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Frigid Brown Dwarf Found Only 7.2 Light-Years Away

Posted by Soulskill on from the interstellar-stalker-hiding-in-the-bushes dept.

An anonymous reader writes "Astronomer Kevin Luhman just found the 7th closest star to the sun. It's a mere 7.2 light-years away, discovered using NASA's Spitzer and WISE telescopes. How could it exist so close for so long without us knowing? It's a brown dwarf — barely a star at all. 'Brown dwarfs are star-like objects that are more massive than planets, but not quite massive enough to ignite sustained fusion in their cores. Hydrogen fusion is what powers the Sun, and makes it hot; it's the mighty pressure of the Sun's core that makes that happen. Brown dwarfs don't have the oomph needed to keep that going.' This small almost-star is downright chilly at around 225-260 Kelvin. That's -48 to -13 C (or -54 to 9 F). As Phil Plait points out, that's not much different from the temperature in the freezer in your kitchen. He adds, 'It implies this object is very old, too, because it would've been a few thousands degrees when it formed, and would take at least a billion years to cool down to its current chilly temperature. It's hard to determine how old it actually is, but it's most likely 1-10 billion years old. It has a very low mass, too, probably between 3 and 10 times the mass of Jupiter. That's pretty lightweight even for a brown dwarf. And here's another amazing thing about it: It might be a planet. What I mean is, it may have formed around a star like a planet does, then got ejected by gravitational interactions with other planets.'"

6 of 142 comments (clear)

  1. Okay, stupid question from a non-astronomer... by Anonymous Coward · · Score: 2, Interesting

    I keep hearing about "Dark Matter" as an explanation for how galaxies don't fly apart due to the force generated by their rotation, but I can't help thinking that all that mass we're looking for in galaxies could be stuff like this. Regular matter that just doesn't generate enough heat or light for us to have noticed prior to this.

    Could the question of how galaxies rotate be answered by large quantities of objects such as these?

    1. Re:Okay, stupid question from a non-astronomer... by TrollstonButterbeans · · Score: 1, Interesting

      Dark matter and dark energy are kludges thrown into an equation because the equation is incomplete.

      Like a formula with 2 unknowns, X and Y, with undefined values for each.

      Dark matter might as well be called "behavior of gravity or a gravity-like force that we don't understand or observations that could be wrong or misunderstood so far".

      Dark energy might as well be called "Looks like we might have expansion if we understand the observations right and since we don't understand this either, let us say there is dark energy".

      Do you think 96% of the universe is dark matter and dark energy or do you think that more likely our understanding is 96% incomplete or that some ideas of measurements at great distances are terribly wrong due to something we are assuming (and shouldn't be) or something we didn't think of so far or that our ideas of the fundamental forces still have some major discoveries?

      We have some great and compelling ideas in cosmology and physics, but we are not so far along that we don't have much more to go, hell we've supposedly observed quark quartets -- which I guess aren't supposed to happen --- so let's assume the safe thing = we have a lot to learn about the universe still.

      --
      Priest: "Universe from nothing, no laws of physics, sped up time"+ huge discrepancies. Creationism? No. Big Bang Theory
  2. Stupid question from a non-astronomer by IDtheTarget · · Score: 3, Interesting

    Sorry for the double-post, didn't realize I wasn't logged in when I posted this previously

    I keep hearing about "Dark Matter" as an explanation for how galaxies don't fly apart due to the force generated by their rotation, but I can't help thinking that all that mass we're looking for in galaxies could be stuff like this. Regular matter that just doesn't generate enough heat or light for us to have noticed prior to this.

    Could the question of how galaxies rotate be answered by large quantities of objects such as these?

    1. Re:Stupid question from a non-astronomer by aardvarkjoe · · Score: 5, Interesting

      The Wikipedia article on dark matter discusses this in depth. Although I'm no astrophysicist and can't vouch for the article's accuracy, it does outline some of the reasons why those studying it believe that objects like this cannot account for the amount of dark matter required to explain how galaxies behave.

      --

      How can we continue to believe in a just universe and freedom to eat crackers if we have no ale?
    2. Re:Stupid question from a non-astronomer by idji · · Score: 5, Interesting

      Your question is whether Dark Matter could be real and observed MACHOs.
      The other main option is that Dark Matter could be hypothetical WIMPs
      Numerous experiments have ruled out MACHOS as making up the bulk of Dark Matter. The missing mass problem is not solved by MACHOs.
      At the moment the WIMPS are beating the MACHOS.
      See also History of the search for Dark Matter

  3. Perhaps a Dyson Sphere? by Lew+Pitcher · · Score: 5, Interesting

    Two elements of TFA caught my eye:

    1. The object radiates at "around 225 – 260 Kelvins", or (if I got the math correct) 12.878971111111
      micrometers
    2. the object "has a very low mass, too, probably between 3 and 10 times the mass of Jupiter".

    Together, these figures are within the range for a type I (or, maybe even a type II) Dyson sphere.
    And, it is only 7.2 light years away?

    Yes, it is very probably the Brown Dwarf that the astronomers think it is.
    But, imagine. It could be a Dyson sphere; our first evidence of advanced life beyond the earth.

    --

    "values of beta will give rise to dom!"