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  • richardmitnick 3:28 pm on December 22, 2014 Permalink | Reply
    Tags: , Astrophysics, , , , ,   

    From IceCube: “Gamma-ray bursts are not main contributors to the astrophysical neutrino flux in IceCube” 

    icecube
    IceCube South Pole Neutrino Observatory

    22 Dec 2014
    Silvia Bravo

    Gamma-ray bursts (GRBs) were once the most promising candidate source of ultra-high-energy cosmic rays (UHECRs). They release extremely large amounts of energy in short periods of time, so if they could accelerate protons as they do electrons, then GRBs could account for most of the observed UHECRs.

    But along comes IceCube, the first gigaton neutrino detector ever built, ready to dig into the origin of UHECRs using neutrinos. There’s a whole universe in which to look for a signal but, to test GRBs as possible sources, they started with a search for neutrinos in coincidence with observed GBRs. Previous results, published by the IceCube Collaboration in 2012 in Nature, found no such coincidence. This cast doubt on GRBs as the main source of UHECRs. In a follow-up study submitted today to the Astrophysical Journal Letters, the collaboration shows that the contribution of GRBs to the observed astrophysical neutrino flux cannot be larger than about 1%.

    The study also sets the most stringent limits yet on GRB neutrino production, excluding much of the parameter space for the most popular models. The collaboration is now also providing a tool to set limits on other GRB models using IceCube data.

    grb
    The jet from a gamma-ray burst emerging at nearly light speed. Image credit: NASA / Swift / Cruz deWilde.

    NASA SWIFT Telescope
    NASA/Swift

    One may wonder how observing neutrinos in Antarctic ice tells us anything about cosmic rays and GRBs. The answer is simple, if you ask a physicist: neutrinos are an unambiguous signature of proton acceleration. And cosmic rays are, in their vast majority, very high energy protons.

    That cosmic rays exist at energies up to 10^20 eV is a fact; we have observed them with all sort of detectors since their discovery by Victor [Francis] Hess back in 1912. Physicists have developed several models that could explain how and where cosmic rays can be accelerated to such extreme energies. All of these models also tell us that any cosmic proton accelerator that we can imagine would also be a very high energy neutrino generator. While cosmic rays are scrambled by intergalactic magnetic fields, neutrinos travel in straight paths, potentially allowing us to identify their sources. For this reason, the search for the sources of cosmic rays has also become the search for very high energy neutrinos.

    IceCube, the first detector to measure a very high energy neutrino flux, is now squeezing every bit of information out of its data, to learn more about the origins of those neutrinos and thus of cosmic rays. In the current research, IceCube has looked for a neutrino signature in coincidence with over 500 GRBs observed during the data-taking period from April 2008 to May 2012. A single low-significance neutrino was found, confirming previous results by the collaboration. However, this data sample was much larger, including the first data from the completed detector and allowing still more stringent limits on GRB neutrino production.

    GRBs were once very promising candidates for the source of UHECRs. Corresponding author Michael Richman from University of Maryland notes that “using data taken from one year of operation of the completed detector, IceCube has already cast doubt on that hypothesis.” IceCube’s recent observation of an astrophysical neutrino flux marks a new era of neutrino astronomy. This flux is compatible with the expectation from cosmic ray production. While GRBs are excluded as dominant sources of either UHECRs or the diffuse astrophysical neutrinos, ongoing analyses will shed new light on these mysterious signals.

    + Info Search for Prompt Neutrino Emission from Gamma-Ray Bursts with IceCube, IceCube Collaboration: M.G. Aartsen et al. Submitted to Astrophysical Journal Letters, arxiv.org/abs/1412.6510

    See the full article here.

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    ICECUBE neutrino detector
    IceCube is a particle detector at the South Pole that records the interactions of a nearly massless sub-atomic particle called the neutrino. IceCube searches for neutrinos from the most violent astrophysical sources: events like exploding stars, gamma ray bursts, and cataclysmic phenomena involving black holes and neutron stars. The IceCube telescope is a powerful tool to search for dark matter, and could reveal the new physical processes associated with the enigmatic origin of the highest energy particles in nature. In addition, exploring the background of neutrinos produced in the atmosphere, IceCube studies the neutrinos themselves; their energies far exceed those produced by accelerator beams. IceCube is the world’s largest neutrino detector, encompassing a cubic kilometer of ice.

     
  • richardmitnick 2:58 pm on December 22, 2014 Permalink | Reply
    Tags: , Astrophysics, , , ,   

    From JPL: “Sun Sizzles in High-Energy X-Rays” 

    JPL

    December 22, 2014
    Whitney Clavin
    Jet Propulsion Laboratory, Pasadena, Calif.
    818-354-4673
    whitney.clavin@jpl.nasa.gov

    For the first time, a mission designed to set its eyes on black holes and other objects far from our solar system has turned its gaze back closer to home, capturing images of our sun. NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, has taken its first picture of the sun, producing the most sensitive solar portrait ever taken in high-energy X-rays.

    NASA NuSTAR
    NU-STAR

    “NuSTAR will give us a unique look at the sun, from the deepest to the highest parts of its atmosphere,” said David Smith, a solar physicist and member of the NuSTAR team at University of California, Santa Cruz.

    Solar scientists first thought of using NuSTAR to study the sun about seven years ago, after the space telescope’s design and construction was already underway (the telescope launched into space in 2012). Smith had contacted the principal investigator, Fiona Harrison of the California Institute of Technology in Pasadena, who mulled it over and became excited by the idea.

    “At first I thought the whole idea was crazy,” says Harrison. “Why would we have the most sensitive high energy X-ray telescope ever built, designed to peer deep into the universe, look at something in our own back yard?” Smith eventually convinced Harrison, explaining that faint X-ray flashes predicted by theorists could only be seen by NuSTAR.

    While the sun is too bright for other telescopes such as NASA’s Chandra X-ray Observatory, NuSTAR can safely look at it without the risk of damaging its detectors. The sun is not as bright in the higher-energy X-rays detected by NuSTAR, a factor that depends on the temperature of the sun’s atmosphere.

    NASA Chandra Telescope
    NASA Chandra schematic
    Chandra X-ray space observatory

    s
    X-rays stream off the sun in this image showing observations from by NASA’s Nuclear Spectroscopic Telescope Array, or NuSTAR, overlaid on a picture taken by NASA’s Solar Dynamics Observatory (SDO) .Image credit: NASA/JPL-Caltech/GSFC

    NASA Solar Dynamics Observatory
    NASA Solar Dynamics Observatory schematic

    This first solar image from NuSTAR demonstrates that the telescope can in fact gather data about sun. And it gives insight into questions about the remarkably high temperatures that are found above sunspots — cool, dark patches on the sun. Future images will provide even better data as the sun winds down in its solar cycle.

    “We will come into our own when the sun gets quiet,” said Smith, explaining that the sun’s activity will dwindle over the next few years.

    With NuSTAR’s high-energy views, it has the potential to capture hypothesized nanoflares — smaller versions of the sun’s giant flares that erupt with charged particles and high-energy radiation. Nanoflares, should they exist, may explain why the sun’s outer atmosphere, called the corona, is sizzling hot, a mystery called the “coronal heating problem.” The corona is, on average, 1.8 million degrees Fahrenheit (1 million degrees Celsius), while the surface of the sun is relatively cooler at 10,800 Fahrenheit (6,000 degrees Celsius). It is like a flame coming out of an ice cube. Nanoflares, in combination with flares, may be sources of the intense heat.

    If NuSTAR can catch nanoflares in action, it may help solve this decades-old puzzle.

    “NuSTAR will be exquisitely sensitive to the faintest X-ray activity happening in the solar atmosphere, and that includes possible nanoflares,” said Smith.

    What’s more, the X-ray observatory can search for hypothesized dark matter particles called axions. Dark matter is five times more abundant than regular matter in the universe. Everyday matter familiar to us, for example in tables and chairs, planets and stars, is only a sliver of what’s out there. While dark matter has been indirectly detected through its gravitational pull, its composition remains unknown.

    It’s a long shot, say scientists, but NuSTAR may be able spot axions, one of the leading candidates for dark matter, should they exist. The axions would appear as a spot of X-rays in the center of the sun.

    Meanwhile, as the sun awaits future NuSTAR observations, the telescope is continuing with its galactic pursuits, probing black holes, supernova remnants and other extreme objects beyond our solar system.

    NuSTAR is a Small Explorer mission led by Caltech and managed by NASA’s Jet Propulsion Laboratory, also in Pasadena, for NASA’s Science Mission Directorate in Washington. The spacecraft was built by Orbital Sciences Corporation, Dulles, Virginia. Its instrument was built by a consortium including Caltech; JPL; the University of California, Berkeley; Columbia University, New York; NASA’s Goddard Space Flight Center, Greenbelt, Maryland; the Danish Technical University in Denmark; Lawrence Livermore National Laboratory, Livermore, California; ATK Aerospace Systems, Goleta, California; and with support from the Italian Space Agency (ASI) Science Data Center.

    NuSTAR’s mission operations center is at UC Berkeley, with the ASI providing its equatorial ground station located at Malindi, Kenya. The mission’s outreach program is based at Sonoma State University, Rohnert Park, California. NASA’s Explorer Program is managed by Goddard. JPL is managed by Caltech for NASA.

    For more information, visit:

    http://www.nasa.gov/nustar

    http://www.nustar.caltech.edu

    See the full article here.

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    NASA JPL Campus

    Jet Propulsion Laboratory (JPL) is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. Although the facility has a Pasadena postal address, it is actually headquartered in the city of La Cañada Flintridge [1], on the northwest border of Pasadena. JPL is managed by the nearby California Institute of Technology (Caltech) for the National Aeronautics and Space Administration. The Laboratory’s primary function is the construction and operation of robotic planetary spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASA’s Deep Space Network.

    Caltech Logo
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  • richardmitnick 2:24 pm on December 22, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From New Scientist: “Europa’s geysers disappear in a cloud of mystery” 

    NewScientist

    New Scientist

    19 December 2014
    Adam Mann

    Now you see it, now you don’t. Now you see it, now you don’t. Now you see it, now you don’t. Europa’s 200-kilometre-high water jets may have been downgraded from major discovery to major mystery. Follow-up searches have yet to see the geysers again, while older observations don’t seem to support their existence. Some people are now wondering if the jets are far rarer than expected – or if they were ever there to begin with.

    e
    Europa

    “It’s a real puzzle now,” said Donald Shemansky of the University of Southern California in Los Angeles, who presented the analysis of spacecraft data at the American Geophysical Union conference in San Francisco on 18 December that contradicted the idea of regularly erupting plumes.

    We already suspected that Jupiter’s icy moon Europa had a vast ocean of water beneath its frozen crust. But excitement surged last year when a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, Texas, announced that the Hubble Space Telescope had spotted a small bump of water coming from Europa’s south pole, meaning the moon was shooting its insides out into space.

    NASA Hubble Telescope
    NASA Hubble schematic
    NAS/ESA Hubble

    This made the moon an ideal target for orbital probes to attempt to fly through the jets and detect the presence of life.

    Shy geysers

    But the geysers have yet to reappear. That doesn’t necessarily mean they don’t exist, says Roth – but they “are more transient than we would have hoped”.

    Shemansky’s results further muddle the spouting waters. His team looked at data from NASA’s Cassini spacecraft, which flew by Jupiter in 2001 on its way to Saturn.

    NASA Cassini Spacecraft
    NASA/Cassini

    Another moon of Jupiter, Io, is extremely active, with constant volcanic eruptions on its surface that shoot charged particles of sulphur and oxygen out into space. These ions get swept up in Jupiter’s strong magnetic field, forming a ring of plasma around the gas giant.

    Io
    Io

    If Europa’s plumes had been active in 2001, some of their water molecules should have been split by Jupiter’s radiation and dumped hydrogen atoms into space. For a short time, these hydrogen atoms would have joined Jupiter’s plasma torus, cooling the other charged particles.

    Thin air

    But when Shemansky and his team looked at the Cassini data, they saw nothing like that. Furthermore, they argue that Europa’s atmosphere is about two orders of magnitude thinner than previously believed, which seems impossible if it is regularly being replenished with water from the inside.

    Not so fast, says Kurt Retherford, also of the Southwest Research Institute and another of the plume’s original discoverers. Cassini zipped by Jupiter at a significant distance, making hydrogen atoms difficult to detect even if they were present.

    “We would say using their technique, they couldn’t possibly find water,” he said.

    Retherford, Roth and their colleagues are now preparing a paper to rebut Shemansky’s analysis. Their main worry is about how Shemansky was modelling the plasma around Jupiter.

    “It contradicts everything that’s been done before in Europa’s environment,” said Roth.

    At the limits

    The original detection of plumes was at the limit of Hubble’s capabilities, and finding them again may be difficult for many reasons. Until a definitive repeat observation is made, many in the field are hedging their bets.

    “The Hubble observation was so borderline that maybe they were fooled, or they got lucky and caught an event that’s not so common,” said Robert Pappalardo of NASA’s Jet Propulsion Laboratory in Pasadena, California.

    NASA is expected to decide next year whether to send a robotic mission to the frozen moon, so knowing if the jets are real will be crucial in guiding how researchers design instruments to either try to confirm their existence or sample their contents.

    Whether the geysers exist or not, Pappalardo still sees Europa as a great scientific destination. “Either way, the plumes certainly kicked Europa up in the public consciousness.” 200-kilometre-high water jets may have been downgraded from major discovery to major mystery. Follow-up searches have yet to see the geysers again, while older observations don’t seem to support their existence. Some people are now wondering if the jets are far rarer than expected – or if they were ever there to begin with.

    “It’s a real puzzle now,” said Donald Shemansky of the University of Southern California in Los Angeles, who presented the analysis of spacecraft data at the American Geophysical Union conference in San Francisco on 18 December that contradicted the idea of regularly erupting plumes.

    We already suspected that Jupiter’s icy moon Europa had a vast ocean of water beneath its frozen crust. But excitement surged last year when a team led by Lorenz Roth of the Southwest Research Institute in San Antonio, Texas, announced that the Hubble Space Telescope had spotted a small bump of water coming from Europa’s south pole, meaning the moon was shooting its insides out into space.

    This made the moon an ideal target for orbital probes to attempt to fly through the jets and detect the presence of life.

    Whether the geysers exist or not, Pappalardo still sees Europa as a great scientific destination. “Either way, the plumes certainly kicked Europa up in the public consciousness.”

    See the full article here.

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  • richardmitnick 5:32 am on December 22, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From RAS: “The Milky Way’s new neighbour” 

    Royal Astronomical Society

    Royal Astronomical Society

    19 December 2014
    Media contact
    Robert Massey
    Royal Astronomical Society
    Mob: +44 (0)794 124 8035
    rm@ras.org.uk

    Science contact
    Prof Dimitry Makarov
    Special Astrophysical Observatory
    Nizhniy Arkhyz
    Karachai-Cherkessia
    Russia
    Tel: +7 87822 93404
    dim@sao.ru

    The Milky Way, the galaxy we live in, is part of a cluster of more than 50 galaxies that make up the ‘Local Group’, a collection that includes the famous Andromeda galaxy and many other far smaller objects. Now a Russian-American team have added to the canon, finding a tiny and isolated dwarf galaxy almost 7 million light years away. Their results appear in Monthly Notices of the Royal Astronomical Society.

    l
    Local Group

    a
    The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. The image also shows Messier Objects 32 and 110, as well as NGC 206 (a bright star cloud in the Andromeda Galaxy) and the star Nu Andromedae. This image was taken using a hydrogen-alpha filter.
    Adam Evans

    The team, led by Prof Igor Karachentsev of the Special Astrophysical Observatory in Karachai-Cherkessia, Russia, found the new galaxy, named KKs3, using the Hubble Space Telescope Advanced Camera for Surveys (ACS) in August 2014. Kks3 is located in the southern sky in the direction of the constellation of Hydrus and its stars have only one ten-thousandth of the mass of the Milky Way.

    NASA Hubble Telescope
    NASA Hubble schematic
    Hubble

    NASA Hubble ACS
    HUbble ACS

    h
    The core of the galaxy is the right hand dark object at the top centre of the image, with its stars spreading out over a large section around it. (The left hand of the two dark objects is a much nearer globular star cluster.) Credit: D. Makarov. Kks3 is a ‘dwarf spheroidal or dSph galaxy’ , lacking features like the spiral arms found in our own galaxy. These systems also have an absence of the raw materials (gas and dust) needed for new generations of stars to form, leaving behind older and fainter relics. In almost every case, this raw material seems to have been stripped out by nearby massive galaxies like Andromeda, so the vast majority of dSph objects are found near much bigger companions.

    Isolated objects must have formed in a different way, with one possibility being that they had an early burst of star formation that used up the available gas resources. Astronomers are particularly interested in finding dSph objects to understand galaxy formation in the universe in general, as even HST struggles to see them beyond the Local Group. The absence of clouds of hydrogen gas in nebulae also makes them harder to pick out in surveys, so scientists instead try to find them by picking out individual stars.

    For that reason, only one other isolated dwarf spheroidal, KKR 25, has been found in the Local Group, a discovery made by the same group back in 1999.

    Team member Prof Dimitry Makarov, also of the Special Astrophysical Observatory, commented: “Finding objects like Kks3 is painstaking work, even with observatories like the Hubble Space Telescope. But with persistence, we’re slowly building up a map of our local neighbourhood, which turns out to be less empty than we thought. It may be that are a huge number of dwarf spheroidal galaxies out there, something that would have profound consequences for our ideas about the evolution of the cosmos.”

    The team will continue to look for more dSph galaxies, a task that will become a little easier in the next few years, once instruments like the James Webb Space Telescope and the European Extremely Large Telescope begin service.

    See the full article here.

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    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 8:09 pm on December 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , , ,   

    From Jodrell Bank: “Giant radio loops: What are they?” 

    Jodrell Bank Lovell Telescope
    Lovell

    Jodrell Bank Centre for Astrophysics

    07 Nov 2014
    Katie Brewin and Aeron Howarth
    Media Relations Officer
    The University of Manchester
    Tel: 0161 275 8387
    Email: katie.brewin@manchester.ac.uk or aeron.howarth@manchester.ac.uk

    The radio sky is full of giant loops and elongated features which have been known since the earliest days of radio astronomy. Using data from the WMAP satellite and reprocessed classic maps of the sky, a team of astronomers at Jodrell Bank suggest these loops may be produced by a nearby expanding shell driven by supernova explosions and the radiation from massive stars.

    NASA WMAP
    NASA WMAP satellite
    NASA/WMAP

    The study of the diffuse Galactic radio emission is nearly as old as radio-astronomy. The first extraterrestrial radio signal detected by Karl [Guth] Jansky in the early 1930s originated from the central region of our Galaxy.

    Later, in the 1950s, maps covering much of the sky were made which showed large elongated features and loops. Various different hypotheses for the origin of these structures are still being discussed today. The emission from the loops is produced by synchrotron radiation, where highly energetic electrons travel spiralling around magnetic field lines at almost the speed of light.

    m
    The famous 408 MHz map of the radio sky published by Haslam et al (1982). This version has been reprocessed by Remazeilles et al (2014).

    In 1982, Glyn Haslam and colleagues presented a full sky map at a radio frequency of 408 MHz. The map had taken more than a decade to produce and combined data from the Jodrell Bank, Effelsberg and Parkes radio telescopes. This is the most widely used synchrotron template of the sky. In this map, four Loops are visible but they are difficult to isolate from a smooth diffuse component.

    Max Planck Effelberg Radio telescope
    Effelsberg Readio Telescope

    CSIRO Parkes Observatory
    CSIRO/Parks

    Now, using data available from the WMAP satellite, we can see for the first time how the polarised radio sky looks at high radio frequencies (~30 GHz). Surprisingly, the sky is covered by a number of bright filaments, without the uniform smooth background which dominates the radio continuum maps.

    We have catalogued these new filaments and tested a model to explain the origin of some of these features. We believe that they might be caused by the interaction between an expanding shell in the solar vicinity with the magnetic field of the Galaxy. The expanding shell, powered by supernova events and the radiation from massive stars compresses the magnetic field around it, increasing the synchrotron emission from the shell. This simple model reproduces well the data in most of the areas studied.

    See the full article here.

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    Jodrell Bank Centre for Astrophysics comprises research activities in astronomy and astrophysics at The University of Manchester, the world leading facilities of the Jodrell Bank Observatory, the e-MERLIN/VLBI National Facility and the Project Development Office of the Square Kilometre Array.

    Jodrell Bank e-Merlin

    SKA Square Kilometer Array

     
  • richardmitnick 6:13 am on December 21, 2014 Permalink | Reply
    Tags: Astrophysics, , , , ,   

    From Seth Shostak at SETI: “Mars Methane: Life at Last?” 


    SETI Institute

    Dec 20, 2014

    SETI Seth Shostak
    Dr. Seth Shostak, Senior Astronomer and Director of SETI Research

    m

    Mars is a tease.

    It seems that discoveries hinting at life on the Red Planet are as recurrent as Kansas hay fever. Open up the science section of any periodical, and you’ll invariably trip across new research encouraging us to believe that somewhere, skulking in the vast, dry landscapes of that desolate world, are small, wiggling creatures — fellow inhabitants of the solar system.

    Such enticing tidbits are nothing new. Their modern incarnation dates back to the early 1900s, when astronomer Percival Lowell promoted the existence of Martians who had trussed their planet with irrigation canals. This idea was well received by the public, but the astronomical community was at first skeptical, and eventually dismissive. By the First World War, these sluice-happy Martians were vaporware.

    As the century ground on, additional see-saw arguments for martian life made regular appearances. In the 1970s, the Viking Landers, with the best science instrumentation NASA could launch, went looking for life in the martian dirt. The verdict was that they didn’t find any. But one member of the Viking biology team doesn’t agree. Was it a hit or a whiff? We still can’t say for sure.

    NASA Viking
    NASA/Viking

    Then in 1996, claims of fossilized microbes in a meteorite known to come from Mars became the biggest science news story of the year. But were the seductive squiggles seen under the microscope really dead Red Planet microbes, or were they just inanimate features that mimicked croaked critters? Again, the jury has not returned to the court room.

    This litany of teases continues today with the saga of martian methane.

    Methane is best known on Earth as natural gas, and there’s a good chance it’s powering the device you’re using to read this. It’s the simplest of the organic molecules. “Organic,” by the way, doesn’t mean that it’s necessarily the product of biology, or that it was grown on a farm that shuns pesticides. It just means that the molecule incorporates carbon as one of its constituent elements. Since carbon has four covalent bonds, the simplest molecule you can make with this stuff is by attaching a hydrogen atom to each of these “chemical arms.” CH4 is the result, known to savvy 11th graders as methane.

    But in the context of extraterrestrial life, methane is important as a possible biomarker. It’s the exhaust gas of many forms of life on Earth — bacteria, most notably, but also slightly bulkier organisms such as cattle and pigs. If you detect methane in a planet’s atmosphere, you may have found pigs in space. Or more likely, microbes in space.

    In 2004, the Europeans launched the Mars Express orbiter, and did just that. They claimed that their spacecraft had spectroscopically sniffed clouds of methane wafting above the Red Planet. American astronomers, using ground-based telescopes, also thought they had sensed this gas. The claim was important, if true, because CH4 could be caused by underground, martian bacteria. If so, this would be the first detection of life beyond Earth.

    ESA Mars Express OrbiterESA Mars Express schematic
    ESA/Mars Express

    And even more, it would be living life. Not the dead microbes supposedly entombed in a meteorite, but metabolizing Martians that were still kicking. That’s because ultraviolet light from the Sun, untroubled by an ozone layer that Mars doesn’t have, would take apart any methane molecules in the atmosphere within 300 years or so. So if there’s methane around, it’s today’s methane (note to reader: for astronomers, 300 years ago is the same as “today”).

    Given this back story, you can imagine the considerable interest when NASA’s Curiosity rover bounced onto the sands of our little ruddy buddy in 2012, equipped with instruments that could also check for methane. The result, announced in September 2013, was that it couldn’t find any at a level under a part per billion, or roughly ten times lower than expected on the basis of the earlier measurements. You might guess that maybe Curiosity had the bad luck to land in a spot far from the madding, methane cloud. Sure, but scientists figure that — thanks to the circulation of its thin atmosphere — any gas spewed out in one spot would get spread around the entire planet within months. You should be able to detect it anywhere, if there’s enough of it.

    NASA Mars Curiosity Rover
    Curiosity

    The 2013 negative result from Curiosity was, indeed, both curious and a downer. But this week, researchers attending a conference of the American Geophysical Union in San Francisco heard of the detection of a sudden spike in methane. In a truly remarkable measurement by Curiosity, we find that the gas is back.

    That’s exciting news, but history cautions us not to party hearty just yet. Methane can be produced by geophysics as well as biology, when rocks and water interact chemically. Just because it smells like a duck, doesn’t mean it’s a duck.

    So what gives? No one’s sure yet; the obvious variability in the presence of methane suggests local sources, but the big question is whether the source is geophysical or biological.

    Nathalie Cabrol, a SETI Institute astrobiologist who is especially interested in the habitability of Mars, said, “The good news is that we now know sources of methane exist. This is something that we’ve measured.”

    Cabrol is cautious about concluding that these latest discoveries are even semi-solid evidence for biology, but there’s little doubt that such a scenario is possible.

    “There may not be an easy way to untangle whether the source of the gas is geophysical or biological,” Cabrol notes. “But if life evolved on Mars and survived eons of sudden and drastic climate changes, it might have evolved strategies analogous to dormant species on Earth. Bacteria can survive millions of years in terrestrial permafrost, awaiting the return of favorable conditions to start up their metabolism and multiply.”

    It might be life, or it might not be. But the good news is that we now have evidence of some sort of activity under the surface of Mars — phenomena subject to solid, repeatable measurement.

    Long everyone’s favorite place to search for extraterrestrial life, the Red Planet continues to taunt us a century after Percival Lowell assured us that it was both inhabited and cultivated. At least the first is still possible.

    See the full article here.

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  • richardmitnick 5:49 am on December 21, 2014 Permalink | Reply
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    From SPACE.com: “How Was the Moon Formed?” 2013 

    space-dot-com logo

    SPACE.com

    After the sun spun to light, the planets of the solar system began to form. But it took another hundred million years for Earth’s moon to spring into existence. There are three theories as to how our planet’s satellite could have been created: the giant impact hypothesis, the co-formation theory and the capture theory.

    Giant impact hypothesis

    This is the prevailing theory supported by the scientific community. Like the other planets, the Earth formed from the leftover cloud of dust and gas orbiting the young sun. The early solar system was a violent place, and a number of bodies were created that never made it to full planetary status. According to the giant impact hypothesis, one of these crashed into Earth not long after the young planet was created.

    Known as Theia, the Mars-size body collided with Earth, throwing vaporized chunks of the young planet’s crust into space. Gravity bound the ejected particles together, creating a moon that is the largest in the solar system in relation to its host planet. This sort of formation would explain why the moon is made up predominantly of lighter elements, making it less dense than Earth — the material that formed it came from the crust, while leaving the planet’s rocky core untouched. As the material drew together around what was left of Theia’s core, it would have centered near Earth’s ecliptic plane, the path the sun travels through the sky, which is where the moon orbits today.

    Co-formation theory

    Moons can also form at the same time as their parent planet. Under such an explanation, gravity would have caused material in the early solar system to draw together at the same time as gravity bound particles together to form Earth. Such a moon would have a very similar composition to the planet, and would explain the moon’s present location. However, although Earth and the moon share much of the same material, the moon is much less dense than our planet, which would likely not be the case if both started with the same heavy elements at their core.

    Capture theory

    Perhaps Earth’s gravity snagged a passing body, as happened with other moons in the solar system, such as the Martian moons of Phobos and Deimos. Under the capture theory, a rocky body formed elsewhere in the solar system could have been drawn into orbit around the Earth. The capture theory would explain the differences in the composition of the Earth and its moon. However, such orbiters are often oddly shaped, rather than being spherical bodies like the moon. Their paths don’t tend to line up with the ecliptic of their parent planet, also unlike the moon.

    Although the co-formation theory and the capture theory both explain some elements of the existence of the moon, they leave many questions unanswered. At present, the giant impact hypothesis seems to cover many of these questions, making it the best model to fit the scientific evidence for how the moon was created.
    Conceptual illustrations of the birth of the moon.

    m1

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    m3

    m4

    m5

    m6

    See the full article, with video, here.

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  • richardmitnick 6:04 pm on December 20, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From SPACE.com: “Orion’s Belt: String of Stars & Region of Star Birth” 

    space-dot-com logo

    SPACE.com

    December 20, 2014
    Elizabeth Howell

    Orion’s Belt is an asterism of three stars that appear about midway in the constellation Orion the Hunter. The asterism is so called because it appears to form a belt in the hunter’s outfit. It is one of the most famous asterisms used by amateur astronomers. Asterisms are patterns of stars of similar brightness. The stars may be part of a larger constellation or may be formed from stars in different constellations.

    Spotting the belt is actually one of the easiest ways to find the constellation Orion itself, which is among the brightest and most prominent in the winter sky. The three stars that traditionally make up the belt are, from west to east: Mintaka, Alnilam and Alnitak. The names of the outer two both mean “belt” in Arabic, while Alnilam comes from an Arabis word that mean “string of pearls,” which is the name of the whole asterism in Arabic, according to astronomer Jim Kaler.

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    The stars Alnilam, Mintaka and Alnitak form Orion’s belt.
    Credit: Martin Mutti, Astronomical Image Data Archive

    Hanging down from Orion’s Belt is his sword, which is made up of three fainter stars. The central “star” of the sword is actually the Orion Nebula (M42), a famous region of star birth. The Horsehead Nebula (IC 434), which is a swirl of dark dust in front of a bright nebula, is also nearby.

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    In one of the most detailed astronomical images ever produced, NASA/ESA’s Hubble Space Telescope captured an unprecedented look at the Orion Nebula. … This extensive study took 105 Hubble orbits to complete. All imaging instruments aboard the telescope were used simultaneously to study Orion. The Advanced Camera mosaic covers approximately the apparent angular size of the full moon.

    NASA Hubble Telescope
    NASA Hubble schematic
    Hubble

    Looking north of the belt, Orion’s “shoulders” are marked by Betelgeuse and Bellatrix and south, his “knees” are Saiph and Rigel.

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    Skywatcher Per-Magnus Heden wondered if the Vikings gazed at the same starry sky, which includes the constellation Orion at bottom, when he took this photo in Feb. 2011.
    Credit: P-M Hedén/TWAN

    Cultural references and notable features

    “The only real legend that is sometimes referred to in Western Culture with Orion’s Belt is the Three Kings,” said Tom Kerss, an astronomer with the Royal Observatory Greenwich, in a Space.com interview. This is a direct reference to the Biblical tale of the three kings who offered gifts to the Baby Christ shortly after his birth.

    Because Orion’s Belt is so easy to find in the sky, it can be used as a pointer to bring amateur astronomers to other interesting objects. Move northwest of the star complex and eventually the line will bring you to the Pleiades star cluster, a collection of dozens of stars that are sometimes called the Seven Sisters (after those that are the most easily visible to the naked eye.)

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    The Pleiades, an open cluster consisting of approximately 3,000 stars at a distance of 400 light-years (120 parsecs) from Earth in the constellation of Taurus. It is also known as “The Seven Sisters”, or the astronomical designations NGC 1432/35 and M45.

    http://hubblesite.org/newscenter/archive/releases/2004/20/image/a/

    Following southwest of the stars will lead you to Sirius, the brightest star in the sky in both the Northern and Southern hemispheres. Part of its brightness in the sky comes because it is so close to us, just 8.7 light-years away.

    Kerss said the shape is also interesting astronomically. Some of the stars themselves are physically close together (which is not always true of stars in the sky, which only appear to be nearby.)
    Recent astronomical news

    Although the Orion Nebula has been studied thoroughly by both amateur and professional astronomers, surprises continue with further observations.

    In 2013, a Chilean European Southern Observatory telescope spotted signs of a cosmic “ribbon” in the nebula that is more than 1,000 light-years away. The track contains cold gas and dust, and astronomers also noted they may have found 15 young stars or protostars while making these observations.

    Even closer looks at the nebula have revealed features such as this bow shock from the young star LL Ori, which is sending out wind that strikes gas leaving the heart of the star-forming region.

    See the full article here.

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  • richardmitnick 6:09 am on December 20, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From RAS: “Science and Innovation Strategy: RAS Response” 

    Royal Astronomical Society

    Royal Astronomical Society

    Friday, 19 December 2014
    No Writer Credit

    The UK government published its new Science and Innovation strategy on Wednesday 17 December. The new document, “Our Plan for Growth: science and innovation” includes a number of positive announcements and restatements of support for projects in astronomy and geophysics, such as the capital funding for the Square Kilometre Array (SKA) radio observatory and the Polar Research Ship, and the more recent support for the European Space Agency to develop the ExoMars mission.

    SKA Pathfinder Radio Telescope
    SKA Pathfinder telescope

    ESA ExoMars
    ESA/ExoMars

    The Society welcomes these, along with the statement of support for peer review in investment decisions; the importance of international collaboration, the new targets for the recruitment of maths and physics teachers, the new postgraduate loans scheme, the recognition of the success of the Gaia and Rosetta missions and the opportunities presented by Major Tim Peake’s flight to the International Space Station next year.

    ESA Gaia satellite
    ESA/Gaia

    ESA Rosetta spacecraft
    ESA/Rosetta

    More generally, one of the long-standing concerns of the scientific community has been the low level of public (and private) funding for science compared with other EU and OECD countries. The new strategy explicitly addresses this, with a pledge to examine resource spending in the 2015 Spending Review. The Society welcomes this commitment and the overarching statement that policies for science and innovation should not detract from the importance of fundamental research being carried out for its own sake.

    International collaboration, including UK leadership in European scientific programmes such as Horizon 2020, also has a high prominence. The Society endorses this view and the pledge to use the UK presidency of the EU to support this activity.

    The RAS however remains concerned about several fundamental areas, including the lack of commitment to protect the science ‘ring fence’. This flat cash budget has already been eroded significantly since 2010 and even a low inflation environment will have a serious impact on purchasing power in the years ahead. If this policy continues, the inevitable outcome will be a reduction in the resources (not least postgraduate students and postdoctoral researchers) needed to exploit scientific data. This could greatly hinder the UK’s ability to reap the full benefits of the capital investment in scientific projects. And although there is recognition of the need to recruit the most talented people from across the globe, though there seems no prospect of a loosening of the restrictions on immigration that can make such recruitment almost impossible in practice.

    President of the Royal Astronomical Society Prof Martin Barstow commented: “I am delighted to see that the Government so clearly recognises the importance of scientific research, including the ‘blue skies’ sciences that are so important to the RAS and our Fellows and which are so valued by the wider public. There has though been a hollowing out of the resource budget needed to make the most of our involvement and investment in major scientific programmes, something that will need to be tackled if the UK is to remain a world player in research. As RAS President I will be pressing the Government to tackle this in next year’s Spending Review, in order to deliver the secure environment that will allow our researchers to flourish.”

    See the full article here.

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    The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science.

     
  • richardmitnick 10:37 pm on December 19, 2014 Permalink | Reply
    Tags: , , , Astrophysics,   

    From Ethan Siegel: “Dark Matter vs. Dark Energy” 

    Starts with a bang
    Starts with a Bang

    Dec 19, 2014
    Ethan Siegel

    “We are incredibly heedless in the formation of our beliefs, but find ourselves filled with an illicit passion for them when anyone proposed to rob us of their companionship.” -James Harvey Robinson

    Sure, most of us have some version in our heads of how this — the Universe — all came to be the way it is. Yet some of the details, no matter how scientifically well-versed we are, have got to seem puzzling. This week’s Ask Ethan comes courtesy of the inquiry of Tom Anderson, who becomes the fourth winner in our Year In Space 2015 calendar giveaway, with his submission:

    [D]ark matter attracts while dark energy repels. Dark energy is continuously driving the expansion of space in between gravitationally bound galaxies/clusters and it seems that the current general consensus is that universe is set to ever expand, cooling and eventually into a “big freeze” scenario. Taking from this, as gravitationally bound systems do not expand, that the combined attraction force of dark matter and ordinary matter is equal or greater to the repelling force of dark energy and ordinary energy. Why then, did the universe expand at all after the Big Bang? [W]hy didn’t the dark matter counteract the force of the dark energy in the universe’s infancy?

    This is a mouthful, so let’s start by breaking this down.

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    Image credit: wiseGEEK, © 2003–2014Conjecture Corporation, via http://www.wisegeek.com/what-is-cosmology.htm#; original from Shutterstock / DesignUA.

    The way the Universe works, and how structures like stars, galaxies, and clusters of galaxies form is a little bit out of the realm of our ordinary experience. To simplify it greatly, our Universe is made of expanding spacetime, where the rate of expansion starts off at some initial value, determined by the physics of cosmic inflation and how that inflationary period ends.

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    Image credit: Don Dixon / Cosmographica, representing cosmic inflation and its end; original from http://www.cosmographica.com/.

    But that expansion rate isn’t constant once inflation does end, because the Universe is filled with all sorts of other forms of energy: radiation, matter, antimatter, neutrinos, dark matter, and a little bit of energy inherent to space itself, known as dark energy. It’s the combination of all these things — which change as the Universe expands — that determine how the expansion rate of the Universe changes as time goes on.

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    Images credit: Pearson / Addison-Wesley ; Quantum Stories, retrieved via http://cuentos-cuanticos.com/.

    So, on a global scale, meaning on the scale of the entire Universe, it’s either going to recollapse entirely, expand forever, or be right on the border between those two cases, depending on what the varying ratios of all the different forms of energy are in the Universe.

    For the one we actually live in, it looks like the Universe will expand forever and ever, as dark energy has come to dominate our Universe at late times.
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    Image credit: Don Dixon, from Scientific American 15, 66–73 (2006) doi:10.1038/scientificamerican0206–66sp.

    But this analysis doesn’t apply to the Universe on all scales; it simply tells us what is happening to the Universe on a global scale, or the scale of the entire Universe! It tells us that now, at late times and on large scales, objects that are not yet gravitationally bound together will begin accelerating away from one another.

    But there are still gravitationally bound systems, and they exist on small scales in great abundance, on medium scales in moderate abundance, and on relatively large scales in sparse but non-zero abundance. And it’s all part of the same cosmic story.

    You see, the Universe didn’t start off perfectly smooth, with exactly equal amounts of matter, radiation, dark matter and dark energy in all locations. If it had, our Universe would be incredibly boring; it would be a perfectly uniform sea where everyplace was exactly average. There would be no stars, galaxies or planets, no voids or places that were empty, no people, animals, life, clusters or filaments.

    Instead, from a very early time, we find that the Universe has slight regions of overdense and underdense regions on all scales: on small, medium and large scales.

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    A cosmological simulation of dark matter growing clumpier over time. Image credit: Andrey Kravtsov.

    Dark matter helps the overdense regions grow over time, and they can grow quickly enough that they will gravitationally collapse, in as little as a few tens of millions of years. It’s as though small regions of the Universe started out, locally, with an overall matter-and-energy density that was great enough so that, if the entire Universe were that way, it would have recollapsed altogether rather quickly!

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    Ned Wright’s Cosmology tutorial, via http://www.astro.ucla.edu/~wright/cosmo_03.htm

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    Ross Church of Jesus College, via http://jcsu.jesus.cam.ac.uk/

    Of course, there are many more regions where the density is less than average, and they tend to give up their matter to the denser regions; if the entire Universe were like those regions, we would have very, very few stars, galaxies and clusters.

    But it’s this very diversity in initial conditions all over the Universe that enables us to wind up with this huge diversity of all that we can see. In the cosmic struggle of dark matter vs. dark energy, of gravitation vs. the expansion, of the great cosmic “pulls” to form structure and the cosmic “pushes” to suppress it, there are both winners and losers.

    We notice the winners far more easily, because they copiously emit and absorb visible light and light from other portions of the electromagnetic spectrum, they gravitationally lens material behind them, and because it’s a lot easier to detect the presence rather than the absence of something.

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    Image credit: NASA; ESA; G. Illingworth, UCO/Lick Observatory and the University of California, Santa Cruz; R. Bouwens, UCO/Lick Observatory and Leiden University; and the HUDF09 Team.

    But the empty regions are there, and they matter, and — in fact — they vastly outnumber the “full” regions! The combined attractive force of dark and normal matter can defeat both the initial expansion and the additional, accelerative force of dark energy, but only on relatively small scales and at relatively early times.

    As we go to larger and larger scales, we find that there are more and more victories for repulsion, and as we reach the largest scales, repulsion always wins.

    The Universe expanded in the beginning because of the initial conditions set up by inflation, and the recollapse option — thanks to the gravitational pull of quantities like normal matter, dark matter, radiation and neutrinos — was only enough to “win” in a few select locations. It didn’t win in all of them, it didn’t win in most of them, and it didn’t win on average.

    And that’s why, when we look out at our Universe today, there are tons of galaxies littered throughout it, many of them clustered together in groups and large collections, and on large scales, aligned along filaments. But these galaxy groups that consist of a few thousand galaxies spanning a few hundred million light-years in size are most likely the largest bound structures we have; on all scales larger than that, alignments are temporary, as the presence of dark energy will eventually drive them apart.

    If the Universe had just the tiniest amount more of dark matter — something like 1 part in 10^24 more — it would have recollapsed billions of years ago. It was very finely balanced for a long time — with gravity winning locally in some spots and losing in others — but now that dark energy has come to dominate it, we’re seeing that its effects are going to win out. It wins in the end, it wins on the largest scales, and it wins for everything that wasn’t already gravitationally bound together after the first seven-or-so billion years of the Universe.

    And that, Tom Anderson, is the answer to your question about the growth, expansion and fate of the Universe! We only have one week left (and one more calendar left) for our Year In Space 2015 calendar giveaway, and if you want a chance to win it, send in (along with your email address) your questions or suggestions for an Ask Ethan column. You could be the year’s final lucky winner!

    See the full article, with video, here.

    Please help promote STEM in your local schools.

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    Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible.

     
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