Tuesday, November 7, 2023

Gliese 357's consolation-prize

We got copious bad news in from UCR last week; we'll deal here with that from GJ 357. Its innermost planet transits. There were some that hoped so did c and d - constraining their masses. But c and d do not transit.

If c and d are inclined relative to b, and to us, then their masses are large. On assumption of a large inclination and mass, c runs well over 3.4 Earth masses and d over 6.1. Planet d, at 0.204 AU, messes with this M system's (tight) habitable-zone. I don't think there is any question of decent moons or Trojans down there.

But hey - M stars suck anyway.

Stephen Kane and (here) his coauthrice, Tara Fetherolf, are looking 'pon the bright (and hot) side: c. This one gets 4.45 Earth flux means 2.34 Venus flux. This is still less than Mercury's, and c is much heavier than Venus besides. So c has likely retained its atmo. This hellworld might be worth a space-based mid-infrared low-resolution spectrograph.

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