Celestia Forums

The format of the stellar class field in the stars.dat file is a 2-byte integer consisting of four groups of four bits.

The meaning of the four groups (3210) is given at http://members.fortunecity.com/guilpain/Stars_uk.htm as:

3 - star class: 0 = normal, 1 = white dwarf, 2 = neutron star, 3 = black hole (although neutron stars and black holes do not appear in the default stars.dat)

2 - spectral class (0=O through BAFGKMRS to N=9, WC=10, WN=11)

1 - subtype (0 through 9)

0 - luminosity class (0=Ia-0 through Ia II III IV V VI=7)

Groups 2, 1 and 0 do not appear to have any use if group 3 is set to zero.

However since that page was put up Celestia now supports more spectral types (L and T for brown dwarfs, and apparently the latest prerelease supports C type carbon stars as well)

Is it possible to specify these spectral types in stars.dat and if so, what numbers are they?

Also does the prerelease support white dwarf subtypes?

The current spectral class coding is as follows:
0 – O
1 – B
2 – A
3 – F
4 – G
5 – K
6 – M
7 – R
8 – S
9 – N
10 – WC
11 – WN
12 – unknown
13 – L
14 – T
15 – C

There's no support for WD classes yet, but that should be coming.

Grant

Thanks