Other
Scientific paper
Feb 1981
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1981apj...244..230c&link_type=abstract
Astrophysical Journal, Part 1, vol. 244, Feb. 15, 1981, p. 230-241.
Other
46
Astronomical Photometry, Cepheid Variables, Opacity, Stellar Models, Helium, Hertzsprung-Russell Diagram, Light Curve, Stellar Evolution, Time Response
Scientific paper
Theoretical models of normal type II Cepheids in the period range 1-10 days have been constructed with the use of the new Carson opacities. The various features of the computed light and velocity curves are found to agree in detail with those actually observed. For example, the Hertzsprung progression of the light curves shows up distinctly in the approximate period range 1-3 days. Masses of observed type II Cepheids, deduced both from the phase of the Hertzsprung bump in the light curves and from the theoretical pulsation constants, are consistent with each other, and average, formally, 0.59 ± 0.03 Msun for globular cluster members and 0.54 ± 0.01 Msun for the archetypal field variable BL Herculis. These masses also agree closely with masses determined directly from atmospheric analyses and indirectly from stellar-evolution theory. From the location of the observed blue edge of the instability strip in the H-R diagram, the helium abundance in the pulsating layers is inferred to be 0.25 ≤ Y ≤ 0.50 and from a comparison of the bump masses and the pulsation-constant masses, it is determined to be Y = 0.31 ± 0.08. This amount of helium is in satisfactory agreement with spectroscopic and evolutionary data for these stars.
If the Cox-Stewart opacities are adopted instead of the Carson opacities, the bump masses turn out to be, at least formally, too small compared to the pulsation-constant masses and to the expected evolutionary masses of the helium cores of these stars, for any realistic helium abundance.
Carson Richard T.
Stothers Richard
Vemury S. K.
No associations
LandOfFree
Type II Cepheids - A comparison of theory with observations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Type II Cepheids - A comparison of theory with observations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Type II Cepheids - A comparison of theory with observations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1407343