Exoplanets: 30 Years Since Wolszczan-Frail...

[DEWLine]

Yes, it's been that long since that research paper got published.

https://twitter.com/DaleFrail/status/1480159110725308416

 

[Tim Walker]

As I recall, the pulsar planets were very unexpected. It had been assumed that our own solar system was fairly typical.

 

[Asbo Zaprudder]

Has anyone come up with a good theory of how pulsar planets can exist at all? A star going supernova would likely destroy any existing planets or throw them out of orbit due to the mass lost by the star exploding. I suspect it's possible that planets might form from metal-rich debris as the pulsars 4U 0142+61 and possibly 1E 2259+586 have circumstellar disks.

 

[shapeshifter]

I think you answered your own question but, they grow from the remaining debris?

 

[Asbo Zaprudder]

I think you answered your own question but, they grow from the remaining debris?

Yeah, I couldn't come up with anything else other than some very large planets might not quite achieve escape velocity from the system and their cores survive. However, planets forming from the debris seems possible given there are a couple of pulsars that probably have discs of material around them. The time period required to form planets from such a disc is of the same order of magnitude as the lifetime of a pulsar before its radio emissions turn off - between 10 million and 100 million years - so it's a reasonable scenario.

Here's a crazy thought - perhaps large planets that become gravitationally unbound from stars that go supernova and which manage to survive the blast end up becoming the seeds of new star formation as they travel through molecular clouds.

 

[publiusr]

A dying star swells…and the drag causes the planets to move inward…charred to their iron cores from the blast…they remain…at least as building blocks.

 

[Asbo Zaprudder]

If the star loses more than 50% of its mass in the explosion, all the planets achieve escape velocity by dint of their prior orbital velocities. Escape velocity is √2 times orbital velocity and stable orbital velocity is proportional to the square root of the star's mass so the mass has to decrease by a factor of 2. Massive stars generally lose much more than 50% of their mass in a supernova. Stars heavier than about 25 solar masses might lose this much mass just by the enhanced stellar wind near the end of their life.

Relationship between Escape Velocity and Orbital Velocity (collegedunia.com)
astrophysics - How much mass is typically ejected from a supernova? - Physics Stack Exchange
Presupernova evolution and explosion of massive stars Marco Limongi and Alessandro Chieffi 2010 J. Phys.: Conf. Ser. 202 012002

 

[Tim Walker]

Would anybody be interested in a general purpose Exoplanet thread?

 

[Asbo Zaprudder]

This thread probably suffices. It'll be a while before the Webb provides interesting results and there's my thread on unexplained astronomical observations for discussion of weird transit data.

 

[XCV330]

on the subject of planetary pulsars, this paper is interesting:
https://ui.adsabs.harvard.edu/abs/1995Ap&SS.227..229H/abstract

just a small hypothesis, assuming that stellar pulars are indeed a variety of neutron star, planetary pulsars could be something quite different, possibly super-jupiters or even methane brown dwarfs with very strong magnetospheres orbiting stars with likewise strong magnetospheres, the fields interacting and pulsing at frequency. anyway, just a shot in the dark.