti or toast, at least you have a third option now: scrambled black holes.

    See the full article here.

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

     
  • richardmitnick 4:32 am on February 25, 2015 Permalink | Reply
    Tags: , Cosmology, ,   

    From phys.org: “How can space travel faster than the speed of light?” 

    physdotorg
    phys.org

    Feb 23, 2015
    Vanessa Janek

    1
    Light speed is often spoken of as a cosmic speed limit… but not everything plays by these rules. In fact, space itself can expand faster than a photon could ever hope to travel.

    Cosmologists are intellectual time travelers. Looking back over billions of years, these scientists are able to trace the evolution of our Universe in astonishing detail. 13.8 billion years ago, the Big Bang occurred. Fractions of a second later, the fledgling Universe expanded exponentially during an incredibly brief period of time called inflation. Over the ensuing eons, our cosmos has grown to such an enormous size that we can no longer see the other side of it.

    But how can this be? If light’s velocity marks a cosmic speed limit, how can there possibly be regions of spacetime whose photons are forever out of our reach? And even if there are, how do we know that they exist at all?

    The Expanding Universe

    Like everything else in physics, our Universe strives to exist in the lowest possible energy state possible. But around 10-36 seconds after the Big Bang, inflationary cosmologists believe that the cosmos found itself resting instead at a “false vacuum energy” – a low-point that wasn’t really a low-point. Seeking the true nadir of vacuum energy, over a minute fraction of a moment, the Universe is thought to have ballooned by a factor of 1050.

    Since that time, our Universe has continued to expand, but at a much slower pace. We see evidence of this expansion in the light from distant objects. As photons emitted by a star or galaxy propagate across the Universe, the stretching of space causes them to lose energy. Once the photons reach us, their wavelengths have been redshifted in accordance with the distance they have traveled.

    This is why cosmologists speak of redshift as a function of distance in both space and time. The light from these distant objects has been traveling for so long that, when we finally see it, we are seeing the objects as they were billions of years ago.

    The Hubble Volume

    Redshifted light allows us to see objects like galaxies as they existed in the distant past; but we cannot see all events that occurred in our Universe during its history. Because our cosmos is expanding, the light from some objects is simply too far away for us ever to see.

    The physics of that boundary rely, in part, on a chunk of surrounding spacetime called the Hubble volume. Here on Earth, we define the Hubble volume by measuring something called the Hubble parameter (H0), a value that relates the apparent recession speed of distant objects to their redshift. It was first calculated in 1929, when Edwin Hubble discovered that faraway galaxies appeared to be moving away from us at a rate that was proportional to the redshift of their light.

    Dividing the speed of light by H0, we get the Hubble volume. This spherical bubble encloses a region where all objects move away from a central observer at speeds less than the speed of light. Correspondingly, all objects outside of the Hubble volume move away from the center faster than the speed of light.

    Yes, “faster than the speed of light.” How is this possible?

    2
    Two sources of redshift: Doppler and cosmological expansion; modeled after Koupelis & Kuhn. Bottom: Detectors catch the light that is emitted by a central star. This light is stretched, or redshifted, as space expands in between. Credit: Brews Ohare

    The answer has to do with the difference between special relativity and general relativity. Special relativity requires what is called an “inertial reference frame” – more simply, a backdrop. According to this theory, the speed of light is the same when compared in all inertial reference frames. Whether an observer is sitting still on a park bench on planet Earth or zooming past Neptune in a futuristic high-velocity rocketship, the speed of light is always the same. A photon always travels away from the observer at 300,000,000 meters per second, and he or she will never catch up.

    General relativity, however, describes the fabric of spacetime itself. In this theory, there is no inertial reference frame. Spacetime is not expanding with respect to anything outside of itself, so the the speed of light as a limit on its velocity doesn’t apply. Yes, galaxies outside of our Hubble sphere are receding from us faster than the speed of light. But the galaxies themselves aren’t breaking any cosmic speed limits. To an observer within one of those galaxies, nothing violates special relativity at all. It is the space in between us and those galaxies that is rapidly proliferating and stretching exponentially.

    The Observable Universe

    Now for the next bombshell: The Hubble volume is not the same thing as the observable Universe.

    To understand this, consider that as the Universe gets older, distant light has more time to reach our detectors here on Earth. We can see objects that have accelerated beyond our current Hubble volume because the light we see today was emitted when they were within it.

    Strictly speaking, our observable Universe coincides with something called the particle horizon. The particle horizon marks the distance to the farthest light that we can possibly see at this moment in time – photons that have had enough time to either remain within, or catch up to, our gently expanding Hubble sphere.

    And just what is this distance? A little more than 46 billion light years in every direction – giving our observable Universe a diameter of approximately 93 billion light years, or more than 500 billion trillion miles.

    (A quick note: the particle horizon is not the same thing as the cosmological event horizon. The particle horizon encompasses all the events in the past that we can currently see. The cosmological event horizon, on the other hand, defines a distance within which a future observer will be able to see the then-ancient light our little corner of spacetime is emitting today.

    In other words, the particle horizon deals with the distance to past objects whose ancient light that we can see today; the cosmological event horizon deals with the distance that our present-day light that will be able to travel as faraway regions of the Universe accelerate away from us.)

    3
    Fit of redshift velocities to Hubble’s law. Credit: Brews Ohare

    Dark Energy

    Thanks to the expansion of the Universe, there are regions of the cosmos that we will never see, even if we could wait an infinite amount of time for their light to reach us. But what about those areas just beyond the reaches of our present-day Hubble volume? If that sphere is also expanding, will we ever be able to see those boundary objects?

    This depends on which region is expanding faster – the Hubble volume or the parts of the Universe just outside of it. And the answer to that question depends on two things: 1) whether H0 is increasing or decreasing, and 2) whether the Universe is accelerating or decelerating. These two rates are intimately related, but they are not the same.

    In fact, cosmologists believe that we are actually living at a time when H0 is decreasing; but because of dark energy, the velocity of the Universe’s expansion is increasing.

    That may sound counterintuitive, but as long as H0 decreases at a slower rate than that at which the Universe’s expansion velocity is increasing, the overall movement of galaxies away from us still occurs at an accelerated pace. And at this moment in time, cosmologists believe that the Universe’s expansion will outpace the more modest growth of the Hubble volume.

    4
    The observable universe, more technically known as the particle horizon.

    So even though our Hubble volume is expanding, the influence of dark energy appears to provide a hard limit to the ever-increasing observable Universe.

    Our Earthly Limitations

    Cosmologists seem to have a good handle on deep questions like what our observable Universe will someday look like and how the expansion of the cosmos will change. But ultimately, scientists can only theorize the answers to questions about the future based on their present-day understanding of the Universe. Cosmological timescales are so unimaginably long that it is impossible to say much of anything concrete about how the Universe will behave in the future. Today’s models fit the current data remarkably well, but the truth is that none of us will live long enough to see whether the predictions truly match all of the outcomes.

    Disappointing? Sure. But totally worth the effort to help our puny brains consider such mind-bloggling science – a reality that, as usual, is just plain stranger than fiction.

    See the full article here.

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 6:47 pm on January 8, 2015 Permalink | Reply
    Tags: , , , , , Cosmology   

    From Caltech: “Unusual Light Signal Yields Clues About Elusive Black Hole Merger” 

    Caltech Logo
    Caltech

    01/07/2015
    Ker Than

    The central regions of many glittering galaxies, our own Milky Way included, harbor cores of impenetrable darkness—black holes with masses equivalent to millions, or even billions, of suns. What is more, these supermassive black holes and their host galaxies appear to develop together, or “co-evolve.” Theory predicts that as galaxies collide and merge, growing ever more massive, so too do their dark hearts.

    bh
    Simulation of gravitational lensing by a black hole, which distorts the image of a galaxy in the background


    ESOCast
    Astronomers using ESO’s Very Large Telescope have discovered a gas cloud with several times the mass of the Earth accelerating towards the black hole at the centre of the Milky Way. This is the first time ever that the approach of such a doomed cloud to a supermassive black hole has been observed. This ESOcast explains the new results and includes spectacular simulations of how the cloud will break up over the next few years.
    Credit: ESO.

    ESO VLT Interferometer
    ESO VLT Interior
    ESO/VLT

    Black holes by themselves are impossible to see, but their gravity can pull in surrounding gas to form a swirling band of material called an accretion disk. The spinning particles are accelerated to tremendous speeds and release vast amounts of energy in the form of heat and powerful X-rays and gamma rays. When this process happens to a supermassive black hole, the result is a quasar—an extremely luminous object that outshines all of the stars in its host galaxy and that is visible from across the universe. “Quasars are valuable probes of the evolution of galaxies and their central black holes,” says George Djorgovski, professor of astronomy and director of the Center for Data-Driven Discovery at Caltech.

    In the January 7 issue of the journal Nature, Djorgovski and his collaborators report on an unusual repeating light signal from a distant quasar that they say is most likely the result of two supermassive black holes in the final phases of a merger—something that is predicted from theory but which has never been observed before. The discovery could help shed light on a long-standing conundrum in astrophysics called the “final parsec problem,” which refers to the failure of theoretical models to predict what the final stages of a black hole merger look like or even how long the process might take. “The end stages of the merger of these supermassive black hole systems are very poorly understood,” says the study’s first author, Matthew Graham, a senior computational scientist at Caltech. “The discovery of a system that seems to be at this late stage of its evolution means we now have an observational handle on what is going on.”

    Djorgovski and his team discovered the unusual light signal emanating from quasar PG 1302-102 after analyzing results from the Catalina Real-Time Transient Survey (CRTS), which uses three ground telescopes in the United States and Australia to continuously monitor some 500 million celestial light sources strewn across about 80 percent of the night sky. “There has never been a data set on quasar variability that approaches this scope before,” says Djorgovski, who directs the CRTS. “In the past, scientists who study the variability of quasars might only be able to follow some tens, or at most hundreds, of objects with a limited number of measurements. In this case, we looked at a quarter million quasars and were able to gather a few hundred data points for each one.”

    “Until now, the only known examples of supermassive black holes on their way to a merger have been separated by tens or hundreds of thousands of light years,” says study coauthor Daniel Stern, a scientist at NASA’s Jet Propulsion Laboratory. “At such vast distances, it would take many millions, or even billions, of years for a collision and merger to occur. In contrast, the black holes in PG 1302-102 are, at most, a few hundredths of a light year apart and could merge in about a million years or less.”

    Djorgovski and his team did not set out to find a black hole merger. Rather, they initially embarked on a systematic study of quasar brightness variability in the hopes of finding new clues about their physics. But after screening the data using a pattern-seeking algorithm that Graham developed, the team found 20 quasars that seemed to be emitting periodic optical signals. This was surprising, because the light curves of most quasars are chaotic—a reflection of the random nature by which material from the accretion disk spirals into a black hole. “You just don’t expect to see a periodic signal from a quasar,” Graham says. “When you do, it stands out.”

    Of the 20 periodic quasars that CRTS identified, PG 1302-102 was the best example. It had a strong, clean signal that appeared to repeat every five years or so. “It has a really nice smooth up-and-down signal, similar to a sine wave, and that just hasn’t been seen before in a quasar,” Graham says.

    The team was cautious about jumping to conclusions. “We approached it with skepticism but excitement as well,” says study coauthor Eilat Glikman, an assistant professor of physics at Middlebury College in Vermont. After all, it was possible that the periodicity the scientists were seeing was just a temporary ordered blip in an otherwise chaotic signal. To help rule out this possibility, the scientists pulled in data about the quasar from previous surveys to include in their analysis. After factoring in the historical observations (the scientists had nearly 20 years’ worth of data about quasar PG 1302-102), the repeating signal was, encouragingly, still there.

    The team’s confidence increased further after Glikman analyzed the quasar’s light spectrum. The black holes that scientists believe are powering quasars do not emit light, but the gases swirling around them in the accretion disks are traveling so quickly that they become heated into glowing plasma. “When you look at the emission lines in a spectrum from an object, what you’re really seeing is information about speed—whether something is moving toward you or away from you and how fast. It’s the Doppler effect,” Glikman says. “With quasars, you typically have one emission line, and that line is a symmetric curve. But with this quasar, it was necessary to add a second emission line with a slightly different speed than the first one in order to fit the data. That suggests something else, such as a second black hole, is perturbing this system.”

    Avi Loeb, who chairs the astronomy department at Harvard University, agreed with the team’s assessment that a “tight” supermassive black hole binary is the most likely explanation for the periodic signal they are seeing. “The evidence suggests that the emission originates from a very compact region around the black hole and that the speed of the emitting material in that region is at least a tenth of the speed of light,” says Loeb, who did not participate in the research. “A secondary black hole would be the simplest way to induce a periodic variation in the emission from that region, because a less dense object, such as a star cluster, would be disrupted by the strong gravity of the primary black hole.”

    In addition to providing an unprecedented glimpse into the final stages of a black hole merger, the discovery is also a testament to the power of “big data” science, where the challenge lies not only in collecting high-quality information but also devising ways to mine it for useful information. “We’re basically moving from having a few pictures of the whole sky or repeated observations of tiny patches of the sky to having a movie of the entire sky all the time,” says Sterl Phinney, a professor of theoretical physics at Caltech, who was also not involved in the study. “Many of the objects in the movie will not be doing anything very exciting, but there will also be a lot of interesting ones that we missed before.”

    It is still unclear what physical mechanism is responsible for the quasar’s repeating light signal. One possibility, Graham says, is that the quasar is funneling material from its accretion disk into luminous twin plasma jets that are rotating like beams from a lighthouse. “If the glowing jets are sweeping around in a regular fashion, then we would only see them when they’re pointed directly at us. The end result is a regularly repeating signal,” Graham says.

    Another possibility is that the accretion disk that encircles both black holes is distorted. “If one region is thicker than the rest, then as the warped section travels around the accretion disk, it could be blocking light from the quasar at regular intervals. This would explain the periodicity of the signal that we’re seeing,” Graham says. Yet another possibility is that something is happening to the accretion disk that is causing it to dump material onto the black holes in a regular fashion, resulting in periodic bursts of energy.

    “Even though there are a number of viable physical mechanisms behind the periodicity we’re seeing—either the precessing jet, warped accretion disk or periodic dumping—these are all still fundamentally caused by a close binary system,” Graham says.

    Along with Djorgovski, Graham, Stern, and Glikman, additional authors on the paper, A possible close supermassive black hole binary in a quasar with optical periodicity, include Andrew Drake, a computational scientist and co-principal investigator of the CRTS sky survey at Caltech; Ashish Mahabal, a staff scientist in computational astronomy at Caltech; Ciro Donalek, a computational staff scientist at Caltech; Steve Larson, a senior staff scientist at the University of Arizona; and Eric Christensen, an associate staff scientist at the University of Arizona. Funding for the study was provided by the National Science Foundation.

    See the full article here.

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    The California Institute of Technology (commonly referred to as Caltech) is a private research university located in Pasadena, California, United States. Caltech has six academic divisions with strong emphases on science and engineering. Its 124-acre (50 ha) primary campus is located approximately 11 mi (18 km) northeast of downtown Los Angeles. “The mission of the California Institute of Technology is to expand human knowledge and benefit society through research integrated with education. We investigate the most challenging, fundamental problems in science and technology in a singularly collegial, interdisciplinary atmosphere, while educating outstanding students to become creative members of society.”
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  • richardmitnick 4:52 pm on January 8, 2015 Permalink | Reply
    Tags: , , , Cosmology, ,   

    From Gemini Observatory: “THE GEMINI PLANET IMAGER PRODUCES STUNNING OBSERVATIONS IN ITS FIRST YEAR” 

    NOAO

    Gemini Observatory
    Gemini Observatory

    January 6, 2015
    Media Contacts:

    Peter Michaud
    Public Information and Outreach Manager
    Gemini Observatory, Hilo, HI
    Email: pmichaud”at”gemini.edu
    Cell: (808) 936-6643
    Desk: (808) 974-2510

    Science Contacts:

    Marshall Perrin
    STScI
    Email: mperrin”at”stsci.edu
    Phone: (410) 507-5483

    James R. Graham
    University of California Berkeley
    Email: jrg”at”berkeley.edu
    Cell: (510) 926-9820

    Stunning exoplanet images and spectra from the first year of science operations with the Gemini Planet Imager (GPI) were featured today in a press conference at the 225th meeting of the American Astronomical Society (AAS) in Seattle, Washington. The Gemini Planet Imager GPI is an advanced instrument designed to observe the environments close to bright stars to detect and study Jupiter-like exoplanets (planets around other stars) and see protostellar material (disk, rings) that might be lurking next to the star.

    1
    Figure 1. GPI imaging of the planetary system HR 8799 in K band, showing 3 of the 4 planets. (Planet b is outside the field of view shown here, off to the left.) These data were obtained on November 17, 2013 during the first week of operation of GPI and in relatively challenging weather conditions, but with GPI’s advanced adaptive optics system and coronagraph the planets can still be clearly seen and their spectra measured (see Figure 2). Image credit: Christian Marois (NRC Canada), Patrick Ingraham (Stanford University) and the GPI Team.

    2
    Figure 2. GPI spectroscopy of planets c and d in the HR 8799 system. While earlier work showed that the planets have similar overall brightness and colors, these newly-measured spectra show surprisingly large differences. The spectrum of planet d increases smoothly from 1.9-2.2 microns while planet c’s spectrum shows a sharper kink upwards just beyond 2 microns. These new GPI results indicate that these similar-mass and equal-age planets nonetheless have significant differences in atmospheric properties, for in-stance more open spaces between patchy cloud cover on planet c versus uniform cloud cover on planet d, or perhaps differences in atmospheric chemistry. These data are helping refine and improve a new generation of atmospheric models to explain these effects. Image credit: Patrick Ingraham (Stanford University), Mark Marley (NASA Ames), Didier Saumon (Los Alamos National Laboratory) and the GPI Team.

    Marshall Perrin (Space Telescope Science Institute), one of the instrument’s team leaders, presented a pair of recent and promising results at the press conference. He revealed some of the most detailed images and spectra ever of the multiple planet system HR 8799. His presentation also included never-seen details in the dusty ring of the young star HR 4796A. “GPI’s advanced imaging capabilities have delivered exquisite images and data,” said Perrin. “These improved views are helping us piece together what’s going on around these stars, yet also posing many new questions.”

    The GPI spectra obtained for two of the planetary members of the HR 8799 system presents a challenge for astronomers. GPI team member Patrick Ingraham (Stanford University), lead the paper on HR 8799. Ingraham reports that the shape of the spectra for the two planets differ more profoundly than expected based on their similar colors, indicating significant differences between the companions. “Current atmospheric models of exoplanets cannot fully explain the subtle differences in color that GPI has revealed. We infer that it may be differences in the coverage of the clouds or their composition.” Ingraham adds, “The fact that GPI was able to extract new knowledge from these planets on the first commissioning run in such a short amount of time, and in conditions that it was not even designed to work, is a real testament to how revolutionary GPI will be to the field of exoplanets.”

    Perrin, who is working to understand the dusty ring around the young star HR 4796A, said that the new GPI data present an unprecedented level of detail in studies of the ring’s polarized light. “GPI not only sees the disk more clearly than previous instruments, it can also measure how polarized its light appears, which has proven crucial in under-standing its physical properties.” Specifically, the GPI measurements of the ring show it must be partially opaque, implying it is far denser and more tightly compressed than similar dust found in the outskirts of our own Solar System, which is more diffuse. The ring circling HR 4796A is about twice the diameter of the planetary orbits in our Solar System and its star about twice our Sun’s mass. “These data taken during GPI commissioning show how exquisitely well its polarization mode works for studying disks. Such observations are critical in advancing our understanding of all types and sizes of planetary systems – and ultimately how unique our own solar system might be,” said Perrin.

    3
    Figure 3. GPI imaging polarimetry of the circumstellar disk around HR 4796A, a ring of dust and planetesimals similar in some ways to a scaled up version of the solar system’s Kuiper Belt.

    Kuiper Belt
    Kuiper Belt, for illustration of the discussion

    These GPI observations reveal a complex pattern of variations in brightness and polarization around the HR 4796A disk. The western side (tilted closer to the Earth) appears brighter in polarized light, while in total intensity the eastern side appears slightly brighter, particularly just to the east of the widest apparent separation points of the disk. Reconciling this complex and apparently-contradictory pattern of brighter and darker regions required a major overhaul of our understanding of this circumstellar disk. Image credit: Marshall Perrin (Space Telescope Science Institute), Gaspard Duchene (UC Berkeley), Max Millar-Blanchaer (University of Toronto), and the GPI Team.

    4
    Figure 4. Diagram depicting the GPI team’s revised model for the orientation and composition of the HR 4796A ring. To explain the observed polarization levels, the disk must consist of relatively large (> 5 µm) silicate dust particles, which scatter light most strongly and polarize it more for forward scattering. To explain the relative faintness of the east side in total intensity, the disk must be dense enough to be slightly opaque, comparable to Saturn’s optically thick rings, such that on the near side of the disk our view of its brightly illuminated inner portion is partially obscured. This revised model requires the disk to be much narrower and flatter than expected, and poses a new challenge for theories of disk dynamics to explain. GPI’s high contrast imaging and polarimetry capabilities together were essential for this new synthesis. Image credit: Marshall Perrin (Space Telescope Science Institute).

    During the commissioning phase, the GPI team observed a variety of targets, ranging from asteroids in our solar system, to an old star near its death. Other teams of scientists have been using GPI as well and already astronomers around the world have published eight papers in peer-reviewed journals using GPI data. “This might be the most productive new instrument Gemini has ever had,” said Professor James Graham of the University of California, who leads the GPI science team and who will describe the GPI exoplanet survey in a talk scheduled at the AAS meeting on Thursday, January 8th.

    The Gemini Observatory staff integrated the complex instrument into the telescope’s software and helped to characterize GPI’s performance. “Even though it’s so complicated, GPI now operates almost automatically,” said Gemini’s instrument scientist for GPI Fredrik Rantakyro. “This allows us to start routine science operations.” The instrument is now available to astronomers and their proposals are scheduled to start ob-serving in early 2015. In addition, “shared risk” observations are already underway, starting in November 2014.

    The one thing GPI hasn’t done yet is discovered a new planet. “For the early tests, we concentrated on known planets or disks” said GPI PI Bruce Macintosh. Now that GPI is fully operational, the search for new planets has begun. In addition to observations by astronomers world-wide, the Gemini Planet Imager Exoplanet Survey (GPIES) will look at 600 carefully selected stars over the next few years. GPI ‘sees’ planets through the infrared light they emit when they’re young, so the GPIES team has assembled a list of the youngest and closest stars. So far the team has observed 50 stars, and analysis of the data is ongoing. Discovering a planet requires confirmation observations to distinguish a true planet orbiting the target star from a distant star that happens to sneak into GPI’s field of view – a process that could take years with previous instruments. The GPIES team found one such object in their first survey run, but GPI observations were sensitive enough to almost immediately rule it out. Macintosh said, “With GPI, we can tell almost instantly that something isn’t a planet – rather than months of uncertainty, we can get over our disappointment almost immediately. Now it’s time to find some real planets!”

    About GPI/GPIES

    The Gemini Planet Imager (GPI) instrument was constructed by an international collaboration led by Lawrence Livermore National Laboratory under Gemini’s supervision. The GPI Exoplanet Survey (GPIES) is the core science program to be carried out with it. GPIES is led by Bruce Macintosh, now a professor at Stanford University and James Graham, professor at the University of California at Berkeley and is designed to find young, Jupiter-like exoplanets. They survey will observe 600 young nearby stars in 890 hours over three years. Targets have been carefully selected by team members at Arizona State University, the University of Georgia, and UCLA. The core of the data processing architecture is led by Marshall Perrin of the Space Telescope Science Institute, with the core software originally written by University of Montreal, data management infrastructure from UC Berkeley and Cornell University, and contributions from all the other team institutions. The SETI institute located in California manages GPIES’s communications and public out-reach. Several teams located at the Dunlap Institute, the University of Western Ontario, the University of Chicago, the Lowell Observatory, NASA Ames, the American Museum of Natural History, University of Arizona and the University of California at San Diego and at Santa Cruz also contribute to the survey. The GPI Exoplanet Survey is supported by the NASA Origins Program NNX14AG80, the NSF AAG pro-gram, and grants from other institutions including the University of California Office of the President. Dropbox Inc. has generously provided storage space for the entire survey’s archive.

    See the full article here.

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    Gemini North
    Gemini North, Hawai’i

    Gemini South
    Gemini South, Chile
    AURA Icon

    The Gemini Observatory consists of twin 8.1-meter diameter optical/infrared telescopes located on two of the best observing sites on the planet. From their locations on mountains in Hawai‘i and Chile, Gemini Observatory’s telescopes can collectively access the entire sky.
    Gemini was built and is operated by a partnership of six countries including the United States, Canada, Chile, Australia, Brazil and Argentina. Any astronomer in these countries can apply for time on Gemini, which is allocated in proportion to each partner’s financial stake.

     
  • richardmitnick 4:31 am on January 8, 2015 Permalink | Reply
    Tags: , , , Cosmology, ,   

    From NASA Science: “Hubble: Pillars of Creation are also Pillars of Destruction” 

    NASA Science Science News

    Jan. 7, 2015
    Dr. Tony Phillips

    Although NASA’s Hubble Space Telescope has taken many breathtaking images of the universe, one snapshot stands out from the rest: the iconic view of the so-called “Pillars of Creation.” The jaw-dropping photo, taken in 1995, revealed never-before-seen details of three giant columns of cold gas bathed in the scorching ultraviolet light from a cluster of young, massive stars in a small region of the Eagle Nebula, or M16.

    e
    Overview of some famous sights in the Eagle Nebula

    NASA Hubble Telescope
    Hubble

    In celebration of its upcoming 25th anniversary in April, Hubble has revisited the famous pillars, providing astronomers with a sharper and wider view. Although the original image was dubbed the Pillars of Creation, the new image hints that they are also “pillars of destruction.”

    p
    Astronomers using NASA’s Hubble Space Telescope have assembled a bigger and sharper photograph of the iconic Eagle Nebula’s “Pillars of Creation”. Credit: NASA/ESA/Hubble Heritage Team (STScI/AURA)/J. Hester, P. Scowen (Arizona State U.)

    “I’m impressed by how transitory these structures are,” explains Paul Scowen of Arizona State University in Tempe. “They are actively being ablated away before our very eyes. The ghostly bluish haze around the dense edges of the pillars is material getting heated up and evaporating away into space. We have caught these pillars at a very unique and short-lived moment in their evolution.” Scowen and astronomer Jeff Hester, formerly of Arizona State University, led the original Hubble observations of the Eagle Nebula.


    HUBBLECast 82

    The original 1995 images were taken in visible light. The new image includes near-infrared light as well. The infrared view transforms the pillars into eerie, wispy silhouettes seen against a background of myriad stars. That’s because the infrared light penetrates much of the gas and dust, except for the densest regions of the pillars. Newborn stars can be seen hidden away inside the pillars.

    The infrared image shows that the very ends of the pillars are dense knots of dust and gas. They shadow the gas below them, keeping the gas cool and creating the long, column-like structures. The material in between the pillars has long since been evaporated away by the ionizing radiation from the central star cluster located above the pillars.

    At the top edge of the left-hand pillar, a gaseous fragment has been heated up and is flying away from the structure, underscoring the violent nature of star-forming regions. “These pillars represent a very dynamic, active process,” Scowen said. “The gas is not being passively heated up and gently wafting away into space. The gaseous pillars are actually getting ionized, a process by which electrons are stripped off of atoms, and heated up by radiation from the massive stars. And then they are being eroded by the stars’ strong winds and barrage of charged particles, which are literally sandblasting away the tops of these pillars.”

    When Scowen and Hester used Hubble to make the initial observations of the Eagle Nebula in 1995, astronomers had seen the pillar-like structures in ground-based images, but not in detail. They knew that the physical processes are not unique to the Eagle Nebula because star birth takes place across the universe. But at a distance of just 6,500 light-years, M16 is the most dramatic nearby example – as the team soon realized.

    As Scowen was piecing together the Hubble exposures of the Eagle, he was amazed at what he saw. “I called Jeff Hester on his phone and said, ‘You need to get here now,’” Scowen recalled. “We laid the pictures out on the table, and we were just gushing because of all the incredible detail that we were seeing for the very first time.”

    The first features that jumped out at the team in 1995 were the streamers of gas seemingly floating away from the columns. Astronomers had previously debated what effect nearby massive stars would have on the surrounding gas in stellar nurseries. “There is the only one thing that can light up a neighborhood like this: massive stars kicking out enough horsepower in ultraviolet light to ionize the gas clouds and make them glow,” Scowen said. “Nebulous star-forming regions like M16 are the interstellar neon signs that say, ‘We just made a bunch of massive stars here.’ This was the first time we had directly seen observational evidence that the erosionary process, not only the radiation but the mechanical stripping away of the gas from the columns, was actually being seen.”

    o
    The original 1995 image was beautiful.

    By comparing the 1995 and 2014 pictures, astronomers also noticed a lengthening of a narrow jet-like feature that may have been ejected from a newly forming star. The jet looks like a stream of water from a garden hose. Over the intervening 19 years, this jet has stretched farther into space, across an additional 60 billion miles, at an estimated speed of about 450,000 miles per hour.

    Our sun probably formed in a similar turbulent star-forming region. There is evidence that the forming solar system was seasoned with radioactive shrapnel from a nearby supernova. That means that our sun was formed as part of a cluster that included stars massive enough to produce powerful ionizing radiation, such as is seen in the Eagle Nebula. “That’s the only way the nebula from which the sun was born could have been exposed to a supernova that quickly, in the short period of time that represents, because supernovae only come from massive stars, and those stars only live a few tens of millions of years,” Scowen explained. “What that means is when you look at the environment of the Eagle Nebula or other star-forming regions, you’re looking at exactly the kind of nascent environment that our sun formed in.”

    See the full article here.

    Pillars in Near Infrared from ESO’s VLT
    3

    The 8.2-meter VLT’s ANTU telescope imaged the famous “Pillars of Creation” region and its surroundings in near-infrared using the ISAAC instrument. This enabled astronomers to penetrate the obscuring dust in their search to detect newly formed stars. The near-infrared results showed that 11 of the Pillars’ 73 evaporating gaseous globules (or EGGs) possibly contained stars, and that the tips of the pillars contain stars and nebulosity not seen in the Hubble image.

    ESA Video showing the Pillars in a variety of wavelengths.

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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.

    NASA leads the nation on a great journey of discovery, seeking new knowledge and understanding of our planet Earth, our Sun and solar system, and the universe out to its farthest reaches and back to its earliest moments of existence. NASA’s Science Mission Directorate (SMD) and the nation’s science community use space observatories to conduct scientific studies of the Earth from space to visit and return samples from other bodies in the solar system, and to peer out into our Galaxy and beyond. NASA’s science program seeks answers to profound questions that touch us all:

    This is NASA’s science vision: using the vantage point of space to achieve with the science community and our partners a deep scientific understanding of our planet, other planets and solar system bodies, the interplanetary environment, the Sun and its effects on the solar system, and the universe beyond. In so doing, we lay the intellectual foundation for the robotic and human expeditions of the future while meeting today’s needs for scientific information to address national concerns, such as climate change and space weather. At every step we share the journey of scientific exploration with the public and partner with others to substantially improve science, technology, engineering and mathematics (STEM) education nationwide.

    NASA

     
  • richardmitnick 8:10 pm on January 7, 2015 Permalink | Reply
    Tags: , , , Cosmology,   

    From NOAO: “Smashing Results About Our Nearby Galactic Neighbors” 

    NOAO Banner

    January 5, 2015
    Dr. Katy Garmany
    Deputy Press Officer
    National Optical Astronomy Observatory
    950 N Cherry Ave
    Tucson AZ 85719 USA
    +1 520-318-8526
    E-mail: kgarmany@noao.edu

    The Magellanic Clouds are the two brightest nearby satellite galaxies to our own Milky Way galaxy. From a new study it appears that not only are they much bigger than astronomers calculated, but also have non-uniform structure at their outer edge, hinting at a rich and complex field of debris left over from their formation and interaction. This is an early result from a survey called SMASH, for “Survey of the MAgellanic Stellar History”, carried out by an international team of astronomers using telescopes that include the Blanco 4-meter at Cerro Tololo Inter-American Observatory (CTIO) in Chile and presented today at the 225th meeting of the American Astronomical Society in Seattle, Washington.

    CTIO Victor M Blanco 4m Telescope
    CTIO Victor M Blanco 4m Telescope interior
    CTIO Victor M. Blanco 4 meter Telescope

    The Large and Small Magellanic Clouds are dominant features in the Southern hemisphere sky. Although named after explorer Ferdinand Magellan who brought them to the attention of Europeans, they were already known to every early culture in the Southern hemisphere. The Large Cloud (LMC), covering about 5 degrees in angular size (10 lunar diameters), appears to the naked eye like a detached piece of the Milky Way. At a distance from us of about 160 thousand light years, even the brightest stars in these galaxies can’t be seen without a telescope.

    lmc
    The Large Magellanic Cloud

    s
    Small Magellanic Cloud

    As principal investigator Dr. David Nidever (University of Michigan) says, “We have a decent understanding of how large galaxies like the Milky Way form, but most galaxies in the universe are faint, distant, dwarf galaxies. The Magellanic Clouds are two of the few nearby dwarf galaxies, and SMASH is able to map out and study the structures in them like no other survey has been able to do before.”

    “We knew from the earlier work of SMASH team members that the LMC was larger than we thought, but those observations probed only 1 percent of the area that we need to explore. SMASH is probing an area 20 times larger, and is confirming beyond doubt that the LMC is really large while also giving us a chance to map its structure in detail.” said Dr. Knut Olsen (National Optical Astronomy Observatory) one of the leaders of the SMASH team. The team has identified stars belonging to the LMC at angular distances up to 20 degrees away, corresponding to 55 thousand light years. This was done using a new camera, dubbed DECam, mounted on the CTIO Blanco 4-meter telescope, which allows the SMASH team to identify faint stars over a much larger area than ever before.

    DECam
    DECam, built at FNAL

    With the Blanco telescope, SMASH can detect exceptionally diffuse stellar structures – up to 400,000 times fainter than the appearance of the faint band of the Milky Way in the night sky. This is possible because DECam can distinguish individual faint Magellanic stars over a huge area. (In astronomical parlance, the survey can reach a surface brightness limit of ~35 magnitudes per square arc second). That allows the team to detect stellar structures that were previously much too faint to see.

    The team is also exploring the Magellanic Stream, a gaseous structure that connects the two Clouds and extends in front and behind them. The existence of the Magellanic Stream, first detected with radio telescopes over 30 years ago, clearly indicates that the two galaxies are interacting with each other and with our Milky Way. Astronomers have long expected to also find stars in the Stream but so far none have been detected. It’s likely this is because the stellar component of the Stream is too faint to have been detected until the availability of the new camera. As Dr. Nidever said, “SMASH’s ability to reveal super-faint stellar structures should not only allow us to finally detect the stellar component of the Magellanic Stream but also map out its structure which will give us a much better understanding of the Magellanic Clouds’ interaction history.”

    See the full article here.

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    NOAO News
    NOAO is the US national research & development center for ground-based night time astronomy. In particular, NOAO is enabling the development of the US optical-infrared (O/IR) System, an alliance of public and private observatories allied for excellence in scientific research, education and public outreach.

    Our core mission is to provide public access to qualified professional researchers via peer-review to forefront scientific capabilities on telescopes operated by NOAO as well as other telescopes throughout the O/IR System. Today, these telescopes range in aperture size from 2-m to 10-m. NOAO is participating in the development of telescopes with aperture sizes of 20-m and larger as well as a unique 8-m telescope that will make a 10-year movie of the Southern sky.

    In support of this mission, NOAO is engaged in programs to develop the next generation of telescopes, instruments, and software tools necessary to enable exploration and investigation through the observable Universe, from planets orbiting other stars to the most distant galaxies in the Universe.

    To communicate the excitement of such world-class scientific research and technology development, NOAO has developed a nationally recognized Education and Public Outreach program. The main goals of the NOAO EPO program are to inspire young people to become explorers in science and research-based technology, and to reach out to groups and individuals who have been historically under-represented in the physics and astronomy science enterprise.

    About Our Observatories:
    Kitt Peak National Observatory (KPNO)

    Kitt Peak

    Kitt Peak National Observatory (KPNO) has its headquarters in Tucson and operates the Mayall 4-meter, the 3.5-meter WIYN , the 2.1-meter and Coudé Feed, and the 0.9-meter telescopes on Kitt Peak Mountain, about 55 miles southwest of the city.

    Cerro Tololo Inter-American Observatory (CTIO)

    NOAO Cerro Tolo

    The Cerro Tololo Inter-American Observatory (CTIO) is located in northern Chile. CTIO operates the 4-meter, 1.5-meter, 0.9-meter, and Curtis Schmidt telescopes at this site.

    The NOAO System Science Center (NSSC)

    Gemini North
    Gemini North

    Gemini South telescope
    Gemini South

    The NOAO System Science Center (NSSC) at NOAO is the gateway for the U.S. astronomical community to the International Gemini Project: twin 8.1 meter telescopes in Hawaii and Chile that provide unprecendented coverage (northern and southern skies) and details of our universe.

    NOAO is managed by the Association of Universities for Research in Astronomy under a Cooperative Agreement with the National Science Foundation.

     
  • richardmitnick 10:42 am on January 7, 2015 Permalink | Reply
    Tags: , , , , Cosmology   

    From Astronomy: “Making dreams reality” 

    Astronomy magazine

    Astronomy Magazine

    January 07, 2015
    Korey Haynes

    One of the coolest things about being at the American Astronomical Society (AAS) meeting is hearing about the future of space science straight from the source. Last night I got to hear about the far future of space observatories — what comes after the James Webb Space Telescope (JWST), set to launch in 2018. The next, next big project, currently dubbed the High Definition Space Telescope (if you don’t like it, the name will almost certainly change before launch), imagines the world’s leading ground-based telescopes of today, but in space.

    NASA Webb Telescope
    Webb

    The idea is for a 10- to 12-meter segmented mirror, which is similar to the currently existing Keck telescopes. It would fly, like JWST, at an Earth-Sun Lagranian point, and it would have capabilities from the ultraviolet to the infrared. In most ways, it would represent at least an order of magnitude improvement over JWST’s abilities.

    Keck Observatory
    Keck Observatory Interior
    Keck

    Why do we need an order of magnitude improvement over the most cutting-edge telescope we’re currently able to produce? Think of it this way: There only will be a handful of rocky planets close enough and bright enough for JWST to search for signs of life. It’s just not precise enough to study the farther, dimmer candidates satisfactorily. If the odds are only 1 in 10 that an Earth “twin” actually supports life (a reasonable fraction), do you want to take your chances and only able to study five planets? Better by far to study 50. That’s one of the many drivers to keep pushing for bigger, better telescopes for the future.

    While it may seem a bit premature to start thinking beyond JWST, it takes decades to walk a giant project like this from first concept to first light. JWST began its planning just after the launch of Hubble, so we’re actually right on track to start thinking about the succeeding generation, which would launch in the mid 2030s. By then, perhaps we even could fly servicing missions to such an observatory.

    Tuesday morning, we heard updates from the European Space Agency (ESA) on the Gaia mission, whose slogan is “a billion pixels for a billion stars.”

    ESA Gaia satellite
    Gaia

    Gaia is a space telescope with a gigapixel detector and two mirrors that fly in close formation. Its main purpose is astrometry, or measuring the positional change of stars on the sky, which Gaia accomplishes by observing them repeatedly as the spacecraft orbits. It can measure positions to such an accuracy that from Astronomy’s offices near Milwaukee, Wisconsin, it could measure the width of a human hair in Washington, D.C.

    Gaia is the successor to a mission called Hipparcos that operated between 1989 and 1993. Hipparcos was a revolutionary project, and its catalog consists of 120,000 stars. Gaia will measure more than one thousand million stars when its survey is complete. With a catalog that enormous and precise, it will find thousands of exoplanets through radial velocity searches. It will tell us unprecedented detail about stellar populations and even deliver detailed information about near-Earth objects.

    ESA Hipparcus spacecraft
    Hipparcos

    Gaia was launched back in 2013 and started collecting data in July. It will take almost two more years before it returns its first big results in astrometry, but it’s already found its first supernova and is working just as expected.

    Gaia will return the data set of a lifetime. It’s the manifestation of a dream when astronomers looked at Hipparcos and said, “Yes, but we can do even better.” Now astronomers right here, right now, are looking at JWST, the pinnacle of space observatories, and thinking the same thing. Imagine what we’ll be imagining in twenty more years.

    See the full article here.

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  • richardmitnick 10:08 am on January 7, 2015 Permalink | Reply
    Tags: , , , Cosmology, Dennis Overbye - New York Times   

    From NYT: Dennis Overbye “So Many Earth-Like Planets, So Few Telescopes” 

    New York Times

    The New York Times

    JAN. 6, 2015

    NYT Dennis Overbye
    DENNIS OVERBYE

    It’s a big universe, but it’s full of small planets.

    Astronomers announced on Tuesday that they had found eight new planets orbiting their stars at distances compatible with liquid water, bringing the total number of potentially habitable planets in the just-right “Goldilocks” zone to a dozen or two, depending on how the habitable zone of a star is defined.

    NASA’s Kepler spacecraft, now in its fifth year of seeking out the shadows of planets circling other stars, has spotted hundreds, and more and more of these other worlds look a lot like Earth — rocky balls only slightly larger than our own home, that with the right doses of starlight and water could turn out to be veritable gardens of microbial Eden.

    NASA Kepler Telescope
    Kepler

    As the ranks of these planets grow, astronomers are planning the next step in the quest to end cosmic loneliness: gauging which hold the greatest promise for life and what tools will be needed to learn about them.
    Continue reading the main story

    The planets unveiled on Tuesday were detected by a group led by Guillermo Torres of the Harvard-Smithsonian Center for Astrophysics.

    On Monday, another group of astronomers said they had managed to weigh precisely a set of small planets and found that their densities and compositions almost exactly matched those of Earth.

    Courtney Dressing, also of the Harvard-Smithsonian Center for Astrophysics, said at a news conference, “I’m going to give you the recipe for a rocky planet.”

    She began, “Take one cup of magnesium …”

    Both groups announced their findings at a meeting of the American Astronomical Society in Seattle.

    Reviewing the history of exoplanets, Debra Fischer, a Yale astronomer, recalled that the first discovery of a planet orbiting another normal star, a Jupiter-like giant, was 20 years ago. Before that, she said, astronomers worried that “maybe the ‘Star Trek’ picture of the universe was not right, and there is no life anywhere else.”

    Dr. Fischer called the progress in the last two decades “incredibly moving.”

    And yet we still do not have a clue that we are not alone.

    And yet, I can’t help but feel a certain measure of bittersweetness, because without a dramatic paradigm shift in propulsion technology, even a nearby Earth 2.0 will be forever beyond our reach.

    So far, Kepler has discovered 4,175 potential planets, and 1,004 of them have been confirmed as real, according to Michele Johnson, a spokeswoman for NASA’s Ames Research Center, which operates Kepler.

    Most of them, however, including those announced Tuesday, are hundreds of light-years away, too far for detailed study. We will probably never know any more about these particular planets than we do now.

    “We can count as many as we like,” said Sara Seager, a planet theorist at the Massachusetts Institute of Technology who was not involved in the new work, “but until we can observe the atmospheres and assess their greenhouse gas power, we don’t really know what the surface temperatures are like.”

    Still, she added, “it’s heartening to have such a growing list.”

    Finding Goldilocks planets closer to home will be the job of the Transiting Exoplanet Survey Satellite, to be launched in 2017. But if we want to know what the weather is like on these worlds, whether there is water or even life, more powerful instruments will be needed.

    NASA TESS
    TESS

    Dr. Seager is heading a NASA study investigating the concept of a starshade, which would float in front of a space telescope and block light from a star so that its much fainter planets would be visible.

    Another group, led by Karl Stapelfeldt of NASA’s Goddard Space Flight Center, is studying a method known as a coronagraph, in which the occulting disk is inside the telescope.

    Both studies are expected to be completed in the next few months, and could affect plans for a former spy telescope bequeathed to NASA three years ago. Astronomers hope to launch it in the early 2020s to study dark energy, and they plan to include a coronagraph to search for exoplanets, according to Paul Schechter of M.I.T., chairman of a design team. Depending on the probe’s orbit, Dr. Seager said, it could also be made “starshade ready.”

    NASA’s James Webb Space Telescope, due for a 2018 launch, will have a coronagraph capable of seeing Jupiter-size planets, but it is too late to adapt it to a starshade.

    NASA Webb Telescope
    Webb

    Meanwhile, Dr. Seager and Julianne Dalcanton of the University of Washington are writing a separate report for a consortium of universities that runs observatories. The goal is to have a pool of dozens of “exo-Earths” to study in order to have any chance of seeing signs of life or understanding terrestrial planets, Dr. Seager said. Amassing them will require a space telescope 10 or 12 meters in diameter (the Webb will be 6.5 meters, and the largest currently on Earth is 10).

    All of this will be grist for the mill at the end of the decade when a panel of the National Academy of Sciences produces its wish list for astronomy in the 2020s.

    For all of Kepler’s bounty, a planet like Earth, of the same size orbiting the same type of star, has not yet been confirmed. The most terrestrial of the new worlds announced Tuesday are a pair known as Kepler 438b and Kepler 442b, both orbiting stars slightly smaller, cooler and redder than our sun. Kepler 438b is only 12 percent larger than Earth in diameter and has a 35-day year; Kepler 442 is a third larger than Earth and has a 112-day year.

    “All these are small, all are potentially habitable,” said Doug Caldwell of the SETI Institute and NASA Ames at a news conference in Seattle.

    In a news release, Dr. Torres said, “Most of these planets have a good chance of being rocky, like Earth.” That thought was reinforced by his colleagues, led by Ms. Dressing, a doctoral candidate at Harvard. Her group combined data from Kepler, which measures the sizes of planets, with spectrographic observations from an Italian telescope in the Canary Islands. That instrument measures planets’ masses to determine their densities, and by combining the information Ms. Dressing’s group was able to infer the densities and compositions of a set of small planets.

    Telescoipio Nazionale Galileo
    Telescopio Nazionale Galileo Interior
    Telescopio Nazionale Galileo

    All five of the planets smaller than 1.6 times the size of Earth fell on a line consistent with Earth and Venus. Planets larger than that, Ms. Dressing and her colleagues found, were fluffier, perhaps because as planets get bigger their mass and gravity increase, and they are better able to hang on to gas and lighter components.

    The work complements and tightens studies done last year by Geoffrey Marcy and his colleagues at the University of California, Berkeley; that group looks into the nature of so-called super Earths, planets bigger than ours and smaller than Neptune.

    There are no planets in this range in our solar system, but according to Kepler they are common in the galaxy. Are they rocks like Earth or blobs like Neptune? The break point now seems to be 1.6 times the size of Earth, according to Ms. Dressing, and it is on those planets, perhaps, that we should concentrate our search for cosmic company.

    As she said in her presentation, “Doubling the recipe doesn’t work.”

    See the full article here.

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  • richardmitnick 7:34 am on January 7, 2015 Permalink | Reply
    Tags: , , , Cosmology,   

    From ESO: “Where Did All the Stars Go?” 


    European Southern Observatory

    7 January 2015
    Richard Hook
    ESO education and Public Outreach Department
    Garching bei München, Germany

    Tel: +49 89 3200 6655
    Email: rhook@eso.org

    Some of the stars appear to be missing in this intriguing new ESO image. But the black gap in this glitteringly beautiful starfield is not really a gap, but rather a region of space clogged with gas and dust. This dark cloud is called LDN 483 — for Lynds Dark Nebula 483. Such clouds are the birthplaces of future stars. The Wide Field Imager, an instrument mounted on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile, captured this image of LDN 483 and its surroundings.

    ESO Wide Field Imager 2.2m LaSilla
    WFI

    ESO MPG 2.2 meter telescope
    MPG/ESO 2.2-metre telescope

    ESO LaSilla Long View
    ESO LaSilla

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    LDN 483 [1] is located about 700 light-years away in the constellation of Serpens (The Serpent). The cloud contains enough dusty material to completely block the visible light from background stars. Particularly dense molecular clouds, like LDN 483, qualify as dark nebulae because of this obscuring property. The starless nature of LDN 483 and its ilk would suggest that they are sites where stars cannot take root and grow. But in fact the opposite is true: dark nebulae offer the most fertile environments for eventual star formation.

    Astronomers studying star formation in LDN 483 have discovered some of the youngest observable kinds of baby stars buried in LDN 483’s shrouded interior. These gestating stars can be thought of as still being in the womb, having not yet been born as complete, albeit immature, stars.

    In this first stage of stellar development, the star-to-be is just a ball of gas and dust contracting under the force of gravity within the surrounding molecular cloud. The protostar is still quite cool — about –250 degrees Celsius — and shines only in long-wavelength submillimetre light [2]. Yet temperature and pressure are beginning to increase in the fledgling star’s core.

    This earliest period of star growth lasts a mere thousands of years, an astonishingly short amount of time in astronomical terms, given that stars typically live for millions or billions of years. In the following stages, over the course of several million years, the protostar will grow warmer and denser. Its emission will increase in energy along the way, graduating from mainly cold, far-infrared light to near-infrared and finally to visible light. The once-dim protostar will have then become a fully luminous star.

    As more and more stars emerge from the inky depths of LDN 483, the dark nebula will disperse further and lose its opacity. The missing background stars that are currently hidden will then come into view — but only after the passage of millions of years, and they will be outshone by the bright young-born stars in the cloud [3].
    Notes

    [1] The Lynds Dark Nebula catalogue was compiled by the American astronomer Beverly Turner Lynds, and published in 1962. These dark nebulae were found from visual inspection of the Palomar Sky Survey photographic plates.

    [2] The Atacama Large Millimeter/submillimeter Array (ALMA), operated in part by ESO, observes in submillimetre and millimetre light and is ideal for the study of such very young stars in molecular clouds.

    [3] Such a young open star cluster can be seen here, and a more mature one here.

    See the full article here.

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