EVOLUTIONARY STATUS OF 85 PEGASI
- Department of Astronomy, Yonsei University, Seoul 120-749 (Korea, Republic of)
- The Astrophysical Research Center for the Structure and Evolution of the Cosmos, Sejong University, Seoul 143-747 (Korea, Republic of)
- Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States)
We have investigated the evolutionary status of the visual binary 85 Peg (HD 224930) using a high-resolution spectroscopic analysis and the astrometric calibration of the stellar parameters. In spite of well-determined stellar parameters from HIPPARCOS astrometry and from spectroscopy, 85 Peg has for a long time revealed peculiar properties when attempts have been made to combine an evolutionary model with observation. There has been a chronic problem of the mass ratio of the two components when comparing 85 Peg's dynamical properties to the photometric magnitude difference. Moreover, 85 Peg has been suspected to have unique characteristics in its chemical composition. In order to determine accurate spectroscopic abundances, we have obtained high-resolution echelle spectra for 85 Peg. From our elemental analysis, we found that 85 Peg is alpha-enhanced with respect to the scaled solar abundance by a factor of 2. We then produced, within the framework of the standard stellar theory, grids of stellar model using the most recent observational results. To avoid many-fold degeneracy among physical quantities, a statistical minimization test was carried out between theoretical model grids. Enforcing consistency between the modeling and statistical constraints, we derived a reliable set of physical parameters and confirmed the trinarity of the system. In the context of asteroseismology, the theoretical frequency spectrum of 85 Peg was calculated. 85 Peg A is expected to have a first order spacing {Delta}{nu} {approx} 165 {mu}Hz at the reference frequency {nu}{sub 0} = 790 {mu}Hz.
- OSTI ID:
- 21372003
- Journal Information:
- Astrophysical Journal, Vol. 703, Issue 1; Other Information: DOI: 10.1088/0004-637X/703/1/362; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
Similar Records
Insights from the APOKASC determination of the evolutionary state of red-giant stars by consolidation of different methods
SPECTROSCOPIC ABUNDANCES AND MEMBERSHIP IN THE WOLF 630 MOVING GROUP