Computation of Star Effective Temperature (T eff) for STK
Effective temperatures are computed using the temperature relation from Sekiguchi and Fukugita1 which is given as:
where the full sample coefficients from Sekiguchi and Fukugita1, and reproduced in the following table, are used.
Parameter fit for effective temperature relation
|
Parameter |
Value |
|
c 0 |
3.939654 |
|
c 1 |
-0.395361 |
|
c 0 |
0.2082113 |
|
c 0 |
-0.0604097 |
|
f 1 |
0.027153 |
|
f 2 |
0.005036 |
|
g 1 |
0.007367 |
|
h 1 |
-0.01069 |
As of the STK 9.2.1 release, metalicity, 
, and surface gravity, 
, are not used in the computation and are set to zero. The value for 
is taken from the catalog currently in use. In the case of the Tycho 2 catalog where 
is not provided directly, 
is computed as2
.
Future versions of the star catalog data files may be generated that utilize available surface gravity and metalicity data.
Validation
The computation of effective temperature in STK is validated using test stars from Sekiguchi and Fukugita1 with surface gravity and metalicity data from the PASTEL catalog3. The PASTEL catalog is a bibliographical compilation of data and therefore contains multiple entries for many stars. In general, values from the most recent reference in the catalog were used for this analysis. Results are shown in the following table. Note that the reference effective temperature given in the following table is from the PASTEL catalog and does not reflect the similarly named quantity from Sekiguchi and Fukugita.
Effective temperature comparisons
Ref - reference temperature taken from PASTEL catalog; STK - temperature computed by STK ignoring the effects of 
and 
; SF – temperature computed using the full expression from Sekiguchi and Fukugita1.
|
HR |
Hip |
HD |
|
|
|
|
|
Err |
|
Err |
|
2491 |
32349 |
48915 |
0.009 |
4.4 |
0.5 |
9880 |
8632 |
-1248 |
9615 |
-265 |
|
6556 |
86032 |
159561 |
0.155 |
3.89 |
-0.16 |
7906 |
7641 |
-265 |
7964 |
-58 |
|
2943 |
37279 |
61421 |
0.432 |
3.96 |
-0.03 |
6506 |
6351 |
-155 |
6500 |
-6 |
|
2990 |
37826 |
62509 |
0.991 |
3.15 |
0.07 |
4824 |
4938 |
114 |
4845 |
21 |
|
5340 |
69673 |
124897 |
1.239 |
1.69 |
-0.52 |
4280 |
4514 |
234 |
4284 |
4 |
|
6705 |
87833 |
164058 |
1.521 |
1.55 |
-0.08 |
3927 |
4050 |
123 |
3904 |
-23 |
|
1457 |
21421 |
29139 |
1.538 |
1.2 |
-0.15 |
3891 |
4021 |
130 |
3886 |
-5 |
References
1 Sekiguchi, M. and Fukugita, M., “A Study of the B-V Color-Temperature Relation”, The Astronomical Journal, No. 120, pp 1072-1084, August 2000.
2 Perryman, M.A.C., ESA, “The Hipparcos and Tycho catalogues. Astrometric and photometric star catalogues derived from the ESA Hipparcos Space Astrometry Mission”, Publisher: Noordwijk, Netherlands: ESA Publications Division, 1997, Series: ESA SP Series vol no: 1200, ISBN: 9290923997
3 Soubiran, C., Le Campion, J.-F., Cayrel de Strobel, G. and Caillo, A., “The PASTEL Catalogue of Stellar Parameters”, Astronomy and Astrophysics, Volume 515, June 2010.