points by njarboe 3 years ago

This seemed off the me also. Reading through the paper quoted in this sentence makes it clear that the sentence is just wrong. From [1]:

"The team found that planets 10 times the mass of the Earth, with an atmosphere 100 to 1000 times thicker than Earth’s, may be the most favorable for storing life for billions of years. But to do this, they must orbit the star at a distance that the orbit of Mars occupies in the Solar System. At such a potentially safe distance, the original atmospheres can act as greenhouse gases, absorbing infrared radiation, providing the necessary heat and pressure that can support life in oceans of liquid water."

So the planet is not ejected from the system, just pushed out so that instead of an orbit of days it is as far away as Mars is to our sun (1.5 AU). Gell-Mann Amnesia comes into play here.

[1] https://universemagazine.com/en/life-on-super-earths-can-exi...

divbzero 3 years ago

Thanks for spotting that link.

Digging one link farther reveals the original article [2] which is more detailed and descriptive than the others. The original article explores super-Earths where the primordial H–He atmosphere is retained and traps enough heat to sustain liquid water, and includes simulations of “unbound” super-Earths that are ejected from their star systems. The mathematical model [3] incorporates the initial heat from planet formation and radiogenic heat but does not mention tidal forces.

[2]: https://www.nature.com/articles/s41550-022-01699-8

[3]: https://github.com/mollous/Data_Liquid_Water_Conditions

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The original article also includes this discussion of habitability:

Life on the type of planet described in this work would live under considerably different conditions than most life on Earth. The surface pressures in our results are on the order of 100–1,000bar, the pressure range of oceanic floors and trenches. There is no theoretical pressure limit on life, and some of the most extreme examples in Earth’s biosphere thrive at ~500bar. These habitats also receive a negligible amount of direct sunlight, and therefore photosynthesis would not be an optional mechanism to provide for metabolism. Chemoautotrophic life on Earth would be a more likely analogue to possible life on this type of planet.

ReptileMan 3 years ago

Just to point that water is almost exactly 1000 times thicker than air Edit: 800 times if we have to be precise