Ground‐based follow‐up in relation to Kepler asteroseismic investigation

Uytterhoeven, K.; Briquet, Maryline; Bruntt, H.; Cat, P. De; Frandsen, S.; Gutiérrez‐Soto, J.; Kiss, L. L.; Kurtz, D. W.; Marconi, M.; Molenda-Żakowicz, J.; Østensen, R. H.; Randall, S. K.; Southworth, J.; Szabo, Robert M.

doi:10.1002/asna.201011444

Cited by 31 publications

(27 citation statements)

References 30 publications

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“…Also, detailed information on the stellar chemical composition and rotation rate is lacking. Hence, to exploit the Kepler data best, additional ground-based spectroscopic data are required (Uytterhoeven et al 2010a(Uytterhoeven et al , 2010b.…”

Section: Introductionmentioning

confidence: 99%

LAMOST OBSERVATIONS IN THE KEPLER FIELD. I. DATABASE OF LOW-RESOLUTION SPECTRA

Cat

Ren

et al. 2015

ApJS

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136

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The nearly continuous light curves with micromagnitude precision provided by the space mission Kepler are revolutionizing our view of pulsating stars. They have revealed a vast sea of low-amplitude pulsation modes that were undetectable from Earth. The long time base of Kepler light curves allows for the accurate determination of the frequencies and amplitudes of pulsation modes needed for in-depth asteroseismic modeling. However, for an asteroseismic study to be successful, the first estimates of stellar parameters need to be known and they cannot be derived from the Kepler photometry itself. The Kepler Input Catalog provides values for the effective temperature, surface gravity, and metallicity, but not always with sufficient accuracy. Moreover, information on the chemical composition and rotation rate is lacking. We are collecting low-resolution spectra for objects in the Kepler field of view with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST, Xinglong observatory, China). All of the requested fields have now been observed at least once. In this paper, we describe those observations and provide a useful database for the whole astronomical community.

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Section: Introductionmentioning

confidence: 99%

LAMOST OBSERVATIONS IN THE KEPLER FIELD. I. DATABASE OF LOW-RESOLUTION SPECTRA

Cat

Ren

et al. 2015

ApJS

Self Cite

136

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“…Many projects are striving to determine these atmospheric stellar parameters with the necessary accuracy (e.g. Uytterhoeven et al 2010;Molenda-Żakowicz et al 2010), which is an immense task for the large number of relatively faint stars for which we currently have asteroseismic results thanks to the CoRoT (Baglin et al 2006) and Kepler (Borucki et al 2009) satellites. Note that both CoRoT and Kepler consortia provide A&A 530, A100 (2011) large databases with atmospheric stellar parameters of all observed stars, i.e.…”

Section: Introductionmentioning

confidence: 99%

Asteroseismic inferences on red giants in open clusters NGC 6791, NGC 6819, and NGC 6811 usingKepler

Hekker

Basu

Stello

et al. 2011

A&A

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Context. Four open clusters are present in the Kepler field of view and timeseries of nearly a year in length are now available. These timeseries allow us to derive asteroseismic global oscillation parameters of red-giant stars in the three open clusters NGC 6791, NGC 6819 and NGC 6811. From these parameters and effective temperatures, we derive masses, radii and luminosities for the clusters as well as field red giants. Aims. We study the influence of evolution and metallicity on the observed red-giant populations. Methods. The global oscillation parameters are derived using different published methods and the effective temperatures are derived from 2MASS colours. The observational results are compared with BaSTI evolution models. Results. We find that the mass has significant influence on the asteroseismic quantities Δν vs. ν max relation, while the influence of metallicity is negligible, under the assumption that the metallicity does not affect the excitation/damping of the oscillations. The positions of the stars in the H-R diagram depend on both mass and metallicity. Furthermore, the stellar masses derived for the field stars are bracketed by those of the cluster stars. Conclusions. Both the mass and metallicity contribute to the observed difference in locations in the H-R diagram of the old metal-rich cluster NGC 6791 and the middle-aged solar-metallicity cluster NGC 6819. For the young cluster NGC 6811, the explanation of the position of the stars in the H-R diagram challenges the assumption of solar metallicity, and this open cluster might have significantly lower metallicity [Fe/H] in the range −0.3 to −0.7 dex. Also, nearly all the observed field stars seem to be older than NGC 6811 and younger than NGC 6791.

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“…For our faint stars, spectroscopic observations to determine log g and T eff , and in addition the stellar metallicity, to high enough precision to settle this question are very expensive in telescope time, and may not even be possible. A systematic effort is underway to derive more accurate effective temperatures, surface gravities, and element abundances for KASC target stars (Uytterhoeven et al 2010) that will better inform the uncertainties on these quantities for our fainter sample stars.…”

Section: Explanations For 'Constant' Starsmentioning

confidence: 99%

The Occurrence of Non-pulsating Stars in the gamma Doradus/delta Scuti Pulsation Instability Region

Guzik

Bradley

Jackiewicz

et al. 2013

Astronomical Review

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As part of the NASA Kepler Guest Observer program, we requested and obtained longcadence data on about 2700 faint (Kepler magnitude 14-16) stars with effective temperatures and surface gravities that lie near or within the pulsation instability region for main-sequence γ Doradus and δ Scuti pulsating variables. These variables are of spectral type A-F with masses of 1.4 to 2.5 solar masses. The δ Scuti stars pulsate in radial and non-radial acoustic modes, with periods of a few hours (frequencies ∼10 cycles/day), while γ Doradus variables pulsate in nonradial gravity modes with periods 0.3 to 3 days (frequencies ∼1 cycle/day). Here we consider the light curves and Fourier transforms of 633 stars in an unbiased sample observed by Kepler in Quarters 6-13 (June 2010-June 2012). We show the location of these stars in the log surface gravity-effective temperature diagram compared to the instability region limits established from ground-based observations, and taking into account uncertainties and biases in the Kepler Input Catalog T eff values. While hundreds of variables have been discovered in the Kepler data, about 60% of the stars in our sample do not show any frequencies between 0.2 and 24.4 cycles/day with amplitude above 20 parts per million. We find that six of these apparently constant stars lie within the pulsation instability region. We discuss some possible reasons that these stars do not show photometric variability in the Kepler data. We also comment on the 'non-constant' stars, and on 26 variable-star candidates, many of which also do not lie within the expected instability regions.

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Ground‐based follow‐up in relation to Kepler asteroseismic investigation

Cited by 31 publications

References 30 publications

LAMOST OBSERVATIONS IN THE KEPLER FIELD. I. DATABASE OF LOW-RESOLUTION SPECTRA

LAMOST OBSERVATIONS IN THE KEPLER FIELD. I. DATABASE OF LOW-RESOLUTION SPECTRA

Asteroseismic inferences on red giants in open clusters NGC 6791, NGC 6819, and NGC 6811 usingKepler

The Occurrence of Non-pulsating Stars in the gamma Doradus/delta Scuti Pulsation Instability Region

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