SPECTROSCOPIC STUDIES OF DB WHITE-DWARFS - IMPROVED STARK PROFILES FOR OPTICAL-TRANSITIONS OF NEUTRAL HELIUM

New Stark profiles for 21 He I lines and their forbidden components ha ve been calculated for electron densities ranging from 10(14) to 6 x 1 0(17) cm(-3), and for temperatures ranging from 10,000 K to 40,000 K. The profiles include quasi-static broadening by ions as well as electr on broadening-the latter treated within the impact approximation near the core, and within the one-perturber approximation in the far wings. The calculated profiles also allow for line dissolution. These new pr ofiles are the cornerstone of a recent reanalysis of the optical spect rum of a large sample of DB white dwarfs. Our calculations provide a v ery good match to the observed profiles of all the lines, provided tha t Stark broadening dominates other broadening mechanisms.