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Author Topic: Could life exist around a brown dwarf?  (Read 5323 times)

Offline kenhikage

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Could life exist around a brown dwarf?
« on: 05/10/2010 04:36:53 »
Can brown dwarfs support life?
Why aren't we looking harder for them?
« Last Edit: 05/10/2010 13:58:34 by kenhikage »


 

Offline syhprum

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Re: Could life exist around a brown dwarf?
« Reply #1 on: 05/10/2010 13:18:09 »
Although life is very versatile and exists in many unlikely niches I think life on a brown dwarf quite impossible, brown dwarfs are like a more massive version of Jupiter consist mostly of Hydrogen which is still at a high temperature due to the gravitational energy of their formation.
As one goes down thru this gaseous envelope one encounter ever increasing temperature's and pressure until at the core they may be high enough to allow some Deuterium's fusion reactions   
 

Offline kenhikage

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Re: Could life exist around a brown dwarf?
« Reply #2 on: 05/10/2010 13:58:12 »
Ah, I blundered in my question. I meant to ask, could a planet orbiting a brown dwarf support life?
 

Offline flr

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Could life exist around a brown dwarf?
« Reply #3 on: 05/10/2010 17:03:06 »

 The most likely place to find life on our solar system appear on the moon Europe that orbit Jupiter.
 
 I can imagine a similar scenario a brown dwarf might have life as following:
 1. A planet orbiting the dwarf on a sufficiently elliptic
 2. The difference in tidal forces (as a result of the slight elipticity of the orbit) will stretch and keep tectonics of the planet kind of moving and generating heat.
 3. If the heat is large enough, some kind of primitive bateria could be possible.   
 
 

Offline syhprum

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Could life exist around a brown dwarf?
« Reply #4 on: 05/10/2010 17:31:48 »
The chief obstacles to life evolving on the planet of a brown dwarf seem to be two fold, firstly the flares which they emit which could well mean that only sub aquatic life evolves and secondly their short life as they have only the heat generated by gravitational collapse and no fusion.   
 

Offline kenhikage

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Could life exist around a brown dwarf?
« Reply #5 on: 05/10/2010 18:16:21 »
I see. I didn't know they frequently flare. But, that abundance of hydrogen would mean water is likely, right? And there is heat generated, as low as it may be. So, a planet very near a brown dwarf wouldn't be a bad place to look?

Quote
2. The difference in tidal forces (as a result of the slight elipticity of the orbit) will stretch and keep tectonics of the planet kind of moving and generating heat.
So that would prevent tidal locking?
 

Offline Soul Surfer

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Could life exist around a brown dwarf?
« Reply #6 on: 05/10/2010 18:44:58 »
brown dwarfs are unlikely to flare because their only energy source is gravitational collapse but red dwarfs which are fusing nuclei often do.  The process is probably similar to solar flares with the sudden release of magnetic energy but the proportionate effect is much grater brightening the star by several magnitudes
 

Offline syhprum

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Could life exist around a brown dwarf?
« Reply #7 on: 05/10/2010 20:05:48 »
http://en.wikipedia.org/wiki/Brown_dwarf



See Brown dwarf as an X-ray source in this article.
« Last Edit: 05/10/2010 20:08:35 by syhprum »
 

Offline Soul Surfer

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Could life exist around a brown dwarf?
« Reply #8 on: 05/10/2010 22:14:55 »
Thanks for the reference.  It is quite clear that the possibility of magnetic flares should be extended downwards into brown dwarfs as well.  I must admit that I was having misgivings as I wrote it and was not fully aware of current work in this area.
 

Offline kenhikage

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Could life exist around a brown dwarf?
« Reply #9 on: 07/10/2010 15:22:05 »
And X-ray flares are damaging to life?
 

Offline Ophiolite

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Could life exist around a brown dwarf?
« Reply #10 on: 07/10/2010 17:01:07 »
And X-ray flares are damaging to life?
Very. Go ask your doctor to take three hundred chest X-Rays of you in quick succession and see how long you last.
 

Offline imatfaal

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Could life exist around a brown dwarf?
« Reply #11 on: 07/10/2010 17:22:57 »
Ionizing radiation can be dangerous - but depends on intensity.  I have struggled with maths and conversion of units; but my back of an envelope calculation suggests that intensity of the brown dwarf xray burst might be enough to cause widespread harm on a planet at one astronomical unit (about .75 joules/m2 accumulated over a period of 11 hours - with a peak rate of 5*10-4 joules/m2 per second). the safe doses of ionizing radiation are given in units of joules per kg of matter - and the conversion is far from obvious with other factors added.  5 gray (joules/kg) would be enough to kill - I don't think that form of x-ray burst would be nice
 

Offline syhprum

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Could life exist around a brown dwarf?
« Reply #12 on: 07/10/2010 19:23:18 »
Due to the low mass and modest temperature of brown dwarfs the Goldilocks zone is probably only 0.1 AU hence the intensity of Xray flares would be a hundred times greater.
Not a very comfortable environment.
 

Offline kenhikage

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Could life exist around a brown dwarf?
« Reply #13 on: 08/10/2010 11:34:29 »
Quote
Very. Go ask your doctor to take three hundred chest X-Rays of you in quick succession and see how long you last.
Yeah, but I would die from my DNA breaking down. Life isn't required to be built on DNA, is it?

I would assume that any life that would form around a brown dwarf would "see" or use x-rays as Earth-life sees and utilizes sunlight.
 

Offline imatfaal

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Could life exist around a brown dwarf?
« Reply #14 on: 08/10/2010 22:22:35 »
Ken - these are x-ray flares, 11 hours or so with years in between.  the life would need to be utilising every scrap of electromagnetic radiation (brown dwarves are pretty cool) - most of it would be much less energetic than xrays.  And without any knowledge (obviously, who could have) I would have thought x-rays would disrupt any lifeform adapted to survive on infrared and less energetic radiation.
 

Offline kenhikage

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Could life exist around a brown dwarf?
« Reply #15 on: 12/10/2010 05:36:27 »
Oh! I see. So, the majority of their energy is infrared, but occasionally there are x-ray bursts. That's not exactly intuitive, but now I think I understand. Our sun has a much smaller range between it's smallest and most extreme radiation than do brown dwarfs, right?
 

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Could life exist around a brown dwarf?
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