Extended Aperture Photometry of K2 RR Lyrae stars

• Main Authors: Plachy, Emese, Molnár, László, Bódi, Attila, Skarka, Marek, Szabó, Pál, Szabó, Róbert, Klagyivik, Péter, Sódor, Ádám, Pope, Benjamin J. S
• Format: Journal Article
• Language: English
• Published: 01-09-2019
• Subjects: Physics - Instrumentation and Methods for Astrophysics; Physics - Solar and Stellar Astrophysics
• DOI: 10.48550/arxiv.1909.00446

The \textit{Kepler} space telescope observed thousands of RR Lyrae stars in
the K2 mission. In this paper we present our photometric solutions using
extended apertures in order to conserve the flux of the stars to the highest
possible extent. With this method we are able to avoid most of the problems
that RR Lyrae light curves produced by other pipelines suffer from. For
post-processing we apply the K2SC pipeline to our light curves. We provide the
EAP (Extended Aperture Photometry) of 432 RR Lyrae stars observed in campaigns
3, 4, 5, and 6. We also provide subclass classifications based on Fourier
parameters. We investigated in particular the presence of the Blazhko effect in
the stars, and found it to be 44.7\% among the RRab stars, in agreement with
results from independent samples. We found that the amplitude and phase
modulation in the Blazhko stars may behave rather differently, at least over
the length of a K2 Campaign. We also identified four anomalous Cepheid
candidates in the sample one of which is potentially the first
Blazhko-modulated member of its class.