Observations and a new interpretation for the delta Scuti variable star VZ Cancri

Journal Article · Sat Sep 01 04:00:00 EDT 1984 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/162403· OSTI ID:6151011

Cox, A N; McNamara, B J; Ryan, W

Extensive numbers of new photoelectric data have been collected and analyzed to investigate the modal behavior of VZ Cnc. Its previously observed periods yield a period ratio of 0.80 implying pulsation in the first and second radial overtones. Of the seventeen delta Scuti stars listed by Fitch and Sziedl which have well-determined periods, it is the only star which apparently does not pulsate in the fundamental mode. This peculiarity is investigated from the standpoint of a change with time of the dominant pulsation mode and atmospheric helium settling. The former suggestion is found to be untenable. The latter is found to increase the theoretical ratio of the first overtone/fundamental periods to that observed. It is thus suggested that VZ Cnc pulsates in these lowest order modes and that its atmosphere has been largely depleted of helium. However, if VZ Cnc has a temperatur as large as 7500 K, its position in the instability strip places this star near the transition line between the first and second overtone pulsation modes, beyond the fundamental mode blue edge. In this case the fundamental mode cannot exist, and the 1H and 2H modes are properly identified.

• Research Organization: Theoretical Division, Los Alamos National Laboratory
• OSTI ID: 6151011
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 284:1; 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
ATMOSPHERES
CONVECTION
DATA ANALYSIS
ELEMENTS
ENERGY TRANSFER
FLUIDS
GASES
HEAT TRANSFER
HELIUM
MASS TRANSFER
MATHEMATICAL MODELS
NONMETALS
OSCILLATION MODES
PHOTOMETRY
PULSATIONS
RARE GASES
STAR MODELS
STARS
STELLAR ATMOSPHERES
VARIABLE STARS