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Fraser
2005-Oct-21, 03:22 AM
SUMMARY: NASA's Spitzer Space Telescope has spotted what could be the early stages of planets forming around a failed star. The infrared telescope detected clumps of microscopic dust grains and tiny crystals orbiting five brown dwarfs. Similar material has been seen around other newly forming stars and in our own Solar System. Despite being colder and smaller than stars like our Sun, it appears that brown dwarfs still undergo many of the same stages, including the construction of planets.

View full article (http://www.universetoday.com/am/publish/planets_common_dwarfs.html)
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Planetwatcher
2005-Oct-21, 05:44 AM
Which are the 5 brown dwarfs with planets?

It does make since that even brown dwarfs could have planets.
Even if brown dwarfs don't begin a fussion reaction, that really isn't a factor for planets.
In fact if one really thinks about it there is no reason why planets couldn't form around any kind of steller body. Planets have moons, even asteroids have moons. And what are moons but natural satelites of planets. And planets in turn are natural satelites of stars. So what is the difference a moon orbiting a planet, or a planet orbiting a star? None really. Except for the parent body.

Greg
2005-Oct-21, 06:05 AM
I guess the thinking was that if a cloud did not have enough material to form a star big enought to begin fusion, then that cloud wouldn't have enough material in it to form planets either.
The other thinking was that brown dwarfs may form differently than typical stars.
Either way the thinking went that if a star could not form, then the starting conditions must therefore preclude planet formation as well.
That kind of thinking now seems overly simplistic and inherently biased by what we knew about our own solar system.
The bad news is that these systems would not be habitable by our standards. A lack of sunlight emanating from these kind of stars would make these worlds dim places indeed. Although tidal heating may make them warm (and quite volcanically active,) a lack of sunlight means no photosynthesis and no possibility of an oxygen atmosphere by any means we know about.

suitti
2005-Oct-21, 05:34 PM
My guess is that the 'crystals' would be roughly spherical, after 1 to 3 million years of bumping into each other. The roughly spherical crystals would then act as retroreflectors. Then, there'd be a signature similar to zodiacal light.

Prove me wrong. Go out there and find out.

While not an expert on this subject, it seems that to get enough heat for liquid water, a planet would have to orbit pretty close to the brown dwarf. Some say that this close orbit would require a tide-locked arrangement. The argument then says that one side would be baked, and the other frozen. However, an atmosphere would transport heat to the far side. Living on the far side may not give you light for photosynthesis, but it might protect you from x-ray flares coming out of the brown dwarf.

Then, there's the idea of having a big moon. The planet would be tide locked to the moon. The planet/moon system might be resonance locked with the star - say 4 lunar orbits per year or something - which would be 4 days per year.

Life on Earth didn't start needing oxygen. Life produced oxygen as a waste product. It was a deadly posion. Life then evolved to consume it. There are other possible energy sources here on Earth. Methane eaters, sulfuric acid eaters, thermal vent denizens.

Life finds a way - Jurrassic Park.

Greg
2005-Oct-22, 03:30 AM
There could very well be life, but not an oxygen rich environment that we would need to survive. It would take a leap of imagination on how to generate significant oxygen in an atmosphere without photosythesis (as our friendly blue-green algae were the first to do), and in 2 billion years or so on Earth the abundant lifeforms were unable to do so. It would also be dimmer than a dungeon. Tidal heating could occur around a planet in close orbit to the brown dwarf or around a large moon near a gas giant in orbit. Europa may end up being a prototype for the kind of life one might find around such a dwarf. Of course we do not know whether life exists there or not. My suspicion is that some kind of primitive bacteria or equivalent life will be found beneath the ice there. It would have to be an extremophile since the ocean under Europa's ice would be highly saline and probably acidic as well.