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Evolutionary Model and Oscillation Frequencies for alpha Ursae Majoris: A Comparison with Observations
The Astrophysical Journal
|January 21, 2000
Summary
Stellar models indicate alpha Ursae Majoris A is a red giant with a mass of 4.0-4.5 solar masses. Its observed oscillations are likely low-order radial p-modes, consistent with theoretical predictions.
Area of Science:
- * Astrophysics
- * Stellar Astrophysics
- * Asteroseismology
Background:
- * Low-amplitude oscillations of alpha Ursae Majoris A observed by Buzasi et al. using the WIRE satellite.
- * Red giants are crucial for understanding stellar evolution and internal structure.
Purpose of the Study:
- * To derive physically consistent interior models for alpha Ursae Majoris A.
- * To interpret the observed low-amplitude oscillations in the context of stellar models.
Main Methods:
- * Construction of a grid of stellar evolutionary tracks.
- * Calculation of pulsation properties for stellar models.
- * Comparison of model predictions with observational data from WIRE satellite.
Main Results:
- * Models with masses between 4.0-4.5 M☉ and normal helium abundance match observations.
- * Oscillations are best explained as low radial order (n=0, 1, 2) radial (l=0) p-mode oscillations.
- * Higher frequencies may correspond to higher radial order p-modes.
- * Nonradial modes (l=1, 2, 3) are densely packed and unlikely to be resolved.
Conclusions:
- * The mass range of 4.0-4.5 M☉ is consistent with both asteroseismic data and astrometric mass function.
- * The observed oscillations of alpha Ursae Majoris A provide strong constraints on its internal structure and evolutionary state.
- * Further observations may resolve higher-order modes and nonradial oscillations.
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