Evolution of Cepheids with pulsationally-driven mass loss

Conference · Fri Aug 01 04:00:00 EDT 1986

DOI:https://doi.org/10.1007/3-540-17668-3_167· OSTI ID:7259562

Brunish, W M; Willson, L A

Models have been run of intermediate mass stars (5, 6, 7, and 8 M/sub theta/ with Y = 0.28, Z = 0.02) with pulsationally-driven mass loss occurring in the Cepheid instability strip. The new /sup 12/C(..cap alpha..,..gamma..)/sup 16/O rates of Caughlan were used. The enhanced rate extends the tip of the blue loop, allowing the 5 and 6 M/sub theta/ models to re-enter the Cepheid strip, unlike the models calculated using the old rates (Becker, 1981). An investigation was conducted to see if mass loss during the Cepheid stage could redden the tip of the blue loop sufficiently to place it inside the instability strip, thereby ''trapping'' the star, and allowing it to lose mass for a period of time significantly longer than the normal crossing time. Results show that this mechanism does in fact work for a 7 M/sub theta/ star with mass loss rates as low as approx.5 x 10/sup -7/ M/sub theta/ yr/sup -1/. Observations of P-Cygni profiles in Cepheids indicate that this rate is not unreasonable. This behavior acts to reduce the discrepancy between the evolutionary and pulsation-derived masses for Cepheids. Another consequence is that the rates of period change are decreased, bringing them into better agreement with observed values. 7 refs., 2 tabs.

• Research Organization: Los Alamos National Lab., NM (USA); Iowa State Univ. of Science and Technology, Ames (USA)
• DOE Contract Number: W-7405-ENG-36
• OSTI ID: 7259562
• Report Number(s): LA-UR-86-3407; CONF-8608130-2; ON: DE87001957
• 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
ALPHA REACTIONS
CARBON 12 TARGET
CEPHEIDS
CHARGED-PARTICLE REACTIONS
ELECTROMAGNETIC RADIATION
EVEN-EVEN NUCLEI
GAMMA RADIATION
IONIZING RADIATIONS
ISOTOPES
LIGHT NUCLEI
MASS
NUCLEAR REACTIONS
NUCLEI
OXYGEN 16
OXYGEN ISOTOPES
PULSATING VARIABLE STARS
RADIATIONS
STABLE ISOTOPES
STAR EVOLUTION
STARS
TARGETS
VARIABLE STARS