massive gravity effects

[OneTrikPony]

Thank you Spirochete.
VERY cool of you to reply and help me out. I wasn't getting sensible results just by plugging in 3-G and random density to find Radius. 22000km is more interesting than 30000km. Hopefully I'll be able to learn to use the equations by plugging in your numbers.

This is the upper limit for a solid silicate-nickle-iron exoplanet. The minimum molecular weight retained is less than 2, meaning it retains hydrogen in its atmosphere. Since protoplanetary nebulae contain huge amounts of hydrogen, you'll need some explanation for the mechanism by which King escaped snowball accretion into a gas giant.

Where did you learn this? I'm not sure this is something I could have figured out by surfing wikipedia.
I'd like to be able to gather these facts for myself.

On the otherhand It seems, (from reading wikipedia) that DM+2 3312 must have been much hotter at some point because the stats from the book give it a temperature under the threshold for a K class star. Also it seems that during the preplanetary nebula phase the star's temperature is boosted to 30000K and there is a strong solar wind.

So, might King have had all it's hydrogen blown away during this phase, given that it's only .2 AU from it's sun?

 

[Wil Mireu]

Where did you learn this? I'm not sure this is something I could have figured out by surfing wikipedia. I'd like to be able to gather these facts for myself.

Funnily enough, the original 2300AD itself was a good introduction to the concept of MMW (minimum molecular weight) for most of us . It had detailed (and still reasonably realistic, compared to Traveller) world generation rules that went into this.

 

[spirochete]

Thank you Spirochete.
VERY cool of you to reply and help me out.

Anytime

I wasn't getting sensible results just by plugging in 3-G and random density to find Radius. 22000km is more interesting than 30000km. Hopefully I'll be able to learn to use the equations by plugging in your numbers.

Just remember, the units are "earths", where earth = 1 for any of the variables.

Where did you learn this?

I don't remember. I *do* remember the MMWR is generally proportional to the radius of a planet and inversely proportional to its mass, e.g., a planet with twice the mass-radius ratio as Earth retains molecules two times lighter than in Earth's atmosphere. A planet with half the mass-radius ratio retains gases two times heavier than Earth (for the same exobase altitude and temp).

Earth's exobase temp @ 600 km is ~ 1275 K and MMWR (for Jeans escape only) = 9.9 g/mol

Say King's M-R ratio is 5.571 = 10 earth masses / 1.795 earth radii.
So 9.9 g/mol divided by 5.571 = MMWR 1.777 g/mol approximately.

For more precise results, you need to calculate the escape velocity at the planet's exobase altitude and compare it to the mean kinetic velocity of various gas species at that altitude - a task best done with a spreadsheet. Mass-Radius ratio is much easier and almost as accurate.

I'm not sure this is something I could have figured out by surfing wikipedia.
I'd like to be able to gather these facts for myself.

A lot of world-building info is on Wikipedia, a whole lot more of it isn't. That's what the forum is for

On the otherhand It seems, (from reading wikipedia) that DM+2 3312 must have been much hotter at some point because the stats from the book give it a temperature under the threshold for a K class star. Also it seems that during the preplanetary nebula phase the star's temperature is boosted to 30000K and there is a strong solar wind.

So, might King have had all it's hydrogen blown away during this phase, given that it's only .2 AU from it's sun?

Possibly. Protosuns are quite violent and its conceivable that the T-Tauri winds blew away much of the lighter gases as King was forming.