A Theoretical γ Doradus Instability Strip

In this paper, we present the first theoretical γ Doradus instability strip. We find that our model instability strip agrees very well with the previously established, observationally based, instability strip of Handler & Shobbrook. We stress, as do Guzik et al., that the convection zone depth plays the major role in the determination of our instability strip. Once this depth becomes too deep or too shallow, the convection zone no longer allows for pulsational instability. Our theoretical γ Dor instability strip is bounded by ~6850 and 7360 K at the red and blue edge, respectively, on the zero-age main sequence and by ~6560 and 7000 K at the red and blue edge, respectively, approximately 2 mag more luminous. This theoretical strip, transformed to the observer's color-magnitude diagram, overlays the region where most of the 30 bona fide γ Dor stars are found.

[1]  P. Flower,et al.  Transformations from Theoretical Hertzsprung-Russell Diagrams to Color-Magnitude Diagrams: Effective Temperatures, B-V Colors, and Bolometric Corrections , 1996 .

[2]  F. M. Zerbi,et al.  γ Doradus Stars: Defining a New Class of Pulsating Variables , 1999, astro-ph/9905042.

[3]  J. Guzik,et al.  Seismological Comparisons of Solar Models with Element Diffusion Using the MHD, Opal, and Sireff Equations of State , 1997 .

[4]  G. Henry,et al.  10 New γ Doradus and δ Scuti Stars , 2001 .

[5]  Joyce A. Guzik,et al.  Driving the Gravity-Mode Pulsations in γ Doradus Variables , 2000 .

[6]  Michel Casse,et al.  Origin and evolution of the elements , 1993 .

[7]  Forrest J. Rogers,et al.  Updated Opal Opacities , 1996 .

[8]  W. Fowler,et al.  Thermonuclear reaction rates V , 1988 .

[9]  G. Handler,et al.  On the relationship between the δ Scuti and γ Doradus pulsators , 2002, astro-ph/0202152.

[10]  I. Iben.  Stellar evolution. i - the approach to the main sequence. , 1965 .

[11]  E. Quataert,et al.  Tidal Excitation of Modes in Binary Systems with Applications to Binary Pulsars , 1995, astro-ph/9503053.

[12]  M. Breger.  Asteroseismology of Delta Scuti stars , 2000 .

[13]  W. Pesnell.  Nonradial, nonadiabatic stellar pulsations , 1990 .

[14]  M. Templeton,et al.  Asteroseismology of the Multiply Periodic δ Scuti Star θ Tucanae , 2000 .

[15]  C. Aerts,et al.  Tidally induced radial-velocity variations in close binaries , 2002, astro-ph/0201052.

[16]  I. Iben.  Thermal pulses: p-capture, alpha -capture, s-process nucleosynthesis; and convective mixing in a star of intermediate mass. , 1975 .

[17]  K. Krisciunas,et al.  The multiperiodicity of the $\gamma$ Doradus stars HD 224945 and HD 224638 as detected from a multisite campaign , 2002, astro-ph/0201200.

[18]  I. Iben.  A Comparison Between Homogeneous Stellar Models and the Observations. , 1963 .

[19]  J. Guzik,et al.  A Proposed Pulsation Driving Mechanism for γ Doradus Variable Stars , 2002 .

[20]  M. Breger,et al.  delta Scuti and related stars: Analysis of the R00 Catalogue , 2001 .

[21]  E. Böhm-Vitense.  Introduction to Stellar Astrophysics: Volume 3, Stellar Structure and Evolution , 1992 .

[22]  D. James,et al.  Discovery and analysis of p-mode and g-mode oscillations in the A-type primary of the eccentric binary HD 209295 , 2002, astro-ph/0202214.

[23]  D. Kurtz.  The Impact of Large‐Scale Surveys on Pulsating Star Research: IAU Colloquium 176 , 2000 .

[24]  D. Crawford.  Empirical calibration of the ubvy,beta systems. I. The F-type stars. , 1975 .

[25]  I. Iben.  Stellar evolution. III - The evolution of a 5 solar masses star from the main sequence through core helium burning. , 1966 .

[26]  E. Böhm-Vitense.  Introduction to Stellar Astrophysics , 1989 .