[Space] star radius

[whswhs]

Originally Posted by Agemegos

The ideal thing to do would be to calculate the maximum luminosity and radius of the star at its red giant maximum, remove everything that is inside it, generate the whole system by calculating all the planets' and moons' black-body temperatures from combined insolation at their closest approach to the red giant, add the effect of the immense solar winds during the formation of the planetary nebula. Then alter the orbits, calculate the luminosity of the white dwarf, calculate the new values of insolation and black-body temperature, adjust the atmosphere types and masses to account for anything that condenses or freezes out, and calculate the new surface temperature.

I did most of that, after starting by creating a planetary system for the star's Main Sequence period. But I'm not sure how you figure the effects of the solar winds. Are we talking about solar winds during the star's expansion to red giant maximum?

[Agemegos]

Originally Posted by whswhs

I did most of that, after starting by creating a planetary system for the star's Main Sequence period. But I'm not sure how you figure the effects of the solar winds. Are we talking about solar winds during the star's expansion to red giant maximum?

I was thinking more of the asymptotic-branch red giant phase, during which a dying star sheds 50–70% of its mass in its solar wind, thus producing a planetary nebula.

[Keysh]

Originally Posted by AlexanderHowl

Pulsar planets are most likely captures (they are too close to have formed at their current radius, and the loss of mass during a supernova would have had any surviving planetary cores migrate outwards rather than inwards). The few planets we have found around white dwarfs are likely captures as well.

A paper from 2016 looked at possible formation mechanisms for pulsar planets. From the astrobites summary of that paper:

Out of the five pulsar planets known, the authors believe that the three planets in the PSR 1257+12 system were formed from the disk of a disrupted star, the planet orbiting PSR J1719-1438 is the core of an evaporated white dwarf, and the planet around PSR B1620-26 was captured along with its white dwarf, with the planet now orbiting both of them as a circumbinary planet.