Alien Life Could Thrive In the Clouds of Failed Stars (sciencemag.org)

sciencehabit writes: There's an abundant new swath of cosmic real estate that life could call home -- and the views would be spectacular. Floating out by themselves in the Milky Way galaxy are perhaps a billion cold brown dwarfs, objects many times as massive as Jupiter but not big enough to ignite as a star. According to a new study, layers of their upper atmospheres sit at temperatures and pressures resembling those on Earth, and could host microbes that surf on thermal updrafts. The idea expands the concept of a habitable zone to include a vast population of worlds that had previously gone unconsidered. "You don't necessarily need to have a terrestrial planet with a surface," says Jack Yates, a planetary scientist at the University of Edinburgh in the United Kingdom, who led the study. Atmospheric life isn't just for the birds. For decades, biologists have known about microbes that drift in the winds high above Earth's surface. And in 1976, Carl Sagan envisioned the kind of ecosystem that could evolve in the upper layers of Jupiter, fueled by sunlight. You could have sky plankton: small organisms he called "sinkers." Other organisms could be balloonlike "floaters," which would rise and fall in the atmosphere by manipulating their body pressure. In the years since, astronomers have also considered the prospects of microbes in the carbon dioxide atmosphere above Venus's inhospitable surface. Yates and his colleagues set out to update Sagan's calculations and to identify the sizes, densities, and life strategies of microbes that could manage to stay aloft in the habitable region of an enormous atmosphere of predominantly hydrogen gas. On such a world, small sinkers like the microbes in Earth's atmosphere or even smaller would have a better chance than Sagan's floaters, the researchers will report in an upcoming issue of The Astrophysical Journal. But a lot depends on the weather: If upwelling winds are powerful on free-floating brown dwarfs, as seems to be true in the bands of gas giants like Jupiter and Saturn, heavier creatures can carve out a niche. In the absence of sunlight, they could feed on chemical nutrients. Observations of cold brown dwarf atmospheres reveal most of the ingredients Earth life depends on: carbon, hydrogen, nitrogen, and oxygen, though perhaps not phosphorous.

Comments

Re:But what would they eat?

[wierd_w]

I see that the ACs are idiots, as usual.

The brown dwarf does not really have fusion at its core, but it does have fission. (It is heavy, and absorbs heavy atoms from the nebular cloud it forms from, which settle to its core.) This heats the brown dwarf internally, causing convection.

This supplies energy, and a weather system that will move raw materials around inside the brown dwarf. Dead microbes will be subducted deeper into the brown dwarf, become denaturated from the heat, and become raw materials. Those will be pushed up by convection.

In addition to heat, brown dwarfs DO emit light from blackbody radiation, and being pretty damned hot down there (just not enough for fusion), that is quite a bit in the visible spectrum. That means photosynthetic life can persist in the temperate layers high up.

So, what do they eat?

1) chemicals replenished by denaturation deeper inside the star.
2) Light emitted from deeper inside the star.
3) each other.

Re:But what would they eat?

[wierd_w]

Here genius, because you are clearly an idiot.

Chemotrophs get energy by ingesting electron donating chemical substances, which gives them the energy they need for respiration.

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

Heterotrophs consume other organisms to gain their energy for respiration.
https://en.wikipedia.org/wiki/...

Autotrophs are able to absorb inert substances, and combine them with some form of radiant or abmient energy, and turn them into lower entropy food supplies that they use to power respiration.
https://en.wikipedia.org/wiki/...

So, again-- the answers are:

1) chemicals
2) each other
3) light