Possibility of life around Brown dwarfs? 3 possible planets found to be potentially Earthlike

[Spaceception]

A few years ago, I didn't think that brown dwarfs were interesting, but a few months ago, I've started to become quite fond of them.

• Anyway, what kind of life could take hold on brown dwarfs? I believe they would rely on the infrared spectrum, but what other properties would it have?
• Do brown dwarfs have a habitable zone? I mean, they have temperatures of 2000 k upwards. How big is it? and how long would it last?
• How long would the possible life be able to live before the brown dwarf cooled to the point of any possible planets freezing over?
• What's the minimum size for a brown dwarf containing life bearing planets?

https://en.wikipedia.org/wiki/Brown_dwarf

Pics below from Space Engine! (Google images ftw!!)

Spoiler

 

Edited May 2, 2016 by Spaceception

[Spaceception]

More info on Brown dwarfs, as well as a list of all of them within 43 ly.

http://www.solstation.com/stars/pc10bd.htm

And a video hosted by Badastronomer;

 

Edited April 27, 2016 by Spaceception

[kerbiloid]

Habitable zone.

r = 70000 km = 7e7 m
T = 2000 K

L = 4 * pi * 7e7^2 * 2000^4 * 5.67032e-8 = 5.6e22 W
L/Lsun ~= 1.5e-4

[Jones' method]

S1(2000 K) = 1.0358
S2(2000 K) = 0.2361

R1 = sqrt((L/Lsun) / S1)) = sqrt(1.5e-4 / 1.0358) ~= 0.012 AU
R2 = sqrt((L/Lsun) / S2)) = sqrt(1.5e-4 / 0.2361) ~= 0.025 AU

According to formula for tidal lock, any moon will become tidally locked very soon (years or less). So, tidally locked.

According to wiki/rus link ( http://adsabs.harvard.edu/full/2004IAUS..213..115A ), lifespan can be 10 bln years for 0.07 Msun dwarf and 4 bln years for 0.04 Msun.

Edited April 28, 2016 by kerbiloid

[Spaceception]

4 hours ago, kerbiloid said:

Habitable zone.

r = 70000 km = 7e7 m
T = 2000 K

L = 4 * pi * 7e7^2 * 2000^4 * 5.67032e-8 = 5.6e22 W
L/Lsun ~= 1.5e-4

[Jones' method]

S1(2000 K) = 1.0358
S2(2000 K) = 0.2361

R1 = sqrt((L/Lsun) / S1)) = sqrt(1.5e-4 / 1.0358) ~= 0.012 AU
R2 = sqrt((L/Lsun) / S2)) = sqrt(1.5e-4 / 0.2361) ~= 0.025 AU

According to formula for tidal lock, any moon will become tidally locked very soon (years or less). So, tidally locked.

According to wiki/rus link ( http://adsabs.harvard.edu/full/2004IAUS..213..115A ), lifespan can be 10 bln years for 0.07 Msun dwarf and 4 bln years for 0.04 Msun.

So long enough to have intelligence develop?

[kerbiloid]

10 minutes ago, Spaceception said:

So long enough to have intelligence develop?

With such low luminance and soft infra-red light the photosynthesis would be ve-ery slow and weak.

So, not many chances.

P.S.
But probably great to cultivate mushroom plantations if create them artificially.

Edited April 28, 2016 by kerbiloid

[Tex_NL]

You do not need photosynthesis for life. Chemosynthesis will do just fine. And tidal friction is an excellent energy source. There are plenty of examples how life can flourish near geothermal vents in complete darkness.

So is life possible around brown dwarfs? Absolutely! It might not be life as we know it but it IS possible.

Edited April 28, 2016 by Tex_NL

[Spaceception]

1 minute ago, Tex_NL said:

You do not need photosynthesis for life. Chemosynthesis will do just fine. And tidal friction is an excellent energy source. There are plenty of examples how life can flourish near geothermal vents in complete darkness.

So is life possible around brown dwarfs? Absolutely! It might not be life as we know it but it IS possible.

Would life as we know it be possible? Or maybe could our life adapt to the dimmer light of a brown dwarf then?

[Tex_NL]

9 minutes ago, Spaceception said:

Would life as we know it be possible? Or maybe could our life adapt to the dimmer light of a brown dwarf then?

No idea, I am no xenobiologist. I am just an everyday schmuck with an above average IQ. But if life on earth has proven one thing is that it is extremely resilient and adaptable as long as the changes to its environment are slow and gradual. Transplanting surface life from earth to an alien planet under a brown dwarf would probably kill it. But if you take the deep sea life that is currently thriving near geothermal vents without any sunlight it should probably be OK as long as the chemistry is similar.

[kerbiloid]

1 hour ago, Tex_NL said:

Chemosynthesis will do just fine.

Well, they'll have enough mildew. Absolutely different energy values. Direct sunlight converted into organics vs multi-(dozen)-stage scalding.

1 hour ago, Tex_NL said:

But if you take the deep sea life that is currently thriving near geothermal vents without any sunlight it should probably be OK as long as the chemistry is similar.

This life eats organic remains sinking down from the surface where they appear due to photosynthesis.

Chemosynthetics are just puny bacteria living in a permanent stress.

Edited April 28, 2016 by kerbiloid

[Andem]

2 hours ago, Spaceception said:

Would life as we know it be possible? Or maybe could our life adapt to the dimmer light of a brown dwarf then?

Depends on your definition of "Life as we know it". Animals like cats and dogs are unlikely, as creating a stable food chain would be extremely difficult with so few energy sources. Most likely life forms would be somewhere between plants and animals, like a fungus that has orifices for ingesting any small creatures, like a venus flytrap.

[Elukka]

I don't see why it would be so energy-limited. You'd have about as much sunlight as we do on Earth, just longer wavelength. We have organisms on Earth that can photosynthesize in the near-infrared, and that would be much more heavily selected for around a low mass brown dwarf. There will also be visible light. Maybe you'd have somewhat less energy to go around particularly on low mass dwarves compared to Earth but I don't see why you wouldn't have enough for an energy-rich ecosystem based on photosynthesis.

Edited April 28, 2016 by Elukka

[Andem]

31 minutes ago, Elukka said:

I don't see why it would be so energy-limited. You'd have about as much sunlight as we do on Earth, just longer wavelength. We have organisms on Earth that can photosynthesize in the near-infrared, and that would be much more heavily selected for around a low mass brown dwarf. There will also be visible light. Maybe you'd have somewhat less energy to go around particularly on low mass dwarves compared to Earth but I don't see why you wouldn't have enough for an energy-rich ecosystem based on photosynthesis.

Well, this post above yours:

9 hours ago, kerbiloid said:

With such low luminance and soft infra-red light the photosynthesis would be ve-ery slow and weak.

So, not many chances.

P.S.
But probably great to cultivate mushroom plantations if create them artificially.

So, I then arrive at the hypothesis:

2 hours ago, Andem said:

Depends on your definition of "Life as we know it". Animals like cats and dogs are unlikely, as creating a stable food chain would be extremely difficult with so few energy sources. Most likely life forms would be somewhere between plants and animals, like a fungus that has orifices for ingesting any small creatures, like a venus flytrap.

 

Edited April 28, 2016 by Andem

[Kryten]

4 hours ago, kerbiloid said:

This life eats organic remains sinking down from the surface where they appear due to photosynthesis.

Chemosynthetics are just puny bacteria living in a permanent stress.

That's true for most deep-sea areas, but hydrogen sulfide-rich vents provide a pretty comfortable habitat for chemosynthetic micro-organisms, to the extent they have macro-scale symbionts, like the famous geothermal tube worms or yeti crabs. You get similar results at sites where hydrocarbon reservoirs are leak into the ocean (cold seeps), except with the chemosynthetic organisms using methane.

[kerbiloid]

5 hours ago, Kryten said:

but hydrogen sulfide-rich vents provide a pretty comfortable habitat for chemosynthetic micro-organisms, to the extent they have macro-scale symbionts

Hardly.
Chemically, Sulfur is an analog of Oxygen — and it's an effective oxidizer, of course, and H₂S is analog of H₂O - and it's an effective solvent. This allows sulfur / H₂S-based life to exist.
But the solvent must be liquid — while the oxidizer must be liquid or gaseous. None of them would be solid.
 

Substance	Melting point, K	Boiling point, K
Oxygen	54	90
Sulfur	388	718
H2O	273	373
H2S	191	213

So, as you can see, when H₂O (a solvent) is liquid, Oxygen (an oxidizer) is gaseous, and it's well soluble in H₂O.

When H₂S is liquid, Sulfur is solid - and strongly solid, much below its melting point, When Sulfur is at least liquid, H₂S is an overheated gas.
So the only way for a sulfur-base life to exist: hight temperature and high pressure — when it's enough hot for Sulfur to be liquid, while the pressure is enough high to make the overheated H₂S to stay liquid.

So, all known (and probably the only possible) sulfur-based lifeforms are bacteria-extremophiles, living either in underground thermal pool or in underwater volcanos. This is a very extremely stressed habitat.
Proteins usually begin to denaturate at 315-320 K, which is much lower than the melting point of Sulfur. In fact, sulfur-based bacteria are surviving in a sterilization box.

So, it's hard to imagine how a sulfur life can evolve into something more complicated than a sponge.

Edited April 29, 2016 by kerbiloid

[kerbiloid]

7 hours ago, Elukka said:

You'd have about as much sunlight as we do on Earth, just longer wavelength. We have organisms on Earth that can photosynthesize in the near-infrared

To activate photosynthesis reaction you need a photon with energy enough high for ionization.

From the opposite side, its energy would be not too high — to not ionize all around. UV photons crash all around, so white/blue star specters are hostile and dangerous for life.

But the weaker is photon — the less is probability that it can ionize something and start a photosynthetic reaction.
The Sun specter photons are near optimum: enough powerful, but not overpowered.

The lower is probability of photosynthetic reaction — the more photons are lost as a heat.
So, the more "infrareder" the light — the less part of photons run photosynthesis — the slower is chemical energy accumulation — the lower is "edible energy" density per surface area — the less food — the more anemic and less numerous beings. Sleepy crawlers crawling to "catch" herbovorous crawlers, or so.

As an example: a tiny tropical snake can kill with one bite, while the nothern vipers must bite by three of them just to be noticed. Poison production requires energy.

 

Btw, as brown dwarfs are convective through all their volume, we can presume that temperature (and weather) conditions are pretty unstable on its closest satellites.

 

Edited April 29, 2016 by kerbiloid

[daniel l.]

A large brown dwarf is better for life than a small red dwarf, The Roche limit on a small red dwarf is surrounding the habitable zone meaning an earthlike planet in the zone would tidally break up. A large brown dwarf doesnt emit as much light but the heat it emits is enough to support a world outside the Roche limit.

[Kryten]

7 hours ago, kerbiloid said:

Chemically, Sulfur is an analog of Oxygen — and it's an effective oxidizer, of course, and H₂S is analog of H₂O - and it's an effective solvent. This allows sulfur / H₂S-based life to exist.

I've snipped the rest of this post because it's based on this premise, which is fundamentally wrong. I'm not talking about hydrogen sulphide as a replacement for oxygen as an electron acceptor, or hydrogen sulphide as a solvent, just hydrogen sulphide as an energy source.

[kerbiloid]

2 hours ago, Kryten said:

I've snipped the rest of this post because it's based on this premise, which is fundamentally wrong

Read periodic table, please.

[Kryten]

Just now, kerbiloid said:

Read periodic table, please.

It's irrelevant if you're looking at the wrong chemical processes, which you are.

[kerbiloid]

1 minute ago, Kryten said:

It's irrelevant if you're looking at the wrong chemical processes, which you are.

Oxygen 1s²2s²2p⁴
Sulfur 3s²3p⁴

 

[Kryten]

And for the second bloody time, I'm not talking about sulphur as an electron acceptor, but as an energy source. The organisms I'm talking about still use oxygen as the final electron acceptor.

[kerbiloid]

2 minutes ago, Kryten said:

And for the second bloody time, I'm not talking about sulphur as an electron acceptor, but as an energy source. The organisms I'm talking about still use oxygen as the final electron acceptor.

Then you probably can explain how an oxygen atmosphere can co-exist with "energetical" amounts of H₂S.

[Kryten]

17 minutes ago, kerbiloid said:

Then you probably can explain how an oxygen atmosphere can co-exist with "energetical" amounts of H₂S.

I could, but then you'd find a whole bunch of other 'problems' and it'd be a waste of my time. You realise I'm describing real animals here? You're acting like giant tubewroms and co. and the basis for their metabolism cannot exist, when they demonstrably do. This is not a hypothetical scenario that I need to defend, and there's plenty of literature available on how they work.

[kerbiloid]

49 minutes ago, Kryten said:

real animals

Sulfate-reducing bacteria are anaerobic.

[Kryten]

Just now, kerbiloid said:

Sulfate-reducing bacteria are anaerobic.

I'm not talking about them, for the third bloody time. That's use of sulphate as terminal electron acceptor, I'm talking about sulphur-oxidising bacteria that use oxygen as terminal electron acceptor.

 

Look, here's a fully open-access and pretty clearly-written article on exactly how the relationship between giant tubeworms and their symbiotes works. Please at least try to read it before asking more questions.