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Old 01-11-2020, 11:41 AM   #8
whswhs
 
Join Date: Jun 2005
Location: Lawrence, KS
Default Re: [Space] star radius

Here is a bit from my Pyramid article Omicron Polypi. I did the analysis in 2006 but the article file is dated 2009; I assume it was published in that time range.

Over the course of its lifetime, Omicron Polypi B went through several stages with different luminosities. As a main sequence star and a subgiant, it had luminosity 4.5. When it became a giant, its luminosity was 25 times as high, or 112.5. Now, as a white dwarf, it has luminosity 0.001.

This drastically altered the conditions on all of its planets. But the changes were biggest on its third planet, Hector.

Hector is a large planet, orbiting 0.77 AU from its star. During Omicron Polypi B’s early life, this gave it a blackbody temperature of 462 K, which made it a greenhouse planet. But when Omicron Polypi B became a giant, Hector’s blackbody temperature rose to 1,032 K, well into the chthonian range. The intense heat drove away Hector’s atmosphere, leaving it with only a trace of gases replenished by solar wind. At the same time, much of Hector’s crust melted. Then Omicron Polypi B diminished to a white dwarf, dropping Hector to its current blackbody temperature of 56 K. Normally this would make it an ice world, but with its atmosphere already driven off, it has nothing to form ice with. Instead it becomes an anomalously cold rock world. The other planets that orbit Omicron Polypi B had comparable, but less extreme histories because of their lower mass.
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Bill Stoddard

I don't think we're in Oz any more.
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