More Trappist-1 constraints

On the (excellent) assumption that Trappist-1's planets are all differentiated, Emeline Bolmont, Alex Revol et al. offer "Estimation of the tidal heating in the TRAPPIST-1 planets". They are admittedly constrained by the uncertainty of what these planets' cores actually be, that Love Number we'd noted here once.

Also they don't know the eccentricities of b or c. Frankly I doubt they're Keplerian, so they need some postLaplacian model. Eccentricity tides would bump up their estimates especially inward.

What Revol (especially) thinks he does know, are the obliquity and the libration of each planetary rotation: less than one degree, each. But Revol does not hold these planets as tidally locked: a slow drift of the substellar point, which therefore leads to a day-night cycle.

I find intriguing this space elevator design for e. However Revol argues that the rotations for all planets are slow such that day/night appears retrograde. GEO is, then, high. Where GEO extend past Hill, all space elevators must be floating tether.

Even with low eccentricity it came out that b and c are superheated like Io (if not technically lava); it's elsewhere been noted they've lost everything volatile by now and are airless like Io. Planets d, e, f get more internal heat than Earth; e, they submit, may have a crust and plate tectonics. And we hear e has air. Although I am still not hopeful for photosynthetic life.

Kleisioti et al. move on to f, g, h asking after ice shells, quite reasonable for these cold planets with, further, lower measured density. Planets f and g might have thin Enceladus-tier ice shells; h's would be thick like Europa's. They think possible for us detecting cryovolcanically generated water vapor on f (maybe g) for which we haven't looked. 20 transits should do for seeing it on f.