UBV photometry of RR Lyrae variables in the globular cluster NGC 6121 (M4)

Journal Article · Mon Oct 01 00:00:00 EDT 1979 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/112572· OSTI ID:5786791

Cacciari, C

Photometry in U, B, and V is reported for 11 RR Lyrae variables and 11 horizontal branch stars in the globular cluster NGC 6121 (M4). The variables cover the whole range of periods present. From the present data and Sturch's (1977) observations of 15 ab-type RR Lyraes the reddening E/sub B/-V=0.36 +- 0.02 mag and the metal abundance (Fe/H)=-1.0 +- 0.4 are derived. Detailed comparisons are made with the results of pulsation theory and the following physical quantities for the variables in M4 are derived: Y=0.28 +- 0.05 and M=0.6 +- 0.1 M/sub sun/ assuming that Mv=0.6 +- 0.1 mag.

• Research Organization: Mount Stromlo and Siding Spring Observatories, Research School of Physical Sciences, The Australian National University
• OSTI ID: 5786791
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 84:10; ISSN ANJOA
• 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
ATOMIC IONS
CHARGED PARTICLES
GIANT STARS
INTERSTELLAR GRAINS
INTERSTELLAR SPACE
IONS
IRON IONS
PARTICLES
PHOTOMETRY
RED GIANT STARS
SPACE
STAR CLUSTERS
STARS
VARIABLE STARS