Calcium abundance of RR Lyrae variables in. omega. Centaurri and M22

Journal Article · Wed Nov 01 04:00:00 EST 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156556· OSTI ID:6209081

Manduca, A; Bell, R A

Freeman and Rodgers observed 25 RR Lyrae variables in ..omega.. Cen and reported a range in calcium abundance from (Ca/H) = -0.4 to -1.6. This result, however, has been difficult to reconcile with other recent studies of the giant branch of ..omega.. Cen. with a model-atmosphere grid covering the physical parameters expected for RR Lyrae variables, Freeman and Rodgers's data were reanalyzed, by use of their basic method of theoretical relations among the equivalent widths of the K, H4b, and H delta lines and (Ca/H) but with an alternative, synthetic-spectrum approach to the calibration of these relations. When interpreted with the present calibration, the data yield a range in calcium abundance from (Ca/H) = -1.0 to -1.9 for the ..omega.. Cen RR Lyrae variables. This calibration applied to the M22 data of Butler et al gives (Ca/H) = -1.25 for M22. 2 figures, 1 table.

• Research Organization: Univ. of Maryland, College Park
• OSTI ID: 6209081
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 225:3; 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
ABUNDANCE
ALKALINE EARTH METALS
CALCIUM
CALIBRATION
CHEMICAL COMPOSITION
CHEMISTRY
COSMOCHEMISTRY
ELEMENTS
METALS
STARS
VARIABLE STARS