Search for double-mode RR Lyrae stars in Omega Centauri

Journal Article · Fri Aug 01 04:00:00 EDT 1986 · Astron. J.; (United States)

DOI:https://doi.org/10.1086/114165· OSTI ID:7185820

Nemec, J M; Nemec, A F.L.; Norris, J

Using Martin's (1939) extensive photometry of variable stars in the globular cluster Omega Centauri (NGC 5139 = C1323-472), the brightness variations of 55 RR Lyrae stars have been thoroughly analyzed in a search for multiply periodic stars. Despite the fact that there are at least six short-period ab type Blazhko variables in Omega Cen, in the period interval 0.35 to 0.50 days, there appear to be no doubly periodic RR Lyrae stars of the kind previously found in the globular clusters M3, M15, M68, and IC 4499, and in the Draco dwarf galaxy. One possible reason for the absence of such stars in Omega Cen is that the horizontal-branch stars might be rotating relatively faster than similar stars in systems known to have produced RRd stars. This might also explain the apparent absence of RRd stars in M5 (Nemec and Clement, 1986). Other possibilities are discussed. 61 references.

• Research Organization: California Institute of Technology, Pasadena; International Statistics and Research Corp., Brentwood Bay, Canada; Mount Stromlo and Siding Spring Observatories, Canberra, Australia
• OSTI ID: 7185820
• Journal Information: Astron. J.; (United States), Journal Name: Astron. J.; (United States) Vol. 92; 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
ANGULAR VELOCITY
GALAXIES
MASS
MOTION
ROTATION
SPECTROPHOTOMETRY
STAR CLUSTERS
STAR EVOLUTION
STARS
VARIABLE STARS
VELOCITY