STRONTIUM LINES IN LATE-TYPE SPECTRA

Abstract

Lines of strontium, particularly K 4077 and A 4215 of SVn, are well known in stellar spectra, where they have been extensively used in estimates of absolute magnitude for types F-M. The purpose of this note is to describe the behavior of neighboring lines that may affect the appearance and apparent intensity of each of the three chief strontium lines in late-type spectra. Most of the spectrograms examined, including those traced for Figures 1 and 2, had dispersion 10 A/mm. Sri 1 4607.33.The ultimate line of Sri, X4607, occurs with gradually increasing intensity from type F through the remainder of the stellar sequence of decreasing temperature. In late-type stars it is considerably stronger in dwarfs than in giants. Near-by lines that may affect the Sr i line are listed in Table I. See Figure 1. The V i line 1 4606. 15 is a transition from the ground level and thus, like the Sr i line, strengthens with decreasing temperature ; it is the stronger of the two lines throughout much of the giant sequence. In spectra of S-type stars and in those of late-type dwarfs, however, the Sr i line is dominant.