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Cool brown dwarf may be a newfound neighbor of the sun

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Closest, coolest brown dwarfBrown dwarfs straddle the divide between planets and stars—they are celestial objects too small to burn hydrogen in fusion reactions, as stars do, but they are large enough to sustain other kinds of fusion. At least a few even harbor orbiting planets. The International Astronomical Union sets the planet–brown dwarf boundary at 13 times the mass of Jupiter. But that mass limit is an imperfect definition—what of brown dwarf–size bodies that orbit stars, behaving themselves like supersized planets?

Firming up the line between planets and brown dwarfs will become more pressing as the coolest, dimmest brown dwarfs soon reveal themselves to the new generation of astronomical instruments. NASA’s WISE satellite, for instance, is highly adept at spotting cool, dim objects. Since its launch in December 2009, WISE has already discovered seven comets and 30 near-Earth asteroids, and its operators expect that WISE will spot many brown dwarfs as well during its sky-surveying mission.

In the meantime, an international team led by Philip Lucas of the University of Hertfordshire in England claims discovery of what could be the nearest and coolest brown dwarf yet. Lucas and his colleagues reported their finding in a paper posted to the preprint repository on April 2. They used data from a survey of the sky taken at the U.K. Infrared Telescope in Hawaii to uncover UGPS 0722-05, a brown dwarf with a temperature of only about 125 to 225 degrees Celsius. The coolest previously known brown dwarfs are in the range of 225 to 275 degrees C.

Based on preliminary distance measurements, the object appears to be floating free in interstellar space some 9.5 light-years away, closer than the binary brown dwarfs of the Epsilon Indi system 11.8 light-years distant. If it were a normal star it would rank among the dozen nearest stellar companions to the sun. (The closest star, Proxima Centauri, is 4.2 light-years from the sun.)

Astrophysicist Adam Burgasser of the University of California, San Diego, was not a member of Lucas’s team but has already been involved in follow-up observations of the object. "I think it’s a very interesting find," Burgasser says, "although I would caution it is still unclear how close the source is, as there are only a few astrometric measurements made thus far." He notes also that temperatures can be difficult to pin down for the coolest varieties of brown dwarfs, and that the research has not yet been peer-reviewed. "In any case, the group’s discovery has gotten several of us very excited," Burgasser says, "and we do hope it pans out to be as close as they claim."

Artist’s impression of a cool brown dwarf: NASA/JPL-Caltech/R. Hurt (SSC/Caltech)


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  1. 1. nfiertel 4:42 pm 04/9/2010

    How can a brown dwarf sustain any kind of fusion? Considering if a brown dwarf is a gaseous body, there would be convection and thus the surface temperature of such a dwarf if it were to have some form of atomic energy production of gaseous elements there surely would have a much higher surface temperature. Theoretically if such a body had heavy elements there could be as found on the earth thorium and uranium for example whose natural fission into other elements maintain core temperatures but if as I presume a brown dwarf is core-less and fully a gaseous or gas/metallic hydrogen body with little or no heavy elements in a central core, I can not conceive of anything more than fission heating from diluted unstable atomic elements. I thus dispute the reference offhand of other fusion activities without some clarification

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  2. 2. Wayne Williamson 5:55 pm 04/9/2010

    I wish the authors would post the temps in kelvin…what does celsius have to do with space…other than then that keep finding them….i think there will be more found closer by…failed systems…

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  3. 3. DEP 2:05 am 04/10/2010


    I’m DEP. These Massive Dark Objects make up the Dark Matter in our universe. I plan to introduce this theory in a forthcoming book; hopefully.

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  4. 4. bertwindon 7:56 am 04/10/2010

    Yes, maybe the answer lies in gaseous and atomic elements. Whose theory is it ?

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  5. 5. bertwindon 7:59 am 04/10/2010

    Well if you add 2 hundred and seventy three to a "Celcius " temperature, you will then have a "Kelvin" temperature 0 and happiness, I trust !

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  6. 6. bertwindon 8:08 am 04/10/2010

    It made us and now we own it !

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  7. 7. Wayne Williamson 3:12 pm 04/11/2010

    bertwindon…just doing some relative comparisons with our own "brown dwarfs" jupiter and saturn…celsius really only applies to earth….a water planet….

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  8. 8. Vermillion 7:59 pm 04/11/2010

    I don’t understand the title of this article. Why is it "Cool Brown Dwarf MAY Be a Newfound Neighbor of the Sun"? It IS a newfound neighbor of the Sun. As discussed on the New Scientist site, this object’s distance has been measured via parallax, which is the gold standard for distance determination. There is some uncertainty in the parallax, but there’s no question this object is very close to the Sun.

    Incidentally, contrary to what’s said in the first paragraph, there are stars that shine without using nuclear reactions. For example, T Tauri stars use gravitational contraction to shine.

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  9. 9. Robert Mackay 7:24 am 04/12/2010

    Planet X

    By Robert Mackay
    I am not a doom and gloomer, but I do have an inquiring mind. I’ve been following the
    fascinating theories on T.V., Radio, the Internet, and in Print about the possibility of a "Planet
    X" appearing. It supposedly causes catastrophic shifts in our Continental Landmasses. There
    is ample evidence to show periodic slippage of the Earth’s Crust. Many Excavations show that
    800 or so million years ago, Alaska and the North Pole were on the Equator. Tropical Animal
    and Plant fossils have been found at the South Pole. This may or may not be related, but
    there have been many reversals in the Polarity of the Earth’s Magnetic Poles.

    My research has taken me to the works of Famous Astro-Physicists, Well-Known Geologists,
    University Studies, and many kooks.

    Here is what Does make sense to me: A Good Number of Experts theorize that there could be
    a "Planet X", or a dim Brown-Dwarf Star, that has a long elliptical orbit that brings it close to
    the Sun every 3600 years or so. The OPPOSING GRAVITY from both huge bodies destabilizes
    the Earth’s Crust, and bad things happen.

    I generally agree, except that I see a few things that need to be tweaked. But first, here is
    some background:

    Space is full of microscopic dust, and since each molecule of dust is matter, then each
    molecule has gravity that attracts other molecules. Over millions of years, large amounts
    of dust gather to form Planets. As Planets keep attracting more and more dust and objects,
    they keep growing. As Gravity increases, it squashes the the center of a Planet into liquid.
    The outside of a Planet cools and becomes solid-bonded-matter, an unstable Crust that sits
    on spinning molten liquid lava.

    Planets continue to attract more matter, and over millions more years grow into Gas Giants
    like Jupiter. The gravity has gotten so strong that the liquid center, and the solid crust are
    squeezed into becoming extremely dense Gas.

    After more millions of years, a Planet grows to the point that the massive Gravity causes
    an Explosion that lasts for more millions of years. The Planet has become a Star.

    "Planet X" cannot be a Planet, and here is why: There are 2 independent calculations of
    the maximum distance that Planet X reaches in its orbit from the Sun, 235 parsecs, and
    469 parsecs. (A parsec is the average distance the Earth has from the Sun, 93 million miles).
    Let’s take the shortest and do some math. Gravity and nearly all energy follow the "Inverse
    Square Law". If you are at a concert, and the music is too loud, and you move halfway
    closer to the speaker, the volume does not just double, it is 2 X 2, or 4 times louder.
    Move one half of the remaining distance closer, and the volume is 4 X 4 or 16 times the
    original volume. The same principle works in reverse.

    If Planet X moves 235 parsecs from the Sun, the gravitational pull from the Sun would
    be 1/235 X 1/235 = less than one 55 thousandths of the gravity felt by Earth from the Sun. For
    Planet X to have the mass large enough to create the catastrophic disruptions is does
    in our Solar System, this small amount of gravity could not possibly hold it in orbit.
    Something else such as gravity from the center of the Galaxy would have captured it.

    A Brown Dwarf CANNOT be a Gas Planet in the process of becoming a Star. EXPLOSIONS DO
    NOT START SLOWLY. A Brown Dwarf is an Old Star that has gone through most of its Life
    Cycle. It has been a Massive Giant, had a first Nova, regrouped, and then had a Super Nova,
    shrunk to a White Dwarf, and is in the process of condensing and becoming a Black Hole.
    The Brown Dwarf has the Mass of a Large Star that has been crushed into the size of a Large
    Planet. The Gravity is so intense that very little heat or light can escape, and this is why a
    Dwarf is extremely difficult for Astronomers to find.

    So here’s what the Experts are missing: A Brown Dwarf Star would have dozens of times
    more mass than our Sun, and therefore could not revolve around our sun. It is The Sun,
    together with all of us, and our Neighbor Planets, that revolve around the Brown Dwarf. Our
    orbit takes over 3600 years, and we move extremely fast through our very tight Elliptical
    Path. I do not buy the theory that all Brown Dwarfs are "failed stars".

    Are we looking at a train wreck around the corner? Possibly, but if we are, we might have
    learned enough to minimize the damage. It is likely that the Brown Dwarf holds Planets,
    and maybe some have Intelligent Life that is smarter than us.

    N.A.S.A., and some Scientists are puzzled about many of our Satellites being pulled slightly
    away from where they should be. There is a great mystery about why so few Sunspots
    occurred in 2008. If we are approaching a Brown Dwarf that surely has vastly more gravity
    than our Sun, it would also have vastly more Electro-Magnetic Energy that could be disrupting
    the Normal Sun-Spot Cycle………Millions of years ago something blew up a Planet that
    orbited between Mars and Jupiter. Today we call it the Asteroid belt.
    Page two, Planet X

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  10. 10. smittyg21 9:05 am 04/30/2010

    Robert Mackay
    Please in the future check your facts. I respect your theory about the nature of Brown Dwarfs but would like to see a more convincing argument (observations). Also, a parsec is roughly 3.5 light years I believe that you are referring to an astronomical unit.

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  11. 11. scotthenderson37 3:13 pm 05/6/2010

    your math is wrong as a parsec refers to 3.2 light years not 93 million miles. and u also mistake magnetic tides for gravity. gravity increases between objects as they get more distance from each other hence why the earth doesnt fly out of orbit at its orbital apex.

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  12. 12. Vermillion 8:39 am 06/25/2010

    This just in: New Scientist is reporting a new parallax for this object. It’s several light-years farther than had been thought, but it’s still a neighbor of the Sun. See .

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