New red giants in NGC 6791 and NGC 6819 using Kepler superstamps

Abstract

Context. Stars that are members of stellar clusters are assumed to be formed at the same time and place from material with the same initial chemical composition. These additional constraints on the ensemble of cluster stars make these stars suitable as benchmarks. Aims. We aimed 1) to identify previously unknown red giants in the open clusters NGC 6791 and NGC 6819, 2) to extract their asteroseismic parameters, and 3) to determine their cluster membership. Methods. We followed a dedicated method based on difference imaging to extract the light curves of potential red giants in NGC 6791 and NGC 6819 from Kepler superstamp data. We extracted the asteroseismic parameters of the stars that showed solar-like oscillations. We performed an asteroseismic membership study to identify which of these stars are likely to be cluster members. Results. We found 149 red giant stars within the Kepler superstamps, 93 of which are likely cluster members. We were able to find 29 red giants that are not primary targets of Kepler, and therefore, their light curves had not been released previously. Five of these previously unknown red giants have a cluster membership probability greater than 95%.

arXiv comment10 pages, 7 figures, to be published in Astronomy & Astrophysics

References in corpus (26)

• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• Kepler Input Catalog: Photometric Calibration and Stellar Classification
• Kepler Asteroseismology Program: Introduction and First Results
• Nominal values for selected solar and planetary quantities: IAU 2015 Resolution B3
• Asteroseismology of old open clusters with Kepler: direct estimate of the integrated RGB mass loss in NGC6791 and NGC6819
• Gaia Early Data Release 3: The Gaia Catalogue of Nearby Stars
• Initial Characteristics of Kepler Long Cadence Data For Detecting Transiting Planets
• Selection, Prioritization, and Characteristics of Kepler Target Stars
• The Second APOKASC Catalog: The Empirical Approach
• Clusters and mirages: cataloguing stellar aggregates in the Milky Way
• Asteroseismology of the open clusters NGC 6791, NGC 6811, and NGC 6819 from nineteen months of Kepler photometry
• Sounding open clusters: asteroseismic constraints from Kepler on the properties of NGC 6791 and NGC 6819
• Determination of stellar radii from asteroseismic Data
• Automated preparation of Kepler time series of planet hosts for asteroseismic analysis
• Solar-like oscillations in red giants observed with Kepler: comparison of global oscillation parameters from different methods
• An asteroseismic membership study of the red giants in three open clusters observed by Kepler: NGC6791, NGC6819, and NGC6811
• K2P${}^2$ $-$ A photometry pipeline for the K2 mission
• WIYN Open Cluster Study. XXIV. Stellar Radial-Velocity Measurements in NGC 6819
• Detection of solar-like oscillations from Kepler photometry of the open cluster NGC 6819
• Asteroseismic inferences on red giants in open clusters NGC 6791, NGC 6819 and NGC 6811 using Kepler
• The PLATO field selection process I. Identification and content of the long-pointing fields
• Kepler red-clump stars in the field and in open clusters: constraints on core mixing
• The Helium Abundance of NGC 6791 from Modeling of Stellar Oscillations
• Coefficients of variation for detecting solar-like oscillations
• CCD UBV photometry of the open cluster NGC 6819
• The Kepler IRIS Catalog: Image subtraction light curves for 9,150 stars in and around the open clusters NGC 6791 and NGC 6819

Cited by in corpus (1)

• Hidden oscillations in plain sight: identification of seismically unresolved red-giant asteroseismic binary candidates