Triple-mode cepheid masses

Journal Article · Fri Sep 01 04:00:00 EDT 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156409· OSTI ID:6659182

Cox, A N; King, D S; Hodson, S W

Observations of the light variations of AC Andromedae and TU Cassiopeiae are reviewed. The radial fundamental, first overtone, second overtone, and three nonlinear coupling beat pulsation periods of AC And are presented, confirming the Fitch and Sxeidl work. For TU Cas the radial fundamental, first overtone, and several nonlinear coupling beat periods can be found, and a Fourier analysis has confirmed Faulkner's result at 1.25 days; the small amplitude of this third periodicity, however, makes it reality uncertain. Using an inhomogeneous model with helium enrichment (Y=0.48) in the surface convection zones and mixed downward to the 300,000 K level or 5 x 10/sup -4/ of the mass, the three periods give a mass for AC And as 3 M/sub sun/. This is consistent with an evolutionary first crossing of the Cepheid instability strip. TU Cas has periods that indicate a mass of 4 M/sub sun/ using a similar model but normal composition (Y=d0.356,Z=0.044) at the surface and enriched between 80,000 and 150,000 K (2 x 10/sup -4/ of the mass) to Y=0.70. A first or second crossing is possible; but if the enrichment is by a Cepheid wind and downward mixing, there is more time for TU Cas on the second crossing. If the second overtone of TU Cas does not exist, the variable does not need the thin normal helium composition surface layer and is just another double-mode Cepheid with Yapprox.0.5 down to the 200,000 K level.

• Research Organization: Los Alamos Scientific Laboratory, University of California
• OSTI ID: 6659182
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 224:2; 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
CONVECTION
ENERGY TRANSFER
HEAT TRANSFER
MASS
PULSATIONS
STAR EVOLUTION
STARS
VARIABLE STARS