Gliese 1214

This blog hasn't touched the GJ 1214 system as yet. It looks like it's time.

The system is 48 light years away, in Ophiuchus behind Barnard's. The star is red dwarf. A transit dips into the light relative to us every 1.5804 days. No eccentricity, so we assume its planet is tidally-locked. If it be a "superEarth" it is a fluffy one: zero-albedo equilibrium temperature of ∼600 K, a radius of 2.7 R_⊕, and a mass of 8.2 M_⊕. So miniNeptune has been mooted - Sudarsky II, which is measured from kelvin (to my chagrin; we cannot talk of albedo a priori).

Everett Schlawin and Kazumasa Ohno, together with their harem of et al., are now telling us it is high in carbondioxide. They talk of "metallicity" which is a stellar term for anything not hydrogen or helium: our two ice-giants have eighty times our Sun's metallicity; miniNeptunes are more like a hundred (like GJ 3470 b or K2-18 b). For that, this GJ 1214 planet is more in the thousands. There's no hydrogen "hycean" layer; that element is bound up in molecules UPDATE 2/1 like methane.

They don't say outright, but with CO₂ this high, that fluffiness should be a cloud-deck with low water content; room-temperate acid would do. Gliese 1214 b is a superVenus. Like Aphrodite in that Gateway book; although the Heechee haven't been detected yet.

THAT METHANE 2/1: on review, I am curious how methane survived there and not down here on Venus. Something seems up with the magnetosphere of the star and how it interacts with this planet's core.