The masses of retired A stars with asteroseismology: Kepler and K2 observations of exoplanet hosts

TY - JOUR

T1 - The masses of retired A stars with asteroseismology:

T2 - Kepler and K2 observations of exoplanet hosts

AU - North, Thomas S. H.

AU - Campante, Tiago L.

AU - Davies, Guy R.

AU - Grunblatt, Samuel K.

AU - Huber, Daniel

AU - Kuszlewicz, James S.

AU - Lund, Mikkel N.

AU - Cooke, Benjamin F.

AU - Chaplin, William J.

AU - Miglio, Andrea

PY - 2017/12/1

Y1 - 2017/12/1

N2 - We investigate the masses of ‘retired A stars’ using asteroseismic detections on seven low-luminosity red-giant and sub-giant stars observed by the NASA Kepler and K2 missions. Our aim is to explore whether masses derived from spectroscopy and isochrone fitting may have been systematically overestimated. Our targets have all previously been subject to long-term radial velocity observations to detect orbiting bodies, and satisfy the criteria used by Johnson et al. to select survey stars which may have had A-type (or early F-type) main-sequence progenitors. The sample actually spans a somewhat wider range in mass, from ≈ 1 M⊙ up to ≈ 1.7 M⊙. Whilst for five of the seven stars the reported discovery mass from spectroscopy exceeds the mass estimated using asteroseismology, there is no strong evidence for a significant, systematic bias across the sample. Moreover, comparisons with other masses from the literature show that the absolute scale of any differences is highly sensitive to the chosen reference literature mass, with the scatter between different literature masses significantly larger than reported error bars. We find that any mass difference can be explained through use of different constraints during the recovery process. We also conclude that underestimated uncertainties on the input parameters can significantly bias the recovered stellar masses, which may have contributed to the controversy on the mass scale for retired A stars.

AB - We investigate the masses of ‘retired A stars’ using asteroseismic detections on seven low-luminosity red-giant and sub-giant stars observed by the NASA Kepler and K2 missions. Our aim is to explore whether masses derived from spectroscopy and isochrone fitting may have been systematically overestimated. Our targets have all previously been subject to long-term radial velocity observations to detect orbiting bodies, and satisfy the criteria used by Johnson et al. to select survey stars which may have had A-type (or early F-type) main-sequence progenitors. The sample actually spans a somewhat wider range in mass, from ≈ 1 M⊙ up to ≈ 1.7 M⊙. Whilst for five of the seven stars the reported discovery mass from spectroscopy exceeds the mass estimated using asteroseismology, there is no strong evidence for a significant, systematic bias across the sample. Moreover, comparisons with other masses from the literature show that the absolute scale of any differences is highly sensitive to the chosen reference literature mass, with the scatter between different literature masses significantly larger than reported error bars. We find that any mass difference can be explained through use of different constraints during the recovery process. We also conclude that underestimated uncertainties on the input parameters can significantly bias the recovered stellar masses, which may have contributed to the controversy on the mass scale for retired A stars.

KW - asteroseismology

KW - techniques: photometric

KW - stars: evolution

KW - stars: fundamental parameters

U2 - 10.1093/mnras/stx2009

DO - 10.1093/mnras/stx2009

M3 - Article

VL - 472

SP - 1866

EP - 1878

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

IS - 2

ER -