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Title: The age and mass of the α Herculis triple-star system from a mesa grid of rotating stars with 1.3 ≤ M/M {sub ☉} ≤ 8.0

α{sup 1} Her is the second closest asymptotic giant branch (AGB) star to the Sun, and the variable luminous M5 Ib-II member of a triple-stellar system containing G8 III and A9 IV-V components. However, the mass of this important star was previously uncertain, with published values ranging from ∼2-15 M {sub ☉}. As shown by this study, its fortuitous membership in a nearby resolved triple-star system makes it possible to determine its fundamental properties including its mass and age. We present over 20 years of VRI photometry of α{sup 1} Her as well as Wing intermediate-band near-IR TiO and NIR continuum photometry. We introduce a new photometry-based calibration technique and extract the effective temperature and luminosity of α{sup 1} Her, in agreement with recent interferometric measures. We find average values of T {sub eff} = 3280 ± 87 K and log (L/L {sub ☉}) = 3.92 ± 0.14. With the MESA code, we calculate a dense grid of evolutionary tracks for Galactic low- to intermediate-mass (1.3 to 8 M {sub ☉}) rotating stars from the pre-main sequence phase to the advanced AGB phase. We include atomic diffusion and rotation mechanisms to treat the effects of extra elemental mixing. Based onmore » the observed properties of the α Herculis stars, we constrain the age of the system to lie in the range 0.41 to 1.25 Gyr. Thus, the mass of α{sup 1} Her lies in the range 2.175 ≤ M/M {sub ☉} ≤ 3.250. We compare our model-based age inference with recent tracks of the Geneva and STAREVOL codes, and show their agreement. In the prescribed mass range for α{sup 1} Her, the observed {sup 12}C/{sup 13}C and {sup 16}O/{sup 17}O ratios are consistent (within 2σ) with the ratios predicted by the MESA, Geneva, and STAREVOL codes.« less
Authors:
;  [1] ; ;  [2]
  1. School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of)
  2. Department of Astronomy, Villanova University, 800 Lancaster Avenue, Villanova, PA (United States)
Publication Date:
OSTI Identifier:
22340073
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astronomical Journal (New York, N.Y. Online); Journal Volume: 146; Journal Issue: 6; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ASYMPTOTIC SOLUTIONS; CALIBRATION; CARBON 12; CARBON 13; COMPARATIVE EVALUATIONS; DATA; DIFFUSION; ISOTOPE RATIO; LUMINOSITY; MASS; MIXING; NEAR INFRARED RADIATION; OXYGEN 16; OXYGEN 17; PHOTOMETRY; ROTATION; STAR EVOLUTION; SUN; TITANIUM OXIDES