Precise distances to red giant stars with seismic data using the near-IR surface-brightness relation

AbstractThe Kepler and CoRoT satellites have determined precise asteroseismic radii for large samples of red giant stars. Combining these data with data from spectroscopic and photometric surveys has led to precise distance determinations using comprehensive Bayesian methods. Here we determine angular diameters and thus distances using the interferometrically calibrated near-IR surface-brightness method finding good agreement with previous results. The method can easily be reversed when accurate Gaia parallaxes for these stars become available to calibrate the asteroseismic scaling relations.

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A seismic scaling relation for stellar age II: the red giant branch

Monthly Notices of the Royal Astronomical Society Letters ◽

10.1093/mnrasl/slz178 ◽

2019 ◽

Vol 492 (1) ◽

pp. L50-L55 ◽

Cited By ~ 3

Author(s):

Earl Patrick Bellinger

Keyword(s):

Scaling Relations ◽

Red Giants ◽

Giant Stars ◽

Stellar Ages ◽

History Of ◽

Red Giant Stars ◽

Red Giant ◽

Computationally Intensive ◽

Age Relations ◽

Grid Based

ABSTRACT Owing to their simplicity and ease of application, seismic scaling relations are widely used to determine the properties of stars exhibiting solar-like oscillations, such as solar twins and red giants. So far, no seismic scaling relations for determining the ages of red giant stars have been developed. Such relations would be desirable for Galactic Archaeology, which uses stellar ages to map the history of the Milky Way. The ages of red giants must instead be estimated with reference to grids of theoretical stellar models, which can be computationally intensive. Here, I present an exhaustive search for scaling age relations involving different combinations of observable quantities. The candidate scaling relations are calibrated and tested using more than 1000 red giant stars whose ages were obtained via grid-based modelling. I report multiple high-quality scaling relations for red giant branch stars, the best of which are shown to be approximately as accurate as grid-based modelling with typical uncertainties of 15 per cent. Additionally, I present new scaling mass and radius relations for red giants as well.

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Metallicity effect on stellar granulation detected from oscillating red giants in open clusters

Astronomy and Astrophysics ◽

10.1051/0004-6361/201731094 ◽

2017 ◽

Vol 605 ◽

pp. A3 ◽

Cited By ~ 23

Author(s):

E. Corsaro ◽

S. Mathur ◽

R. A. García ◽

P. Gaulme ◽

M. Pinsonneault ◽

...

Keyword(s):

Time Scales ◽

Model Comparison ◽

Open Clusters ◽

Stellar Atmospheres ◽

Surface Gravity ◽

Scaling Relations ◽

Red Giants ◽

Giant Stars ◽

Red Giant Stars ◽

Red Giant

Context. The effect of metallicity on the granulation activity in stars, and hence on the convective motions in general, is still poorly understood. Available spectroscopic parameters from the updated APOGEE-Kepler catalog, coupled with high-precision photometric observations from NASA’s Kepler mission spanning more than four years of observation, make oscillating red giant stars in open clusters crucial testbeds. Aims. We aim to determine the role of metallicity on the stellar granulation activity by discriminating its effect from that of different stellar properties such as surface gravity, mass, and temperature. We analyze 60 known red giant stars belonging to the open clusters NGC 6791, NGC 6819, and NGC 6811, spanning a metallicity range from [Fe/H] ≃ − 0.09 to 0.32. The parameters describing the granulation activity of these stars and their frequency of maximum oscillation power, νmax, are studied while taking into account different masses, metallicities, and stellar evolutionary stages. We derive new scaling relations for the granulation activity, re-calibrate existing ones, and identify the best scaling relations from the available set of observations. Methods. We adopted the Bayesian code Diamonds for the analysis of the background signal in the Fourier spectra of the stars. We performed a Bayesian parameter estimation and model comparison to test the different model hypotheses proposed in this work and in the literature. Results. Metallicity causes a statistically significant change in the amplitude of the granulation activity, with a dependency stronger than that induced by both stellar mass and surface gravity. We also find that the metallicity has a significant impact on the corresponding time scales of the phenomenon. The effect of metallicity on the time scale is stronger than that of mass. Conclusions. A higher metallicity increases the amplitude of granulation and meso-granulation signals and slows down their characteristic time scales toward longer periods. The trend in amplitude is in qualitative agreement with predictions from existing 3D hydrodynamical simulations of stellar atmospheres from main sequence to red giant stars. We confirm that the granulation activity is not sensitive to changes in the stellar core and that it only depends on the atmospheric parameters of stars.

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Surface Brightness Scale of Galactic Cepheids

Symposium - International Astronomical Union ◽

10.1017/s0074180900118996 ◽

1999 ◽

Vol 190 ◽

pp. 561-562

Author(s):

G. P. Di Benedetto

Keyword(s):

Surface Brightness ◽

Variable Stars ◽

Giant Stars ◽

Near Ir

An accurate calibration of the surface brightness scaleSVas a function of the near-IR color (V–K) has been recently measured for non-variable Galactic dwarf and giant stars. It can be shown that this correlation can be applied to theSVscale of Galactic Cepheid variable stars, which are of major cosmological interest.

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