Variable stars with the Kepler space telescope

The Kepler space telescope has revolutionised our knowledge about exoplanets and stars and is continuing to do so in the K2 mission. The exquisite photometric precision, together with the long, uninterrupted observations opened up a new way to investigate the structure and evolution of stars. Asteroseismology, the study of stellar oscillations, allowed us to investigate solar-like stars and to peer into the insides of red giants and massive stars. But many discoveries have been made about classical variable stars too, ranging from pulsators like Cepheids and RR Lyraes to eclipsing binary stars and cataclysmic variables, and even supernovae. In this review, which is far from an exhaustive summary of all results obtained with Kepler, we collected some of the most interesting discoveries, and ponder on the role for amateur observers in this golden era of stellar astrophysics.Comment: 12 pages, 6 figures, published in the Journal of the AAVSO: https://www.aavso.org/apps/jaavso/article/3235/, v2: fixed a bad a reference. arXiv admin note: text overlap with arXiv:1108.3083 by other author

Shockwave Behaviour in RR Lyrae Stars

Here we present the detailed analysis of some modulated Kepler and K2 RR Lyrae stars that show peculiar bump progression in respect to the pulsation phase.Comment: 3 pages, 3 figures, to be published in the proceedings of "The RR Lyrae 2017 Conference", Niepolomice, Poland, 17-21 September 201

A modulated RRd star observed by K2

We report the analysis of the double-mode RR Lyrae star EPIC 205209951, the first modulated RRd star observed from space. The amplitude and phase modulation are present in both modes.Comment: 2 pages, 3 figures, proceedings of the Joint TASC2-KASC9-SPACEINN-HELAS8 Conference "Seismology of the Sun and the Distant Stars 2016", to be published in EPJ Wo

Constraining RRc candidates using SDSS colours

The light variations of first-overtone RR Lyrae stars and contact eclipsing binaries can be difficult to distinguish. The Catalina Periodic Variable Star catalog contains several misclassified objects, despite the classification efforts by Drake et al. (2014). They used metallicity and surface gravity derived from spectroscopic data (from the SDSS database) to rule out binaries. Our aim is to further constrain the catalog using SDSS colours to estimate physical parameters for stars that did not have spectroscopic data.Comment: 2 pages, 1 figure, proceedings of the RRL2015 - High-Precision Studies of RR Lyrae Stars conference, to appear in the Communications from the Konkoly Observator