Hubble Space Telescope spectroscopy of the Balmer lines in Sirius B

摘要: Sirius B is the nearest and brightest of all white dwarfs, but it very difficult to observe at visible wavelengths due overwhelming scattered light contribution from A. However, space we can take advantage superb spatial resolution Hubble Space Telescope (HST) resolve A components. Since closest approach in 1993, separation between two stars has become increasingly favourable have recently been able obtain a spectrum complete Balmer line series for using HST Imaging Spectrograph (STIS). The quality STIS spectra greatly exceeds that previous ground-based spectra, be used provide an important determination stellar temperature (T eff = 25 193 K) gravity (log g 8.556), In addition, obtained new, more accurate, gravitational redshift 80.42 ± 4.83 km s -1 B. Combining these results with photometric data Hipparcos parallax, new determinations mass comparison theoretical mass-radius relation. there are some disparities independently log which may arise flux losses narrow 50 x 0.2 arcsec 2 slit. our measurements Ten Wood evolutionary relation, best estimate dwarf 0.978 M ○. . Within overall uncertainties, this agreement 1.02 by matching