High-resolution photospheric soft X-ray spectrum of Sirius B

High-resolution soft X-ray spectra of Sirius B have been obtained with the 500 lines/mm transmission grating spectrometer on Exosat. A large grid of model atmospheres has been used to constrain the effective temperature to the 25,000-26,000-K range. The results also indicate that the gravity of Sirius B is in the log g = 8.5-8.7 range. Although some evidence for the detection of helium in the photosphere exists, a model with no photospheric helium is also consistent with the results. 27 references