The Absolute Magnitude and Spectrum of the Class S Star 1 Gruis
Open Access
- 1 August 1953
- journal article
- Published by Oxford University Press (OUP) in Monthly Notices of the Royal Astronomical Society
- Vol. 113 (4) , 510-515
- https://doi.org/10.1093/mnras/113.4.510
Abstract
Spectrograms have been obtained of the typical class S star π1 Gruis, and its close, faint companion. The two stars have a common radial velocity. This and other evidence strongly suggests that the stars form a physical system. The companion is a Go V star and from this fact it is deduced that π1 Gruis has an absolute magnitude of between – 1 and 0 (a normal giant luminosity). An investigation of the spectrum of the S-type star shows that the supergiant characteristics indicated by lines of Sr II, Ca I and Ba II are probably illusory. The star is classified as of equivalent spectral type M7 III. This binary system apparently consists of a late-type giant of abnormal chemical composition and a solar-type dwarf of normal composition.Keywords
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