TOI-1408

Don’t get attached to this system; it’s a F8V, already 2.7 Gy. It’ll redgiant before anything good evolves here. The paper announces a c, inbound of already-hot b. They are almost but not quite 2:1 resonance – they librate. Like that HD. Luminosity is 2.96, so a comfy (91% Earth) insolation could be had at 1.8 AU. It would have been cooler earlier but, as noted, the star is on the outs.

And there’s an outer:

?2530/365.256
6.9266487066605347
?Math.Pow(6.9266487066605347*6.9266487066605347*1.31, 1.0/3.0)
3.9759343688051021

Which we could round to 3.976 AU. 0.35 eccentricity means perihelion 2.584 AU. The 14.6 jove mass is a lower bound. But I do not know its inclination. It is hard to see how it could have got there naturally.

Overall this couple is the interesting part of the system – for its dynamics. I don’t know that these two could have migrated together. This suggests they formed here. Which has implications for other hot Jupiters. In particular if a hot Jupiter could form, and have a smaller planet beneath it; there could exist smaller planets still in-situ above it, as far as HZ, especially given the width of the HZ band.

But here the (probable) superplanet “d” could be sweeping the HZ of livable matter if an even bigger von Zeipel perturbator is out at “e”.