Chowdhury, S. ; Joshi, S. ; Engelbrecht, C. A. ; De Cat, P. ; Joshi, Y. C. ; Paul, K. T.

published in Astrophysics and Space Science, 363 issue 12, pp. 260 (1-18) (2018)

Abstract: We present the results of time-series photometric analysis of 15106 A-K type stars observed by the Kepler space mission. We identified 513 new rotational variables and measured their starspot rotation periods as a function of spectral type and discuss the distribution of their amplitudes. We examined the well-established period-color relationship that applies to stars of spectral types F5-K for all of these rotational variables and, interestingly, found that a similar period-color relationship appears to extend to stars of spectral types A7 to early-F too. This result is not consistent with the very foundation of the period-color relationship. We have characterized 350 new non-radial pulsating variables such as A- and F-type candidate δ Scuti, γ Doradus and hybrid stars, which increases the known candidate non-radial pulsators in the Kepler field significantly, by ˜20%. The relationship between two recently constructed observables, Energy and Efficiency, was also studied for the large sample of non-radial pulsators, which shows that the distribution in the logarithm of Energy (log (En)) can be used as a potential tool to distinguish between the non-radial pulsators, to some extent. Through visual inspection of the light curves and their corresponding frequency spectra, we found 23 new candidate red giant solar-like oscillators not previously reported in the literature. The basic physical parameters such as masses, radii and luminosities of these solar-like oscillators were also derived using asteroseismic relations.

Keyword(s): stars: oscillations ; stars: rotation, starspots ; stars: variables: δ Scuti ; stars: variables ; stars: variables: solarlike
DOI: 10.1007/s10509-018-3480-1
Links: link
Funding: BL/11/IN07