Tagged: Astrophysics Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 10:17 am on November 23, 2014 Permalink | Reply
    Tags: , Astrophysics, , , ,   

    From Ethan Siegel:- “Ask Ethan #63: The Birth of Space and Time” 

    Starts with a bang
    Starts with a Bang

    Nov 22, 2014
    Ethan Siegel

    If there’s something before the Big Bang, then what does that mean for the beginning of our Universe?

    “You can try to lie to yourself. You can try to tell yourself that you put in the time. But you know — and so do I.” -J.J. Watt

    It’s been half a century since the greatest new predictions of the Big Bang were confirmed, changing our conception of the Universe forever. Rather than having existed forever, and rather than the part accessible to us being infinite in extent, we now know that all we perceive has only been around for a hair under 14 billion years of cosmic time, with our Sun and Solar System present for merely the last third of it. Which is what makes today’s Ask Ethan question so interesting, courtesy of Sebastián:

    When did the space-time begin? When I was a child, I learned that the Big Bang was the beginning of everything. I guess this picture is not currently true, since before [?] the Big Bang there was the cosmic inflation, and the Big Bang was not even a bang but a state where the Universe was hotter and denser. If there was inflation before the Big Bang, then there was space-time before the Big Bang, right?

    There are three things we need to think about to fully address Sebastián’s question, and the first one is what we mean by space and time.

    f
    Image credit: Firefly / Serenity.

    You may be used to our everyday experiences of space — notions like length, width and depth — and time, which you might simply think of as the answers to the questions of where and when. This actually isn’t such a bad conception of things, but there are two things you need to know about space and time that might be a little bit less than intuitive. In fact, it literally took an [Albert] Einstein to figure it all out, and even he needed some help!

    The first is that space and time weren’t separable notions, as [Isaac] Newton thought they were. If you move through space, it fundamentally changes how time passes for you, and if two people move through space at different rates relative to one another, the way they experience time for themselves and the way they see time passing for the other person will be different from one another.

    i
    Image credit: John D. Norton of Pittsburgh, via http://www.pitt.edu/~jdnorton/teaching/HPS_0410/chapters/Special_relativity_clocks_rods/index.html.

    The way this makes the most sense — and it wasn’t Einstein who figured this out, but rather the mathematician Hermann Minkowski — is to consider a unified concept of spacetime, where instead of three spatial dimensions and one time dimension, we consider a new four dimensional entity known as spacetime. Speaking in 1908, Minkowski put forth the idea:

    The views of space and time which I wish to lay before you have sprung from the soil of experimental physics, and therein lies their strength. They are radical. Henceforth space by itself, and time by itself, are doomed to fade away into mere shadows, and only a kind of union of the two will preserve an independent reality.

    Although Einstein was initially resistant to this revolution, his eventual acceptance of it led to an even greater revelation.

    s
    Image credit: NASA, ESA, L. Calcada.

    The idea that not only were space and time connected into a unified 4D fabric, spacetime, but that the curvature of this 4D fabric was caused by the presence of matter and energy! Just as motion through spacetime affected how different observers experience the passage of time and the distances of space, the presence of matter and energy (and of curvature in general) affects the experience of space and time, too.

    And in the most extreme examples of concentrations of matter and energy — into a singularity — notions of space and time break down!

    c
    Image credit: © Astronomical Society of the Pacific.

    Our most common conceptions of singularities are at the centers of black holes, where we achieve an arbitrarily large (and possibly infinite) density of matter and energy at a single point. In this case, our conception of spacetime breaks down, as Einstein’s equations give nonsensical results.

    Which brings up the second thing we need to think of: the framework of the Big Bang!

    k
    Image credit: NASA, ESA, the GOODS team and M. Giavalisco (STScI); Hubble Space Telescope.

    NASA Hubble Telescope
    NASA Hubble schematic
    NASA/ESA Hubble

    We think of the Universe as being a relatively cold, empty place today, save for the dense concentrations of matter, stars, planets and life that have formed over the billions of years the Universe has been around. Thanks to gravity, electromagnetism and the [strong and weak]nuclear forces, we’ve built up this towering cosmic structure that ranges from the subatomic scale all the way up to tremendous clusters of galaxies.

    But if we go back in time, we discover that not only were things more gravitationally uniform in the past, but also that our cooling, expanding Universe was hotter (since wavelengths of light were shorter) and denser, all due to the nature of the way spacetime expands.

    n
    Image credit: Take 27 LTD / Science Photo Library (main); Chaisson & McMillan (inset).

    We can go as far back in time as we like, to the earliest stages imaginable, to ever higher energies, hotter temperatures and increasing densities. We can go back to:

    A time before any stars or galaxies formed, to when the Universe was just a sea of warm, neutral atoms.
    A time when it was too hot to form neutral atoms at all, when the Universe was just an ionized plasma of nuclei and electrons.
    A time when it was too hot to even form simple nuclei, as free protons and neutrons (along with electrons and photons) reigned.
    A time when densities and temperatures were so high that particle collisions routinely and spontaneously created matter/antimatter pairs of all the known particles in the Universe.

    And you might think to go even further than that, to an arbitrary high density, high temperature and to an “event” in spacetime that also corresponds to a singularity: a moment where the entire Universe is concentrated into a single point.

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

    If this were the case, this is exactly where space and time began, as there’s no such thing as “where” outside of space, and no such thing as “when” outside of time. But there would have been a myriad of puzzles that were simply unexplained about our Universe if we accepted this as the true beginning, as we now have physics that teaches us that we can’t go arbitrarily far back, but rather that a state of inflation — of an exponentially expanding spacetime with energy inherent to space itself — preceded and led to the hot, dense expanding state that we identify with the Big Bang.

    l
    Image credit: ESA and the Planck collaboration, modified by me.

    Because the moment that energy, all bound up in space itself, gets converted into matter and radiation, the exponential expansion ends, and gives us a Universe that appears just as we conceive our early Universe to have been.

    m
    Image generated by me. Each “X” represents a region where inflation ends and a Universe like ours is born; each box without one continues to inflate. At all times into the future, there are more boxes without “X”s than with one. But it does go arbitrarily far back to the past, with no “beginning” to spacetime.

    But now that leads to the third and final point, keeping our notions of singularities in spacetime and the Big Bang in mind: if the Universe before the Big Bang — back during inflation — consisted of exponentially expanding spacetime, where did that spacetime come from?

    As crazy as it seems, there are three very intuitive options.

    The Universe could have had a beginning, before which nothing existed.
    It could have existed eternally, like an infinite line extending in both directions.
    It could have been cyclic like the circumference of a circle, repeating over and over again infinitely.

    h
    Image credit: me.

    If we went with the old Big Bang (and no inflation) picture, the evidence would favor option 1: the Universe being born at the “moment” of infinite, arbitrarily high energies, and along with it, the birth of spacetime.

    However, inflation changes that tremendously. It tells us that rather than a singularity at “t=0”, or where the Big Bang occurred, it tells us that the Universe existed in an inflationary state, or a state where it was exponentially expanding, for an indeterminately long amount of time.

    o
    x
    Images credit: me. Blue and red lines represent a “traditional” Big Bang scenario, where everything starts at time t=0, including spacetime itself. But in an inflationary scenario (yellow), we never reach a singularity, where space goes to a singular state; instead, it can only get arbitrarily small in the past, while time continues to go backwards forever.

    So it appears to favor option 2: the Universe being eternal to the past.

    But there’s a catch to even that, as it turns out. There is a theorem that tells us that an inflationary Universe is past-timelike incomplete: that an ever-expanding Universe must have began from a singularity.

    g
    Image credit: Cosmic Inflation by Don Dixon.

    But that may not be fair, in the sense that the theorem is based on the known laws of physics, and applying them to a time when the known laws of physics break down. Furthermore, as huge and full-of-stuff as our Universe is, the amount of material (and hence, information) in it is still not infinite! With some ~10^90 particles (including photons and neutrinos), going back all the way to the hot, dense expanding state of the Big Bang and then some 10^-30 seconds before to the last moments of inflation, there are some things that are still observationally inaccessible to us.

    d
    Image credit: Bock et al. (2006, astro-ph/0604101); modifications by me.

    Unfortunately, one of those things is where that inflating spacetime came from!

    Whether all this means that an inflating Universe couldn’t have lasted forever or whether that means our current rules of physics are not applicable to figuring out whether it lasted forever, had a beginning or is cyclical are unknown. It’s even possible that time is cyclical, and that the cycles change with each iteration! For all our progress, we still have the same three options that philosophers and theologians have considered for millennia: time is finite, time is infinite, or time is cyclical.

    j
    Image credit: me.

    The only thing we know is that if there was a singularity in the past, it didn’t have anything to do with our Hot Big Bang that every particle of matter-and-energy in our observable Universe is traceable to.

    And unless we figure out a new way to gain information about what happened before the Universe observable to us existed in any meaningful sense, the answer may forever be beyond the reach of what is knowable. Not every Ask Ethan question is going to have a definitive answer, but rather this is the best we know given our current body of knowledge. I’m pleased to announce that the next five Ask Ethan questions that are chosen will also be the winner of a free holiday giveaway (to be announced tomorrow), so don’t just send in your questions and suggestions here, but also let me know how to contact you, in case you’re one of the lucky winners!

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

     
  • richardmitnick 1:44 pm on November 22, 2014 Permalink | Reply
    Tags: , Astrophysics, , , ,   

    From SPACE.com: “How Many Stars Are in the Milky Way?” 

    space-dot-com logo

    SPACE.com

    May 21, 2014
    Elizabeth Howell

    “Billions and billions” of stars in a galaxy (after a quote often mistakenly attributed to Carl Sagan) is how many people imagine the number of stars you would find in one. Is there any way to know the answer for sure?

    s
    Night sky photographer Amit Ashok Kamble captured this amazing panorama of the Milky Way over Pakiri Beach, New Zealand by stitching 10 images together into a complete mosaic. Image submitted May 5, 2014.Credit: Amit Ashok Kamble

    “It’s a surprisingly difficult question to answer. You can’t just sit around and count stars, generally, in a galaxy,” said David Kornreich, an assistant professor at Ithaca College in New York State. He was the founder of the “Ask An Astronomer” service at Cornell University.

    Even in the Andromeda Galaxy — which is bright, large and relatively close by Earth, at 2.3 million light-years away — only the largest stars and a few variable stars (notably Cepheid variables) are bright enough to shine in telescopes from that distance. A sun-size star would be too difficult for us to see. So astronomers estimate, using some of the techniques below.

    pup
    This Hubble image shows RS Puppis, a type of variable star known as a Cepheid variable. As variable stars go, Cepheids have comparatively long periods— RS Puppis, for example, varies in brightness by almost a factor of five every 40 or so days. RS Puppis is unusual; this variable star is shrouded by thick, dark clouds of dust enabling a phenomenon known as a light echo to be shown with stunning clarity. These Hubble observations show the ethereal object embedded in its dusty environment, set against a dark sky filled with background galaxies.

    an
    Andromeda Galaxy
    The Andromeda Galaxy is a spiral galaxy approximately 2.5 million light-years away in the constellation Andromeda. The image also shows Messier 32 and Messier 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.
    18 September 2010
    Adam Evans

    Massive investigation

    The primary way astronomers estimate stars in a galaxy is by determining the galaxy’s mass. The mass is estimated by looking at how the galaxy rotates, as well as its spectrum using spectroscopy.

    All galaxies are moving away from each other, and their light is shifted to the red end of the spectrum because this stretches out the light’s wavelengths. This is called “redshift.” In a rotating galaxy, however, there will be a portion that is more “blueshifted” because that portion is slightly moving toward Earth. Astronomers must also know what the inclination or orientation of the galaxy is before making an estimate, which is sometimes simply an “educated guess,” Kornreich said.

    A technique called “long-slit spectroscopy” is best for performing this type of work. Here, an elongated object such as a galaxy is viewed through an elongated slit, and the light is refracted using a device such as a prism. This breaks out the colors of the stars into the colors of the rainbow.

    Some of those colors will be missing, displaying the same “patterns” of missing portions as certain elements of the periodic table. This lets astronomers figure out what elements are in the stars. Each type of star has a unique chemical fingerprint that would show up in telescopes. (This is the basis of the OBAFGKM sequence astronomers use to distinguish between types of stars.)

    PeriodicTable
    Periodic Table of elements

    Any kind of telescope can do this sort of spectroscopy work. Kornreich often uses the 200-inch telescope [Hale] at the Palomar Observatory at the California Institute of Technology, but he added that almost any telescope of sufficient size would be adequate.

    Caltech Palomar Observatory
    Caltech Hale Telescope at Palomar
    Hale Telescope at Palomar

    The ideal would be using a telescope in orbit because scattering occurs in Earth’s atmosphere from light pollution and also from natural events — even something as simple as a sunset. The Hubble Space Telescope is one observatory known for this sort of work, Kornreich added.

    NASA Hubble Telescope
    NASA Hubble schematic
    NASA/ESA Hubble

    How much of the mass is stars?

    Between different galaxies of the same mass, there could be variances as to the types of stars and the overall mass. Kornreich cautioned this would be very hard to speak about generally, but said that one difference could be looking at elliptical galaxies vs. spiral galaxies such as our own, the Milky Way. Elliptical galaxies tend to have more K- and M-type red dwarf stars than spiral galaxies, and because they are older, will have less gas because that was blown away during their evolution.

    Once a galaxy’s mass is determined, the other tricky thing is figuring out how much of that mass is stars. Most of the mass will be made up of dark matter, which is a mysterious substance believed to bind most of the universe together.

    “You have to model the galaxy and see if you can understand what the percentage of that mass of stars is,” Kornreich said. “In a typical galaxy, if you measure its mass by looking at the rotation curve, about 90 percent of that is dark matter.”

    With much of the remaining “stuff” in the galaxy made up of diffuse gas and dust, Kornreich estimated that about 3 percent of the galaxy’s mass will be made up of stars, but that could vary. Further, the size of the stars itself can greatly vary from something that is the size of our sun, to something dozens of times smaller or bigger.

    The number of stars is approximately …

    So is there any way to figure out how many stars are for sure? In the end, it comes down to an estimate. In one calculation, the Milky Way has a mass of about 100 billion solar masses, so it is easiest to translate that to 100 billion stars. This accounts for the stars that would be bigger or smaller than our sun, and averages them out. Other mass estimates bring the number up to 400 billion.

    The caveat, Kornreich said, is that these numbers are approximations. More advanced models can make the approximation more accurate, but it would be very difficult to count the stars one by one and tell you for sure how many are in the galaxy.

    Correction: This article was updated at 4 p.m. May 21 to include a more accurate estimation of the number of stars in the Milky Way.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

     
  • richardmitnick 4:09 pm on November 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From NASA/SOFIA: “SOFIA Observations Help Determine the Age of a Star Nursery” 

    NASA SOFIA Banner

    SOFIA (Stratospheric Observatory For Infrared Astronomy)

    An international scientific team led by scientists of the Coordinated Research Center (CRC) 956 at the University of Cologne, Germany, applied a new method of age determination to a combination of data from SOFIA and other observatories to make a surprising discovery: The star forming cloud IRAS 16293-2422, located at a distance of about 400 light years in the direction of the constellation Ophiuchus, is at least 1 million years old yet is still making sun-like stars. This is in conflict with current models, which predict star formation should proceed much more rapidly. That result is published in this week’s volume of Nature magazine by researchers from Cologne plus the University of Helsinki and the Max Planck Institutes for Radio Astronomy (MPIfR; Bonn) and Extraterrestrial Physics (MPE; Garching).

    Stars like our sun and their planetary systems form from cold and dense interstellar gas and dust clouds that collapse under their own weight. In the first step the material condenses into stellar “embryos” called protostars. Details of how such condensations occur, and on what timescales, are not very well understood. For example, do the clouds “free-fall” toward their respective centers solely under the influence of gravity, or is the collapse significantly slowed by other factors? “Since this process takes much longer than human history, it cannot just be followed as a function of time. Instead, one needs to find an internal clock that allows us to read off the age of a particular star forming cloud,” says lead author Sandra Brünken.

    s
    The GREAT far-infrared spectrometer onboard SOFIA. The instrument is
    shown mounted on the telescope flange inside the pressurized cabin.
    © R. Güsten

    Here is where SOFIA flies in to help: The molecule H 2D + (a combination or two atoms of ordinary ‘ light’ hydrogen plus one atom of ‘heavy’ hydrogen, deuterium) is enriched in dense and cold star forming regions. The spin axes of the two H atom nuclei within each molecule flip their relative orientations at a known rate. Molecules with one nuclear spin orientation emit and absorb a spectral line at a far-infrared wavelength of 219 microns (1.37 THz, ‘para’ state, anti-parallel spins). Molecules with the opposite spin emit and absorb at a radio wavelength of 0.806 millimeters (372 GHz, ‘ortho’ state, parallel spins). Because Earth’s atmosphere absorbs all far-infrared radiation from celestial sources, the only observatory able to detect the 219-micron line is SOFIA, operating at an altitude of about 14 km, carrying the GREAT (German Receiver for Astronomy at THz Frequencies) spectrometer. Another advantage is that – in contrast to satellites – the newest technology could be implemented on SOFIA on short time scales; until recently, no instrument was available that could detect the critical range of wavelength for this study. Complementary observations of the millimeter-wavelength line were obtained using the ground-based APEX (Atacama Pathfinder EXperiment) telescope located in the Chilean Andes at an altitude of 5100 meters (16,700 feet). In their Nature publication the team around Stephan Schlemmer at the University of Cologne explains why the ratio of the ortho (APEX) to para (SOFIA) states of H 2D + in cold and dense gas clouds allows an accurate age estimation of Sun-like star nursery. Reading this chemical clock for IRAS 16293-2422 yields an age of at least 1 Million years.

    ESO APEX
    ESO/APEX

    “These H 2D + measurements introduce a basic new method for age determinations in cold molecular clouds, with SOFIA’s far infrared spectroscopy capable of playing a major role” , comments Hans Zinnecker from the German SOFIA Institute (DSI) at the University of Stuttgart, who is Deputy Director of SOFIAs Science Mission Operations located at NASA’s Ames Research Center, Moffett Field, Calif. “This underlines the future potential of SOFIA, since at the moment the NASA/DLR airborne observatory is the only one that allows astronomers to detect far infrared radiation from the cosmos.”

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    SOFIA is a joint program of NASA and the German Aerospace Center (DLR), and is based and managed at NASA’s Dryden Aircraft Operations Facility in Palmdale, Calif. NASA’s Ames Research Center in Moffett Field, Calif., manages the SOFIA science and mission operations in cooperation with the Universities Space Research Association (USRA), headquartered in Columbia, Md., and the German SOFIA Institute (DSI) at the University of Stuttgart.

    NASA

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 3:12 pm on November 21, 2014 Permalink | Reply
    Tags: , , , , Astrophysics,   

    From IceCube: “Neutrino, measuring the unexpected” 

    icecube
    IceCube South Pole Neutrino Observatory

    Francis Halzen, IceCube Principal Investigator, explains the search for high-energy neutrinos in this three party story of neutrinos. Produced by IFIC, Directed by Javier Diez. [Sorry, I cannot come up with Parts 1 and 3. But this video stands on its own merit.]

    Watch, enjoy. learn.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 2:58 pm on November 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , Binaries, ,   

    From Space.com: “Binary Earth-Size Planets Possible Around Distant Stars” 

    space-dot-com logo

    SPACE.com

    November 21, 2014
    Charles Q. Choi

    Two Earth-size planets that orbit each other might exist around distant stars, researchers say.

    2
    Artist’s concept depicting an imminent planetary collision around a pair of double stars.
    Credit: NASA/JPL-Caltech

    The solar system has many examples of moons orbiting planets; Jupiter and Saturn both possess more than 60 satellites. However, these moons are usually much smaller than their planets — Earth is nearly four times wider than its moon and more than 80 times its mass.

    Still, some moons are as large as planets. For instance, Ganymede, Jupiter’s largest moon, is larger than Mercury, and three-quarters the diameter of Mars. Also, moons at times are nearly as large as their worlds; Pluto’s largest moon, Charon, is about half the diameter of the dwarf planet itself. This raises the intriguing possibility that planets of equal size could orbit each other.

    Binary stars, or two stars orbiting each other, are very common throughout the Milky Way galaxy. Some of these two-star systems are even known to host exoplanets — worlds with two suns, like Luke Skywalker’s home planet of Tatooine in Star Wars. Binary asteroids also exist in the solar system. However, binary or double planets involving Earth-size worlds are currently only science fiction.

    One possible way that binary planets might form is when two worlds orbiting a star get close enough to one another to interact gravitationally. To see if these systems are possible, researchers simulated two rocky Earth-sized planets veering toward each other. They modeled each world as made up of 10,000 particles and varied the speed of the planets and the angles of their approaches. The scientists managed to simplify their models so that each simulation took as little as a day to run instead of up to a week as they did at the beginning of their work.

    The scientists ran about two dozen simulations. However, these simulations often resulted in the planets colliding, typically merging or accreting together into a larger planet and sometimes leaving behind a disk of debris from which a moon could form. Also, in some simulations, the planets collided in a grazing manner at high speeds, resulting in “hit and run” interactions in which the worlds escaped from one another.

    Still, about one-third of the simulations resulted in binary planets forming. These involved relatively slow, grazing collisions.

    “Previously, the only expected outcomes of large-body impacts of this sort were escape or accretion — that is, either the two bodies do not stay together or they merge into one, occasionally with a disk of debris,” study co-author Keegan Ryan, an undergraduate student at the California Institute of Technology in Pasadena, told Space.com. “Our findings suggest the possibility of another outcome — binary planets. The bodies stay mostly intact, but end in a bound orbit with one another.”

    These binary planets would loom extraordinarily close to one another, separated by a distance of about half the diameter of each of the worlds. Over time, the rate at which both planets spin would fall into lockstep, with each world only turning one face toward its partner.

    Such binaries can persist for billions of years, researchers say, provided they form at least half an astronomical unit or more away from their parent stars — far enough away for the star’s gravitational pull to not disrupt the binary planet system. (One astronomical unit, or AU, is the average distance between the sun and Earth, about 93 million miles, or 150 million kilometers.)

    The research team’s goal from here “is to run more simulations, increase the parameters of the simulations, and work to get a better picture of the probability that a binary planet might form,” Ryan said.

    Ryan and his colleagues Miki Nakajima and David Stevenson detailed their findings Nov. 11 at the American Astronomical Society’s Division for Planetary Sciences meeting in Tucson, Arizona.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 2:32 pm on November 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , ,   

    From phys.org: “It’s filamentary: How galaxies evolve in the cosmic web” 

    physdotorg
    phys.org

    Nov 20, 2014
    Provided by University of California – Riverside

    How do galaxies like our Milky Way form, and just how do they evolve? Are galaxies affected by their surrounding environment? An international team of researchers, led by astronomers at the University of California, Riverside, proposes some answers.

    web
    Galaxies are distributed along a cosmic web in the universe. “Mpc/h” is a unit of galactic distance (1 Mpc/h is more than 3.2 million light-years). Credit: Volker Springel, Virgo Consortium

    The researchers highlight the role of the “cosmic web” – a large-scale web-like structure comprised of galaxies – on the evolution of galaxies that took place in the distant universe, a few billion years after the Big Bang. In their paper, published Nov. 20 in the Astrophysical Journal, they present observations showing that thread-like “filaments” in the cosmic web played an important role in this evolution.

    “We think the cosmic web, dominated by dark matter, formed very early in the history of the universe, starting with small initial fluctuations in the primordial universe,” said Behnam Darvish, a Ph.D. graduate student in the Department of Physics and Astronomy at UC Riverside, who led the research project and is the first author on the paper. “Such a ‘skeletal’ universe must have played, in principle, a role in galaxy formation and evolution, but this was incredibly hard to study and understand until recently.”

    The distribution of galaxies and matter in the universe is non-random. Galaxies are organized, even today, in a manner resembling an enormous network – the cosmic web. This web has dense regions made up of galaxy clusters and groups, sparsely populated regions devoid of galaxies, as well as the filaments that link overdense regions.

    “The filaments are like bridges connecting the denser regions in the cosmic web,” Darvish explained. “Imagine threads woven into the web.”

    It is well known in astronomy that galaxies residing in less dense regions have higher probability of actively forming stars (much like our Milky Way), while galaxies in denser regions form stars at a much lower rate.

    “But the role of intermediate environments and, in particular, the role of filaments and the cosmic web in the early universe remained, until very recently, a mystery,” said coauthor Bahram Mobasher, a professor of physics and astronomy at UCR and Darvish’s adviser.

    What greatly assisted the researchers is a giant section of the cosmic web first revealed in two big cosmological surveys (COSMOS and HiZELS). They proceeded to explore data also from several telescopes (Hubble, VLT, UKIRT and Subaru). They then applied a new computational method to identify the filaments, which, in turn, helped them study the role of the cosmic web.

    NASA Hubble Telescope
    NASA/ESA Hubble

    ESO VLT Interferometer
    ESO/VLT

    United Kingdom Infrared Telescope Exterior
    UKIRT

    NAOJ Subaru Telescope
    NAOJ/Subaru

    They found that galaxies residing in the cosmic web/filaments have a much higher chance of actively forming stars. In other words, in the distant universe, galaxy evolution seems to have been accelerated in the filaments.

    “It is possible that such filaments ‘pre-process’ galaxies, accelerating their evolution while also funneling them towards clusters, where they are fully processed by the dense environment of clusters and likely end up as dead galaxies,” Darvish said. “Our results also show that such enhancement/acceleration is likely due to galaxy-galaxy interactions in the filaments.”

    Because of the complexities involved in quantifying the cosmic web, astronomers usually limit the study of the cosmic web to numerical simulations and observations in our local universe. However, in this new study, the researchers focused their work on the distant universe – when the universe was approximately half its present age.

    “We were surprised by the crucial role the filaments play in galaxy formation and evolution,” Mobasher said. “Star formation is enhanced in them. The filaments likely increase the chance of gravitational interaction between galaxies, which, in turn, results in this star-formation enhancement. There is evidence in our local universe that this process in filaments also continues to occur at the present time.”

    Darvish and Mobasher were joined in this research by L. V. Sales at UCR; David Sobral at the Universidade de Lisboa, Portugal; N. Z. Scoville at the California Institute of Technology; P. Best at the Royal Observatory of Ediburgh, United Kingdom; and I. Smail at Durham University, United Kingdom.

    Next, the team plans to extend this study to other epochs in the age of the universe to study the role of the cosmic web/filaments in galaxy formation and evolution across cosmic time.

    “This will be a fundamental piece of the puzzle in order to understand how galaxies form and evolve as a whole,” Sobral said.

    See the full article, with video, here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    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.

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 10:32 am on November 21, 2014 Permalink | Reply
    Tags: , , , , Astrophysics,   

    From Huff Post: “NASA Is Building a Sustainable ‘Highway’ for Unprecedented Deep Space Exploration” 

    Huffington Post
    The Huffington Post

    11/20/2014
    Dan Dumbacher

    In early December, NASA will take an important step into the future with the first flight test of the Orion spacecraft — the first vehicle in history capable of taking humans to multiple destinations in deep space. And while this launch is an un-crewed test, it will be the first peek at how NASA has revamped itself since the end of the Space Shuttle Program in 2011.

    NASA Orion Spacecraft
    NASA/Orion

    While the space shuttle achieved many ground-breaking accomplishments, it was limited to flights in low-Earth orbit (approx. 250 miles high). Its major goal, over the program’s last 10 years, was to launch and assemble the International Space Station, where the risks and challenges of long duration human space flight can be addressed and retired. With the ISS construction complete, NASA is in the process of handing over supply and crew transportation missions to private industry, so NASA can focus on what’s next – deep space exploration. And this first flight test of Orion is a significant milestone on the path to get us there.

    The flight itself will be challenging. Orion will fly 3,600 miles above Earth on a 4.5-hour mission to test many of the systems necessary for future human missions into deep space. After two orbits, Orion will re-enter Earth’s atmosphere at almost 20,000 miles per hour, reaching temperatures near 4,000 degrees Fahrenheit, before its parachute system deploys to slow the spacecraft for a splashdown in the Pacific Ocean.

    While this launch is an important step to taking humans farther than we’ve ever gone before, it is important to note that it also reflects the fact that, after 30 years of space shuttle missions dominating its human spaceflight activities, NASA has reevaluated everything – from its rockets and launch facilities to how it designs and manages its programs. NASA has now infused innovation and flexibility into everything it does.

    With the Orion spacecraft, NASA wanted to develop a vehicle that could fly for decades with the flexibility to visit different destinations and safely return astronauts to Earth as the nation’s exploration goals evolve. As capable as the Apollo capsule was, the longest round trip mission to the Moon took 12 days. Orion is designed as a long-duration spacecraft that will allow us to undertake human missions to Mars – a two year round trip. In addition, NASA built enough capability into Orion so there is no need for redesign, or to start up a new program, as new destinations are identified.

    Innovation and flexibility are also evident with the ground infrastructure. At Kennedy Space Center (KSC) in Florida, NASA has eliminated the ground systems and launch pads that were built specifically for the space shuttle. They have developed a “clean pad” approach that can be used by a variety of launch vehicles. The new streamlined infrastructure will be much more cost-efficient, reducing the time for on-the-pad processing from 30 days, the space shuttle’s timeline, to just five to six days.

    The key to launching Orion on deep space exploration missions is NASA’s new “super rocket.” Known as the Space Launch System (SLS), it will be the most powerful rocket in history. The enormous power of the SLS will provide the capability to go farther into our solar system than humans have ever gone before. It will enable launches to other planets in less than half the time of any existing rocket. And, like Orion and the new ground systems at KSC, it is designed to be flexible and evolvable to meet a wide variety of crew and cargo mission requirements.

    The SLS is an absolute game-changer for ambitious robotic missions to the outer planets and large unprecedented astronomical observatories. Those missions will build on the discoveries of Curiosity on Mars, the Hubble Space Telescope and its successor, the James Webb Space Telescope, and multiple robotic missions in the years ahead.

    NASA Mars Curiosity Rover
    Curiosity

    NASA Hubble Telescope
    NASA/ESA Hubble

    NASA Webb Telescope
    NASA/Webb

    Through the development of the SLS and Orion, NASA has learned many lessons on how to streamline the design to make it more affordable than past systems. For the early missions, SLS will use heritage space shuttle hardware for the liquid engines and solid rocket boosters. Also, instead of initially building the “full-up” SLS, NASA has designed it to evolve by planning upgraded upper stages and boosters that future missions will require in the 2020′s and 2030′s. These innovations have allowed SLS to stay on a relatively flat budget throughout its design phase.

    Even the way NASA manages its programs has been revamped. The Agency’s management structure for systems engineering and integration has been streamlined to increase communication and enhance decision-making. Strong communication has led to increased precision, and the potential cost avoidance is close to $100 million per year. Evidence of these savings can be seen in the successful completions of Preliminary Design Reviews for Orion, SLS and KSC ground systems.

    As a nation, the U.S. has not sent crews beyond low Earth orbit since the last Apollo crew walked on the Moon in 1972. With Orion and SLS, America will have the fundamental capabilities to support missions taking the next steps into deep space, and with innovation and flexibility at the foundation of these programs, NASA is literally building a “Highway” for deep space exploration that will be sustainable for decades to come.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
    • jasper2489 11:19 am on November 21, 2014 Permalink | Reply

      Reblogged this on On The First Page and commented:
      This is exciting. I hope this project actually does what NASA says it will. It means we may be finally taking space exploration more seriously.

      Like

  • richardmitnick 10:16 am on November 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , , ,   

    From Ethan Siegel: “Seeing Through Our Galaxy” 

    Starts with a bang
    Starts with a Bang

    Nov 20, 2014
    Ethan Siegel

    “I am undecided whether or not the Milky Way is but one of countless others all of which form an entire system. Perhaps the light from these infinitely distant galaxies is so faint that we cannot see them.”
    -Johann Lambert

    When we look out at the Universe, our view is pretty consistently dominated by the stars within our own galaxy. Although we know that many interesting things lie beyond — globular clusters, individual galaxies, and rich clusters and superclusters of galaxies — being in the Milky Way makes it very hard to see a great many of them. This is because our own galaxy, from our vantage point within it, dominates a huge fraction of the sky overhead.

    1
    Image credit: Richard Payne, of Arizona Astrophotography.

    The plane of the Milky Way itself obscures about a total of 20% of our night sky. What appears to be a white streak is actually the light from billions upon billions of stars whose light appears to blend together from our point of view, while the dark nebulae are actually neutral clouds of gas-and-dust that appear in the foreground, blocking the light that comes from behind.

    At least in the wavelengths of light visible to our own eyes, this is an incredibly severe effect.

    2
    Image credit: GigaGalaxyZoom, via the European Southern Observatory.

    For a long time, the plane of our galaxy prevented us from seeing very much of anything that lay beyond it. Termed the Zone of Avoidance, searches for distant galaxies and nebulae turned up very few results in this 20% of the sky, while our discoveries elsewhere simply grew and grew. While we were discovering a plethora of objects beyond the galaxy in all other directions, surveying the portion of the night sky that was blocked by our own galaxy was prohibitive. The light-blocking power of the intervening matter — known as extinction — was simply too much to overcome.

    And this would still be true coming all the way up to today if we confined ourselves to the light that our own eyes can see. Thankfully, however, we now know better.

    3
    Image credit: E. L. Wright (UCLA), The COBE Project, DIRBE, NASA, via http://apod.nasa.gov/apod/ap000130.html.

    NASA COBE
    NASA/COBE

    The inset image was the very first picture of the entire sky taken in the infrared, thanks to the COBE satellite’s DIRBE instrument. (And yes, the “IR” in DIRBE stands for infrared.) The final results from COBE led to the main image, where many more stars are visible. You’ll note that the light-blocking effects are tremendously reduced, which is a function of the fact that the “dust” that blocks visible light are actually particles of a certain size, and that size is much less efficient at blocking the longer-wavelength infrared light!

    An even sharper view — in more wavelengths — has been provided by the two-micron all-sky survey (2MASS), as you can see below.

    5
    Image credit: 2MASS / J. Carpenter, T. H. Jarrett, & R. Hurt.

    2MASS Telescope
    2MASS telescope interior
    2MASS Telescope

    As you can tell, the light-blocking gas and dust has practically disappeared, and that’s no coincidence. Although we don’t normally think about it, the wavelengths of all types of light that interact with something is highly dependent on the size of the object itself. This is why there are large holes on your microwave door: they allow visible light through but block the microwaves that cook and heat your food. (Don’t scrape the holes off, not even in the interest of science!)

    And as we noted earlier, for the dust grains in our galaxy, visible light is easily absorbed while infrared passes through uninhibited. This is specific to the types of molecules and how they’re bound together in the interstellar medium.

    6
    Image credit: retrieved from Tracy DeLiberty of U. of Delaware, via http://www.udel.edu/.

    If we take a look at our atmosphere instead, the converse is true: visible light passes through the molecules and particles present very easily, while infrared is more easily absorbed. That’s why, to really get a handle on what’s out there beyond the plane of our galaxy, we can’t do it from the Earth’s surface; the atmosphere’s infrared light-blocking properties are simply too good.

    To look beyond our galactic plane, and spy the Universe beyond, we simply have to go to space.

    Lucky for you, we have, and the results are mind-blowing.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    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.

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 9:54 am on November 21, 2014 Permalink | Reply
    Tags: , , , Astrophysics, , ,   

    From SPACE.com: “Planet Uranus: Facts About Its Name, Moons and Orbit” 

    space-dot-com logo

    SPACE.com

    November 18, 2014
    Charles Q. Choi

    Uranus is the seventh planet from the sun and the first to be discovered by scientists. Although Uranus is visible to the naked eye, it was long mistaken as a star because of the planet’s dimness and slow orbit. The planet is also notable for its dramatic tilt, which causes its axis to point nearly directly at the sun.

    ur

    British astronomer William Herschel discovered Uranus accidentally on March 13, 1781, with his telescope while surveying all stars down to those about 10 times dimmer than can be seen by the naked eye. One “star” seemed different, and within a year Uranus was shown to follow a planetary orbit.

    Uranuswas named after the Greek sky deity Ouranos, the earliest of the lords of the heavens. It is the only planet to be named after a Greek god rather than a Roman one. Before the name was settled on, many names had been proposed for the new planet, including Hypercronius (“above Saturn”), Minerva (the Roman goddess of wisdom), and Herschel, after its discoverer. To flatter King George III of England, Herschel himself offered Georgium Sidus (“The Georgian Planet”) as a name, but that idea was unpopular outside of England and George’s native Hanover. German astronomer Johann Bode, who detailed Uranus’ orbit, gave the planet its ultimate name.

    Physical characteristics

    Uranusis blue-green in color, the result of methane in its mostly hydrogen-helium atmosphere. The planet is often dubbed an ice giant, since 80 percent or more of its mass is made up of a fluid mix of water, methane, and ammonia ices.

    Unlike the other planets of the solar system, Uranus is tilted so far that it essentially orbits the sun on its side, with the axis of its spin nearly pointing at the star. This unusual orientation might be due to a collision with a planet-size body, or several small bodies, soon after it was formed.

    This unusual tilt gives rise to extreme seasons roughly 20 years long, meaning that for nearly a quarter of the Uranian year, equal to 84 Earth-years, the sun shines directly over each pole, leaving the other half of the planet to experience a long, dark, cold winter.

    The magnetic poles of most planets are typically lined up with the axis along which it rotates, but Uranus’ magnetic field is tilted, with its magnetic axis tipped over nearly 60 degrees from the planet’s axis of rotation. According to Norman F. Ness, et al, in an article in the journal Science, this leads to a strangely lopsided magnetic field for Uranus, with the strength of the field at the northern hemisphere’s surface being up to more than 10 times that of the strength at the southern hemisphere’s surface, affecting the formation of the auroras.

    Orbital characteristics

    Average distance from the sun: 1,783,939,400 miles (2,870,972,200 kilometers). By comparison: 19.191 times that of Earth

    Perihelion (closest approach to the sun): 1,699,800,000 miles (2,735,560,000 km). By comparison: 18.60 times that of Earth

    Aphelion (farthest distance from sun): 1,868,080,000 miles (3,006,390,000 km). By comparison: 19.76 times that of Earth
    The planet Uranus, seventh planet from the sun, is a giant ball of gas and liquid and was the first planet discovered with a telescope.

    ur
    Credit: Karl Tate, SPACE.com

    Composition & structure

    Atmospheric composition (by volume): 82.5 percent hydrogen, 15.2 percent helium, 2.3 percent methane

    Magnetic field: Magnetic pole tilt compared to rotational axis: 58.6 degrees

    Composition: The overall composition of Uranus is, by mass, thought to be about 25 percent rock, 60 to 70 percent ice, and 5 to 15 percent hydrogen and helium.

    Internal structure: Mantle of water, ammonia and methane ices; core of iron and magnesium-silicate
    Orbit & rotation

    Axial tilt: 97.77 degrees, compared to Earth’s 23.5 degrees

    Seasonal cycle & length: Approximately 21 years per season

    Orbital period: Approximately 84 Earth years
    Uranus’ climate

    The extreme axial tilt Uranus experiences can give rise to unusual weather. As sunlight reaches some areas for the first time in years, it heats up the atmosphere, triggering gigantic springtime storms roughly the size of North America, according to NASA.

    Ironically, when Voyager 2 first imaged Uranus in 1986 at the height of summer in its south, it saw a bland-looking sphere with only about 10 or so visible clouds, leading to it to be dubbed “the most boring planet,” writes astronomer Heidi Hammel in The Ice Giant Systems of Uranus and Neptune, a chapter in Solar System Update (Springer, 2007). It took decades later, when advanced telescopes such as Hubble came into play and the seasons changed, to see extreme weather on Uranus, where fast-moving winds can reach speeds of up to 560 miles (900 kilometers) per hour.

    NASA Voyager 2
    NASA/Voyager 2

    NASA Hubble Telescope
    NASA/ESA Hubble

    The rings of Uranus

    The rings of Uranus were the first to be seen after Saturn’s. They were a significant discovery, because it helped astronomers understand that rings are a common feature of planets, not merely a peculiarity of Saturn.

    Uranus possesses two sets of rings. The inner system of rings consists mostly of narrow, dark rings, while an outer system of two more-distant rings, discovered by the Hubble Space Telescope, are brightly colored, one red, one blue. Scientists have now identified 13 known rings around Uranus.
    Uranus’ moons

    Uranus has 27 known moons. Instead of being named after figures from Greek or Roman mythology, its first four moons were named after magical spirits in English literature, such as William Shakespeare’s “A Midsummer Night’s Dream” and Alexander Pope’s “The Rape of the Lock.” Since then, astronomers have continued this tradition, drawing names for the moons from the works of Shakespeare or Pope.

    Oberon and Titania are the largest Uranian moons, and were the first to be discovered, by Herschel in 1787. William Lassell, who was the first to see a moon orbiting Neptune, discovered the next two, Ariel and Umbriel. Then nearly a century passed before Miranda was found in 1948.

    Then, Voyager 2 visited the Uranian system in 1986 and found an additional 10, all just 16 to 96 miles (26-154 km) in diameter — Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Portia, Rosalind, Cressida and Belinda — and each roughly made half of water ice and half of rock. Since then, astronomers using the Hubble Space Telescope and ground-based observatories have raised the total to 27 known moons, and spotting these was tricky — they are as little as 8 to 10 miles (12 to 16 km) across, blacker than asphalt, and nearly 3 billion miles (4.8 billion km) away.

    Between Cordelia, Ophelia and Miranda is a swarm of eight small satellites crowded together so tightly that astronomers don’t yet understand how the little moons have managed to avoid crashing into each other. Scientists suspect there might still be more moons, closer to Uranus than any known.

    In addition to moons, Uranus may also have a collection of Trojan asteroids — objects that share the same orbit as the planet — in a special region known as a Lagrangian point. The first was discovered in 2013, despite claims that the planet’s Langrangian point would be too unstable to host such bodies.

    Research & exploration

    NASA’s Voyager 2 was the first and as yet only spacecraft to visit Uranus. It discovered 10 previously unknown moons, and investigated its unusually tilted magnetic field.

    In 2013, the Planetary Science Decadal Survey recommended NASA consider a mission to the icy planet.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 9:31 am on November 21, 2014 Permalink | Reply
    Tags: , Astrophysics, , , , ,   

    From Science Daily: “How to estimate the magnetic field of an exoplanet” 

    ScienceDaily Icon

    [Similar material to an earlier post; but a different slant.]

    Science Daily

    November 20, 2014
    Source: Lomonosov Moscow State University

    Scientists developed a new method which allows to estimate the magnetic field of a distant exoplanet, i.e., a planet, which is located outside the Solar system and orbits a different star. Moreover, they managed to estimate the value of the magnetic moment of the planet HD 209458b.The group of scientists including one of the researchers of the Lomonosov Moscow State University (Russia) published their article in the Science magazine.

    2
    Size comparison of HD 209458 b with Jupiter.

    hj
    Artist’s interpretation of Planet HD 209458b. Scientists have now estimated the value of the magnetic moment of the planet HD 209458b.
    Credit: NASA/ESA/CNRS/Alfred Vidal-Madjar

    In the two decades which passed since the discovery of the first planet outside the Solar system, astronomers have made a great progress in the study of these objects. While 20 years ago a big event was even the discovery of a new planet, nowadays astronomers are able to consider their moons, atmosphere and climate and other characteristics similar to the ones of the planets in the Solar system. One of the important properties of both solid and gaseous planets is their possible magnetic field and its magnitude. On Earth it protects all the living creatures from the dangerous cosmic rays and helps animals to navigate in space.

    Kristina Kislyakova of the Space Research Institute of the Austrian Academy of Sciences in Graz together with an international group of physicists for the first time ever was able to estimate the value of the magnetic moment and the shape of the magnetosphere of the exoplanet HD 209458b. Maxim Khodachenko, a researcher at the Department of Radiation and computational methods of the Skobeltsyn Institute of Nuclear Physics of the Lomonosov Moscow State University, is also one of the authors of the article. He also works at the Space Research Institute of the Austrian Academy of Sciences.

    Planet HD 209458b (Osiris) is a hot Jupiter, approximately one third larger and lighter than Jupiter. It is a hot gaseous giant orbiting very close to the host star HD 209458. HD 209458b accomplishes one revolution around the host star for only 3.5 Earth days. It has been known to astronomers for a long time and is relatively well studied. In particular, it is the first planet where the atmosphere was detected. Therefore, for many scientists it has become a model object for the development of their hypotheses.

    Scientists used the observations of the Hubble Space Telescope of the HD 209458b in the hydrogen Lyman-alpha line at the time of transit, when the planet crosses the stellar disc as seen from Earth. At first, the scientists studied the absorption of the star radiation by the atmosphere of the planet. Afterwards they were able to estimate the shape of the gas cloud surrounding the hot Jupiter, and, based on these results, the size and the configuration of the magnetosphere.

    NASA Hubble Telescope
    NASA/ESA Hubble

    “We modeled the formation of the cloud of hot hydrogen around the planet and showed that only one configuration, which corresponds to specific values of the magnetic moment and the parameters of the stellar wind, allowed us to reproduce the observations,” explained Kristina Kislyakova.

    To make the model more accurate, scientists accounted for many factors that define the interaction between the stellar wind and the atmosphere of the planet: so-called charge exchange between the stellar wind and the neutral atmospheric particles and their ionization, gravitational effects, pressure, radiation acceleration, and the spectral line broadening.

    At present, scientists believe that the size of the atomic hydrogen envelope is defined by the interaction between the gas outflows from the planet and the incoming stellar wind protons. Similarly to Earth, the interaction of the atmosphere with the stellar wind occurs above the magnetosphere. By knowing the parameters of an atomic hydrogen cloud, one can estimate the size of the magnetosphere by means of a specific model.

    Since direct measurements of the magnetic field of exoplanets are currently impossible, the indirect methods are broadly used, for example, using the radio observations. There exist a number of attempts to detect the radio emission from the planet HD 209458b. However, because of the large distances the attempts to detect the radio emission from exoplanets have yet been unsuccessful.

    “The planet’s magnetosphere was relatively small being only 2.9 planetary radii corresponding to a magnetic moment of only 10% of the magnetic moment of Jupiter,” explained Kislyakova, a graduate of the Lobachevsky State University of Nizhny Novgorod. According to her, it is consistent with the estimates of the effectiveness of the planetary dynamo for this planet.

    “This method can be used for every planet, including Earth-like planets, if there exist an extended high energetic hydrogen envelope around them,” summarized Maxim Khodachenko.

    Journal Reference:

    K. G. Kislyakova, M. Holmstrom, H. Lammer, P. Odert, M. L. Khodachenko. Magnetic moment and plasma environment of HD 209458b as determined from Ly observations. Science, 2014; 346 (6212): 981 DOI: 10.1126/science.1257829

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    ScienceDaily is one of the Internet’s most popular science news web sites. Since starting in 1995, the award-winning site has earned the loyalty of students, researchers, healthcare professionals, government agencies, educators and the general public around the world. Now with more than 3 million monthly visitors, ScienceDaily generates nearly 15 million page views a month and is steadily growing in its global audience.

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 355 other followers

%d bloggers like this: