Monday, April 25, 2022

Goldilocks, or not

This just in, for Earth Weekend: "The Outer Edge of the Venus Zone", by Monica R. Vidaurri, Sandra T. Bastelberger, Eric T. Wolf, Shawn Domagal-Goldman, and Ravi Kumar Kopparapu. Missed the Appreciation Day by a... hair.

Overall, these five argue that runaway Venus can happen further into the habitable-zone than previously thought. Much then depends on the planet. This isn't well-constrained for Venus herself, although we're getting better. Of course for extrasolar planets this isn't constrained at all, although - they note - Webb will help.

I assume as rule-of-thumb that Venus will come for the heavier planets with presumably-thicker atmospheres of carbon, first. Especially if the water isn't there. Also I am unsure that these researchers should even have bothered with the M systems given that their "habitable" zone will be tidally-locked, and often subject to flare. Like Proxima next door.

One strike of bad news falls upon the K systems with their presumed "Goldilocks" planets. K (and M) delivers more radiation into the infrared which is exactly what a greenhouse will trap: K5V (0.70 M) is 0.68 AU. UPDATE 10/8: If the orbit and rotation are in a Mercury resonance then its planet is basically a rotisserie.

COLD WATER 10/12 Ethan Siegel. NO PLANTS 3/5/23 Spectra.

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