"Brown dwarfs in general, and Y dwarfs specifically, are a wonderful bridge between stellar and planetary astrophysics, because we think brown dwarfs form like stars, but in many respects look more like gas giant planets like Jupiter," Cushing told SPACE.com. "So when we study Y dwarfs, we are not only learning about stars, but also about the conditions of gas giant exoplanets.
"Brown dwarfs are also much easier to observe because in general, they aren't lost in the glare of an exceedingly bright parent star like the majority of exoplanets are."
"Our ultimate goal is to determine what is the least massive brown dwarf that nature can form and how many of these cold brown dwarfs exist near the sun," Cushing added. "This information will help us understand how low-mass stars and brown dwarfs form in general. So we will be continuing to search the sky using WISE for even colder Y dwarfs. We also want to start studying the known Y dwarfs in more detail to determine more-precise temperature estimates, estimate their masses, determine if any of them are actually binary systems and so on.
"The largest obstacle in studying Y dwarfs is that they are extremely faint, so we require the absolute largest telescopes on Earth and the Hubble Space Telescope and in some cases these telescopes are probably still not sensitive enough."
The scientists detailed their findings about the Y dwarfs in a paper appearing in the Astrophysical Journal and about the 100 new brown dwarfs in a study appearing in the Astrophysical Journal Supplement Series.
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13 Comments
Add CommentSo if it does not support fusion, what is it exactly? Essentially a giant ball of gas?
Reply | Report Abuse | Link to thisMakes you wonder with temperatures that low, if it may be capable of supporting life. That's certainly a rainge in which liquid water can exist, even if perhaps only in cloud form.
Reply | Report Abuse | Link to thisYes they are, although those > 13 * Jupiter's mass (MJ)
Reply | Report Abuse | Link to this"do fuse deuterium and those above ~65 MJ also fuse lithium." Please refer to:
http://en.wikipedia.org/wiki/Brown_dwarf
The wikipedia entry also states:
"A remarkable property of brown dwarfs is that they are all roughly the same radius as Jupiter. At the high end of their mass range (60–90 Jupiter masses), the volume of a brown dwarf is governed primarily by electron degeneracy pressure,[2] as it is in white dwarfs; at the low end of the range (10 Jupiter masses), their volume is governed primarily by Coulomb pressure, as it is in planets. The net result is that the radii of brown dwarfs vary by only 10–15% over the range of possible masses. This can make distinguishing them from planets difficult."
Since they are all about the same diameter as Jupiter and can range up to ~90 Jupiter masses, it seems their principal distinction is the density of their disperse gases and, as discussed in this article, their temperature.
range, I mean...ugh I need to wake up!
Reply | Report Abuse | Link to thisInteresting point, although I think they'd lack the required concentration of complex chemistry necessary to create and sustain life, even if it was delivered by many asteroids...
Reply | Report Abuse | Link to thisIs it really correct to continue calling them dwarfs, likening them to stars at all, when they do not support fusion. We demoted Pluto to a planetoid for less.
Reply | Report Abuse | Link to thisAs I understand, all but the smallest are thought to form just like stars - most are thought to initiate fusion but are unable to sustain it.
Reply | Report Abuse | Link to thisOn the other hand, I have no reason to worry about their official classification - they can call them 'swamp gas' if they like...
This may be true, although some may contain heavier elements leftover from billion year old supernovas of the past. Honestly, I was giving some thought to the idea of possible binary systems containing stars like these that we simply haven't discovered yet. We do know that binary systems don't necessarily require the stars, or "star-like bodies" to be right atop one another. I think it would be very interesting to find a Y brown dwarf interlocked with a cool white dwarf, which would shower it with heaver elements. But who knows, our scientific community would probably just classify it as a gas giant planetoid with an unusual orbit. Who knows, there is so much about our universe(s) that is yet undiscovered. I would like to see the day in which we're able to detect the elusive & hypothetical "dark matter", only to find "dark life" along with it! Alas, that is doubtful in our lifetimes.
Reply | Report Abuse | Link to thisRegarding dark matter, I'm sorry to disappoint you, but no one has yet dissuaded me (and a few physicists) from thinking it was all just a mistake. Please refer to my previous comment for a more complete explanation:
Reply | Report Abuse | Link to thishttp://www.scientificamerican.com/article.cfm?id=ordinary-geniuses-book#comment-01
But jtdwyer, aren't we talking about "dark matter" here? Cooler than the human body? Who's to say objects can't exist at all temperatures down to three degree background radiation, and any mass less than a black hole? Instead of a gas body, why wouldn't it eventually be solid, maybe iron from a used up star? At cosmic distances, why isn't "dark matter" simply something that doesn't glow in a wavelength where we can differentiate it, and isn't close enough to something glowing for us to detect reflected life? What's the big mystery about it?
Reply | Report Abuse | Link to thisConsidering the possible number of very dark bodies out there, is it any wonder that we haven't been visited by ET?
Please copy responses to danrob@efn.org
See? I told you! Nemesis is out there, as cold and invisible as I've been tellin' ya! It's coming to get us, and we won't see it coming! (Do I need to rise the JK sign here?)
Reply | Report Abuse | Link to thisThe formation criteria for brown dwarves vs. gas giants seems confusing (and iffy) to me. But hey, I agree with jtdwyer in that they can call them what they want...
A good point is, how much of "dark matter" is actually cold and unlit "normal" matter that we're just missing? Seems much more likely to me than all this hoccus-poccus with dark particles. After all, we keep finding out that 'There are older and darker things than Orcs in the deep places of the world' and of space, too.
The requirements for dark matter necessary to produce the observed galaxy rotational characteristics, incorrectly presuming that Kepler's laws of planetary motion apply to spiral galaxies, is that an enormous mass extends far beyond the boundaries of the visible galaxy. Please see
Reply | Report Abuse | Link to thishttp://www.eso.org/public/images/eso1217b/
Discrete objects of non-luminous matter in an enormous enveloping halo would each gravitationally interact with ordinary stars at the galactic periphery - an effect that is not observed.
Most critically, an enormous galactic halo of discrete, non-luminous objects of mass would be illuminated by nearby and background energetic EM emissions from supernovae and AGNs, etc. That is why mysterious forms of dark matter are thought to consist of unidentified special particles that, in addition to not emitting EM radiation, for some reason do not interact with EM radiation. Non-luminous object composed of 'ordinary' matter could not meet these requirements.
Also, please refer to my brief commentary:
Reply | Report Abuse | Link to thishttp://www.sciencewithoutfiction.com/uploads/JDwyer.PDF
It includes several (of many) references to supporting research reports produced by qualified physicists.