Baby it’s cold outside

By Phil Plait | April 10, 2008 10:23 am

Astronomers have found the coldest (well, least hot) brown dwarf in deep space: by the name of CFBDS J005910.83-011401.3, it has a temperature of 350 Celsius (660 Fahrenheit). That’s still hotter than you need to bake cookies, but compared to a star it’s practically frigid.

Now we should be careful with our semantics here. Planets have been detected around other stars which may be lower in temperature than this object, I suspect, but their temperatures have not been directly determined. In the case of CFBDSetc., the temperature was found by looking at its spectrum. The presence of ammonia in the atmosphere of this object was a dead giveaway that it’s cold; ammonia breaks apart when it gets too hot. Other features allow a temperature to be found, and 350 C is pretty cool. Other brown dwarfs are hotter, more like in the 1000 C range or so. The warmer an object, the brighter it glows, and the easier it is to find. So warmer ones are found first, and cooler ones are tougher.

Brown dwarfs are weird. They’re objects with masses between that of a planet and a star, and the first were found just a few years ago. They are more massive than planets — CFSBD is 15 – 30 times the mass of Jupiter — but still far less massive than a star, and cannot continuously fuse hydrogen to helium in their cores. The ones we find tend to be young and still hot from their formation. Eventually they cool off, since they cannot generate heat in their cores as stars do. Obviously, CFSBD has been around the block a few times to have had enough time to cool down so much. That alone makes it interesting.

But since it’s so cool, its atmosphere is more like a planet than a star. Getting direct observations of a planet around another star is incredibly difficult, so studying this weird object will no doubt generate insight into planetary atmospheres with temperatures intermediate between what we see here in our solar system and brown dwarfs we detect out in space.

And now that we’ve found one, I’ll just bet more will pop up in the next few years. Once we have enough to get statistics on them, our knowledge will increase rapidly, just as it did when brown dwarfs were discovered in the first place.

Funny– as I write this, it’s snowing outside. Cold is relative, I suppose, but one thing I like about new discoveries is how they stretch our minds just a little bit, and make us re-evaluate what we mean by things like "hot" and "cold". I’ll still put on a coat and gloves when I go outside in a few minutes, but in my mind I’ll wonder what it’s like to walk across Mars, where it’s so much colder, or Mercury, where it’s a tad bit warmer. And what would it look like to hover over a brown dwarf, orbiting an object that’s the physical size of Jupiter, but is neither a planet nor a star? What odd weather patterns would paint the view?

The Universe is weird. I’m glad we get the chance to take a look around.

CATEGORIZED UNDER: Astronomy, Cool stuff, Science

Comments (22)

  1. Dan

    Hmm… You can’t even cook a decent steak on that thing.

  2. ccpetersen

    Funny… I was just working on a press release for Gemini about this…

    ;)

  3. Gnat

    Okay, I have a question: what will it be like when it completely cools? A dense rock? That doesn’t seem correct…but when you said “its atmosphere is more like a planet than a star”, all I can imagine is a rock.

    Another question: how long will it take to completely cool?

  4. Heck, Venus is hotter on its surface (800 F) than this turkey.

  5. Dan

    Wow. Do we sound like a bunch of haters or what? Oh yeah. It’s always fun picking on the weak ones, isn’t it? Huh?

    hahaha…

  6. Kesstra

    I am curious. Can and will this thing completely cool? I mean what if the universe if filled with these dead dark star/planetoid things with no heat signature or affecting anything gravitionally doesn’t that make it almost impossible to find? So there could be millions out there. Am I worng?

  7. Thad Hatchett

    “And now that we’ve found one, I’ll just bet more will pop up in the next few years.” – BA

    I’d say these will be really tough to find. Being so cool, if they are in orbit around another star they’d be nearly impossible to see. This one was isolated and floating free making it a little “easier”.

  8. Rowsdower

    “I’ll still put on a coat and gloves when I go outside in a few minutes, but in my mind I’ll wonder what it’s like to walk across Mars, where it’s so much colder, or Mercury, where it’s a tad bit warmer.”

    What, without pants?

  9. Bear with me here-

    Once the temperature gets below 100C, and liquid water is able to form…. how long would it last in that range of 0-100C? Then, how bad is the actual radiation? What would the gravity be like on the surface of a brown dwarf?

    What I’m getting at is…. could these support life? By that, I don’t mean you and I – I mean independently evolved organisms of whatever sort that would be able to survive this environment.

    Seems there’s energy to be used – add in some organic soup of some sort, and off you go – just have a couple of comets and ice chunks slamming in, and soup is served.

    OF COURSE, I am not a physicist / astronomer / anything remotely related, so it’s entirely possible that this entire comment is nonesense, but it was a nice though experiment on my end. :)

  10. Chip

    BA: “…what would it look like to hover over a brown dwarf, orbiting an object that’s the physical size of Jupiter, but is neither a planet nor a star? What odd weather patterns would paint the view?”

    If we imagine an Earth-like planet orbiting it at just the right distance to allow us to go outside without winter coats and gloves* – daytime light from a Brown Dwarf would probably not result in a blue sky. Our planet might also find itself in tidal lock around this tiny star which could make for weird weather patterns. Yes – its fun to imagine – stretches to mind!

    * I realize its probably unlikely that planets just like Earth could form around brown dwarfs but let’s pretend it got moved there. ;)

  11. Quiet_Desperation

    BA: Brown dwarfs are weird.

    Can anything that exists be weird? It is what it is.

    Dan: Wow. Do we sound like a bunch of haters or what? Oh yeah. It’s always fun picking on the weak ones, isn’t it? Huh?

    (blank stare)

    What?!

    You from the Brown Dwarf Defense League or something?

  12. Torbjörn Larsson, OM

    You can’t even cook a decent steak on that thing.

    Que? The core temperature of a medium steak is 60 Celsius – this girl is 350 Celsius hot. Grilling can be a tad less (from say 340 Celsius). With the pressures involved I don’t think conduction will be a problem.

    Btw, to do a decent steak at low temperatures you can do a “tjälknut”, roast a steak 10-12 h @ 100 Celsius in oven until done.

  13. TheSkier

    I am only an undergraduate in astrophysics, and what I’m saying is from my intuition – not calculations.

    @jeremy – remember 0-100 C is at Earth pressure, so it won’t be the same on the star. The surface gravity is probably 5 times that on Earth.
    The more massive a body, the longer it takes to cool down, and especially at lower temperatures because it’s not radiating as much energy (per time), so it could be in the range of liquid water for millions of years. I personally doubt the existence of life on a brown dwarf: I don’t see various, more complicated, molecules being able to form

    @gnat – It won’t be a dense rock. Stars (and I assume brown dwarfs) are comprised almost entirely of Hydrogen, and the fact that this is fairly old would suggest lower metallicity. Since it cannot sustain fusion, it won’t form the heavier elements to form rock (Carbon or silicon for instance) – at best it will form some Helium.

    Our Sun has an atmosphere above the photosphere (where the plasma is no longer opaque).

    As for completely cooling, it would asymptotically approach whatever the CMB radiation temperature is at the time.

    @Chip – If I recall correctly, the first definitive exoplanet was found around a Pulsar! How bizarre: that would certainly seem unlikely. I see no reason why an Earth body would be any less likely around this star than the Sun.

  14. The Skier –

    way to completely ruin my fun. jerk. why’d you have to go and bring reality into a complete fantasy?

    sheesh.

    (yes, I kid)

  15. Kullat Nunu

    This object may be too cool (pun intended) to be classified as a T type star/brown dwarf. It seems to be about time to expand the old OBAFGKMLT list with the letter Y.

  16. Shache

    i was wondering, how could this be the coldest brown dwarf if we haven’t even discovered how big space is. There could be even colder stars that we haven’t even discovered yet. Unless you mean the coldest brown dwarf yet discovered, there is probably a colder star. Now that’s something to think about.

  17. complex_field

    This dwarf’s temperature was measured directly? Was Wien’s employed for this? If so, how is the law used in real-life?

  18. Is there a definition between planet and brown dwarf yet? Last I knew it was still kinda fuzzy.

  19. Tyler Durden

    Fascinating. A simple dutch oven can create more heat than this star! (Did a little googling and found they can get up to as hot as 1000F.)

  20. Tod

    Phil wrote: “The Universe is weird. I’m glad we get the chance to take a look around.”

    That’s one awesome and very true statement that encapsulates what life means to me: Sniff the flowers, greet a stranger, protect a child, and just generally observe what’s around you.

    Thanks, Phil, and thanks for the always great posts.

  21. Steven Charles Raine

    Yep, that is,indeed, a pretty cool discovery! ;-)

    CFSD..etc ..numerals … is a horrible name though – lets give a proper one like, say, New Chile! ;-)

    Incidentally, I don’t think of Brown dwarfs as being “failed stars” so much as “really, really, successful Jupiters!”

    Given ‘NewChile” is cooler than the surface of Venus & the (currently)sunny side of Mercury, I’m curious over whether lead would melt there – would it?

    (It would on Venus / sunnyside Mercury hence my qu.)

  22. John Phillips, FCD

    @Steven Charles Raine:

    “Incidentally, I don’t think of Brown dwarfs as being “failed stars” so much as “really, really, successful Jupiters!””

    :) :) :)

    Lead melts at 327C

NEW ON DISCOVER
OPEN
CITIZEN SCIENCE
ADVERTISEMENT

Discover's Newsletter

Sign up to get the latest science news delivered weekly right to your inbox!

ADVERTISEMENT

See More

ADVERTISEMENT
Collapse bottom bar
+

Login to your Account

X
E-mail address:
Password:
Remember me
Forgot your password?
No problem. Click here to have it e-mailed to you.

Not Registered Yet?

Register now for FREE. Registration only takes a few minutes to complete. Register now »