Publication details

Understanding the rotational variability of K2 targets: HgMn star KIC 250152017 and blue horizontal branch star KIC 249660366?

Authors

KRTIČKA Jiří KAWKA Adela MIKULÁŠEK Zdeněk FOSSATI Luca KRTIČKOVÁ Iva PRVÁK Milan JANÍK Jan SKARKA Marek LIPTAJ Richard

Year of publication 2020
Type Article in Periodical
Magazine / Source ASTRONOMY & ASTROPHYSICS
MU Faculty or unit

Faculty of Science

Citation
Web https://www.aanda.org/articles/aa/abs/2020/07/aa37953-20/aa37953-20.html
Doi http://dx.doi.org/10.1051/0004-6361/202037953
Keywords stars: variables: general; stars: chemically peculiar; stars: horizontal-branch; stars: atmospheres; stars: early-type
Description Context. Ultraprecise space photometry enables us to reveal light variability even in stars that were previously deemed constant. A large group of such stars show variations that may be rotationally modulated. This type of light variability is of special interest because it provides precise estimates of rotational rates.Aims. We aim to understand the origin of the light variability of K2 targets that show signatures of rotational modulation.Methods. We used phase-resolved medium-resolution X-shooter spectroscopy to understand the light variability of the stars KIC 250152017 and KIC 249660366, which are possibly rotationally modulated. We determined the atmospheric parameters at individual phases and tested the presence of the rotational modulation in the spectra.Results. KIC 250152017 is a HgMn star, whose light variability is caused by the inhomogeneous surface distribution of manganese and iron. It is only the second HgMn star whose light variability is well understood. KIC 249660366 is a He-weak, high-velocity horizontal branch star with overabundances of silicon and argon. The light variability of this star is likely caused by a reflection effect in this post-common envelope binary.
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