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Storm-like Activity Found on Brown Dwarfs 23

Posted by michael from the since-my-gal-and-I-ain't-together dept.
Schwamm writes "Yesterday, scientists at NASA and UCLA announced that they had spotted storm-like activity on brown dwarfs, balls of gas larger than Jupiter and Saturn, but too small to burn hydrogen. These storms on the brown dwarfs make the Great Red Spot on Jupiter look like a 'small squall'. Here's another article at CNN."
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Storm-like Activity Found on Brown Dwarfs More

Storm-like Activity Found on Brown Dwarfs

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  • So does this mean that Brown Dwarfs are more closely related to planets than to stars?
    I've always though of them as smallish, lukewarm stars myself, but I'm not a professional astronomer or anything.
    Does anyone out there have more info on this?
    What's the most widely accepted theory nowadays? Is it about to change?
    • From what the article said, make anything big enough, it becomes a star. If it ain't quite big enough, it's a brown dwarf. If it ain't even that big, it's a gas giant planet. The diff is only in how much gas comes together. Apparently, you could just as easily call it a mega-size, mega-hot planet, or call Jupiter a nano-dwarf star.
      • The difference is exactly that: how we think they formed. Stars form in a gas cloud collapse, whereas giant planets form by first accreting a core from an accretion disk around a forming star. To the best of our current understanding, anyway.

        As it turns out, the same people who research brown dwarf atmospheres are also the ones who have a lot to say about exoplanet atmospheres. Moral: in terms of what we can observe, brown dwarfs are basically the same a giant planets.
        • "great big whirls have little whirls
          that feed on their velocity
          and little whirls have lesser whirls
          and so on to viscosity"

          Once we get enough observations done, I'm sure we'll figure out a sequnce, like with stars themselves, in which substellar objects evolve - main sequence: in an accretion disk. Secondary sequence: solo but not quite enough to become a star? Other sequence: gawd-awful big accretion disk that allows the protoplanet to suck up enough matter to start glowing...
          All different kinda scenarios are possible, and given time, they'll observe gobs of them...it's just a matter of years of detections accreting enough data to build actuarial tables.
    • This is a first-class example of how named classes go only so far in describing reality. Apparently spherical gaseous objects in space occur in a variety of sizes. They can't be smaller than a certain size because the gas wouldn't have enough gravity to hold itself together.

      Depending on how big it is, it may be cold, warmish, warm, hot or BINGO! it might have enough mass to start fusing.

      This would be the boundary between "planet" and "star," but the slightly smaller than stellar ones still wouldn't be something you could imagine settling on.

      I'd like to know more about the ones that are just above the brown dwarf level. Could something have terrestrial/Jovian style weather (wind, clouds, hurricanes) and also be fusing inside? That would be cool (hot).
      • Pay no attention to what I said and listen to Cheshire Cat, who sounds like he knows
      • I'd like to know more about the ones that are just above the brown dwarf level. Could something have terrestrial/Jovian style weather (wind, clouds, hurricanes) and also be fusing inside? That would be cool (hot).

        Anything with a convective layer and a heat gradient should have weather, so yes, everything from moons-with-atmospheres on up through full-blown stars should have it.

        The convective layer in red dwarfs is much deeper than in more energetic stars like the sun, as they're cooler (convective layer stops when the star material gets hot enough for radiative transmission to be the dominant heat transfer mechanism). Both still have them, though.

        Winds and storms should be present aplenty, but clouds are a bit iffy. They should only happen where a phase transition is possible (e.g. from plasma to monatomic gas, and from monatomic gas to molecular gases). This would be right at or near the "surface" of a star (maybe deeper for a red dwarf).

        Weather patterns would be very different from conventional weather in layers hot enough to be plasma, as plasma interacts strongly with the star's magnetic field. This region would be anything below a certain depth (i.e. most of the convective layers) and in the corona, for an active star.

        Stars are neat :).
        • "Stars are neat :)."

          Yes. Yes, they are.

          Especially compared to the alternative, which would be the rather unpleasant absence of stars.
    • Can't stars have storms?
    • depends on what you consider a star and what you consider a planet.


  • This quote from the article:

    "The astrophysicists needed some help understanding rain because it's not an important process in most stars."
    ("Most" stars...?!)

    I'm glad I'm not the only one mystified by our planet's weather. (Like, how come it only rains on the days I don't bring an umbrella?)

    The article is really cool, though, especially on the techniques they used as a starting point.

  • I understand intellectually what happens in stars but I find it easier to comprehend whats going on with brown dwarfs. Even though we're talking about heat enough for iron clouds and rain it's a system that's familiar. Interesting.

  • Who is having a hard time visualizing iron rain?
  • The BBC are running an article [bbc.co.uk] on a theory that microbes may play a significant part in terresterial weather patterns. If this theory pans out, it could offer a potentially interesting lead to the search for ET (or mET or uET, if you prefer =). If the Great Red Spot is being maintained by microbes, does that mean it actually qualifies as Space Acne?

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