Atmospheric Parameters of Stars

"Stars are too hot for me!"

The stellar atmospheric parameters of effective temperature and surface gravity are of fundamental astrophysical importance. They are the prerequisites to any detailed abundance analysis. As well as defining the physical conditions in the stellar atmosphere, these parameters are directly related to the physical properties of the star; mass, radius and luminosity. Model atmospheres are our analytical link between the physical properties and the observables - flux distributions and spectral line profiles. We can obtain effective temperature and surface gravity from suitable observations, assuming of course that the models we use are adequate and appropriate. The values of effective temperature and surface gravity obtained must necessarily be consistent with the actual physical properties. Unfortunately, the physical properties of stars are not generally directly ascertainable, except in the cases of a few very bright stars and certain binary systems. We have to rely on model atmosphere analyses of spectra in order to deduce the atmospheric parameters.

I have investigated the use of Strömgren photometry, spectrophotometry, medium-resolution spectroscopy and the Balmer lines in the determination of effective temperature, surface gravity and chemical composition. It was found that inappropriate selection of metallicity can have a significant effect on our perceived atmospheric parameters.

Conference Reviews on Parameter Determinations

  1. Click here to see the text of review paper I presented at Vienna Workshop on Model Atmospheres and Spectrum Synthesis in July 1995, or click here to download the gzipped postscript version. Also available via ADS
  2. Click here to access the review on Teff and log g determinations I gave at the Trieste Workshop on ATLAS12 and Related Codes.