Neutral gas in the vicinity of Herbig AeBe stars: What can we learn from red-shifted sodium absorption lines?
Variable, high-velocity red-shifted absorption components have been observed recently in the Na D lines of some Herbig Ae/Be stars with non-periodic Algol-type minima. The existence of neutral sodium in the environment of relatively hot stars, such as UX Ori (spectral type A3) cannot be easily explained. We present here the preliminary results of calculations aimed at exploring under which physical conditions a sizable amount of neutral sodium can survive in the immediate vicinity of such a star. Spectral lines of circumstellar origin of other elements are also discussed.
KeywordsOptical Depth Resonance Line Crimean Astrophysical Observatory Protoplanetary Disk Planet Formation
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