Asteroseismology of the Open Clusters NGC 6791, NGC 6811, and NGC 6819 from 19 Months of Kepler Photometry

Author(s)

Enrico Corsaro, Dennis Stello, Daniel Huber, Timothy R. Bedding, Alfio Bonanno, Karsten Brogaard, Thomas Kallinger, Othman Benomar, Timothy R. White, Benoit Mosser, Sarbani Basu, William J. Chaplin, Jørgen Christensen-Dalsgaard, Yvonne P. Elsworth, Rafael A. García, Saskia Hekker, Hans Kjeldsen, Savita Mathur, Søren Meibom, Jennifer R. Hall, Khadeejah A. Ibrahim, Todd C. Klaus

Abstract

We studied solar-like oscillations in 115 red giants in the three open

clusters, NGC 6791, NGC 6811, and NGC 6819, based on photometric data

covering more than 19 months with NASA's Kepler space telescope. We

present the asteroseismic diagrams of the asymptotic parameters

δν02, δν01, and epsilon, which

show clear correlation with fundamental stellar parameters such as mass

and radius. When the stellar populations from the clusters are compared,

we see evidence for a difference in mass of the red giant branch stars

and possibly a difference in structure of the red clump stars, from our

measurements of the small separations δν02 and

δν01. Ensemble échelle diagrams and upper

limits to the linewidths of l = 0 modes as a function of Δν of

the clusters NGC 6791 and NGC 6819 are also shown, together with the

correlation between the l = 0 ridge width and the T eff of

the stars. Lastly, we distinguish between red giant branch and red clump

stars through the measurement of the period spacing of mixed dipole

modes in 53 stars among all the three clusters to verify the stellar

classification from the color-magnitude diagram. These seismic results

also allow us to identify a number of special cases, including evolved

blue stragglers and binaries, as well as stars in late He-core burning

phases, which can be potentially interesting targets for detailed

theoretical modeling.

Organisation(s)

Department of Astrophysics

External organisation(s)

Università degli Studi di Catania, INAF-Osservatorio Astrofisico di Catania, The University of Sydney, National Aeronautics & Space Administration (NASA), University of Victoria, Katholieke Universiteit Leuven, Université de recherche Paris Sciences et Lettres, Yale University, University of Birmingham, University of California, Santa Barbara, Aarhus University, Université Paris VII - Paris-Diderot, University of Amsterdam (UvA), National Center for Atmospheric Research (NCAR), Harvard-Smithsonian Center for Astrophysics

Journal

The Astrophysical Journal

Volume

757

Pages

190

ISSN

0004-637X

DOI

https://doi.org/10.1088/0004-637X/757/2/190

Publication date

2012

Peer reviewed

Yes

Austrian Fields of Science 2012

103004 Astrophysics

Keywords

Portal url

https://ucrisportal.univie.ac.at/en/publications/96711df0-c474-43de-81a6-a70967aa3122