Solar Mass, Radius and the AU

Rardain

Rardain
Having played the game for a fair old while now I find I am becoming interested in the astronomical information of the various systems I am exploring. With this in mind I wondered if someone could tell me what a stars Solar Mass and Radius measurements are related to and what the Semi-Major Axis is?

I have an idea that the mass and radius use Sol as the baseline.

If this is the case then for example a star with a Solar Mass of 1.0664 and a Solar Radius of 1.0824 is just slightly bigger and heavier than Sol...is this correct?

The AU (Astronomical Unit) is a measurement derived from the average distance between the Earth and Sol - approximately 93 million miles. Can anyone tell me what the Semi-Major Axis of a star is as this is measured in AU's.

Cheers

Cy
 

Ceekay

Ceekay
No expert on astronomical stuff but I think the Semi-Major Axis refers to the stars orbit as when it's in the planetary data it would give the max distance away from the emergence point to the station orbiting that planet.
 

Zenith

Zenith
You're right.
Mass and radius are multiples of the mass of Sol, our closest star.
1AU is approximately 500ls (give or take). The semi-major axis measurement is the average distance of the planet from the star. So multiply the number of AUs by 500 to get an estimate of it's travel distance in ls.
Using that distance information, you can also take a reasoned guess at whether a planet is simply a rock or if it is a terraform candidate. Each star has a "Goldilocks zone" for water. For our own solar system it is just about the orbit of Venus to the orbit of Mars. Earth is slap bang middle of it for Sol. If you see a water world 1AU/500ls from a G2 star, it will likely be a terraform candidate (if not an Earth-like world) because it is within the right temperature range for liquid water.
Stars go from F to G to K to M getting cooler as they go. 1AU is sweet for a G star, but might be too close for an F star, and too far for a K star.
 

Varrag

Varrag
ellipse_major_axis.png

Semi-major axis is the average distance of celestial body from the host star; for Earth it's 1 AU (~150 million km).
 
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