The threshold for stellar winds in hot main-sequence stars

摘要: The profiles of ultraviolet resonance lines C IV were surveyed in a sample 29 cluster and association members the spectral type range O9-B2 III-V, together with few field stars interest. temperatures gravities taken from model atmosphere analysis by Grigsby, Morrison, & Anderson (1992), luminosities estimated on basis distances recent literature. A parameter P(sub w) was defined order to describe degree assymetry profile. This parameter, total equivalent width, found be well correlated stellar luminosity temperature. anomalous noted: tau Sco, HD 66665, 13621, ON HD12323 201345. results suggest sudden onset observable mass loss at T(effective) = 27,500 +/- 500 K, log (L/solar luminosity) 4.4 0.12, agreement previous study Prinja (1989). At 28,000 K g 4, our non-LTE atmospheres show an enhancement ground-state population C(+3) their topmost layer, which could responsible for initiation winds via radiation pressure ions, or visibility ions wind because increase optical depth outermost layers.