Proposed cool stars temperatures update

[onetwothree]

Here: https://github.com/CelestiaProject/Celestia/pull/563/files

Any comments? Any objections?

[Lafuente_Astronomy]

I'm no master on Star Temperatures but did you use accurate sources to determine the temperatures of such stars?

[Fafers_br]

No objections. I see you are propposing the temperatures from E. Mamajek's table. I think it's a good source.

[Joey P.]

I think a reasonable rule-of-thumb for star temperatures is that M-type stars usually have temperatures between 3,000 to 4,000 Kelvin or Celsius, type K are between 4,000 to 5,000, and G-type 5,000 to 6,000 (remember there is a relatively small difference between Celsius (subtract 273 from) and Kelvin).

[fyr02]

Joey P.
Although this is somewhat correct - but we are looking for the specific temperatures for each spectral type (M0, M1, M2, M3, etc.)

[Joey P.]

fyr02 wrote:
Joey P.
Although this is somewhat correct - but we are looking for the specific temperatures for each spectral type (M0, M1, M2, M3, etc.)

There's a rough guide here (also including carbon stars, of course):
https://en.wikipedia.org/wiki/Carbon_star#Morgan–Keenan_C_system

[SevenSpheres]

Joey P., this is a better and more complete source, which is why I used it for this pull request.

[Joey P.]

Oh yes, that's right. But what about metallicity ("metals" = everything that is not hydrogen or helium)?

[Sirius_Alpha]

Oh yes, that's right. But what about metallicity

Most stars do not have readily accessible metallicities (as far as I know), certainly not in a systematized way like the data products from Hipparcos or Gaia. If there is a useful [M/H]-T_{eff}-Spectral table out there somewhere, it isn't clear how easily this could be implemented in Celestia's default distribution.