Stellar pulsation and the abundance of helium

Journal Article · Sun Jan 15 04:00:00 EST 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/155812· OSTI ID:6502202

Schmidt, E G

It has been suggested that the appearance of nonvariable stars within the Cepheid strip could be explained by a range in the helium abundance of Population I stars. In order to study this possibility, spectra were obtained of the main-sequence B stars in the galactic cluster NGC 129, which contains a nonvariable Cepheid-strip star, and M25, which contains a relatively hot Cepheid. Unfortunately, several of the stars in these clusters turn out to be helium-weak stars. In NGC 129 two stars which appear normal give a normal abundance, while in M25 all of the observed stars have abnormally low abundances. The significance of the low abundance in M25 is not clear. The abundance in NGC 129 is not low enough to support the above suggestion. 4 figures, 2 tables.

• Research Organization: Univ. of Nebraska, Lincoln
• OSTI ID: 6502202
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 219:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
CEPHEIDS
CHEMICAL COMPOSITION
CRYOGENIC FLUIDS
ELEMENTS
FLUIDS
HELIUM
MAIN SEQUENCE STARS
NONMETALS
PULSATING VARIABLE STARS
PULSATIONS
RARE GASES
SPECTRA
STAR CLUSTERS
STARS
VARIABLE STARS
VISIBLE SPECTRA