Recalibration of Stellar Temperatures and Reddenings
Session 3 -- Instrumentation and Techniques I: Ground Based
Display presentation, Monday, June 12, 1995, 9:20am - 6:30pm

## [3.08] Recalibration of Stellar Temperatures and Reddenings

W.J.Roberts (CAS), E.K.Grebel (AI\,U\,Bonn)

It has long been suspected that the current calibration of stellar T$_{\rm eff}$ with spectral type has systematic errors. We demonstrate that this suspicion was correct. By comparing synthetic photometry against actual photometry in five photometric systems for a library of stars with high resolution abundance determinations we optimize their temperatures and reddenings using a robust downhill simplex method. The five photometric systems chosen are Johnson--Cousins UBV(RI)$_C$, Washington CMT$_1$T$_2$, Str\"{o}mgren, Geneva, and Vilnius UPXYZVS. The results permit a partial recalibration of the temperatures of the 2D space of MK spectral types.

The reddenings derived for the library stars are a secondary result. The formalism used to compute the interstellar reddenings is that of the authors (1995 A\&AS 109, 293).

Crudely, the results can be summarized as hot stars are not so hot, cool stars not so cool.''