K2 space photometry reveals rotational modulation and stellar pulsations in chemically peculiar A and B stars
Abstract
Context. The physics of magnetic hot stars and how a large-scale magnetic field affects their interior properties is largely unknown. Few studies have combined high-quality observations and modelling of magnetic pulsating stars, known as magneto-asteroseismology, primarily because of the dearth of detected pulsations in stars with a confirmed and well-characterised large-scale magnetic field.
Aims: We aim to characterise observational signatures of rotation and pulsation in chemically peculiar candidate magnetic stars using photometry from the K2 space mission. Thus, we identify the best candidate targets for ground-based, optical spectropolarimetric follow-up observations to confirm the presence of a large-scale magnetic field.
Methods: We employed customised reduction and detrending tools to process the K2 photometry into optimised light curves for a variability analysis. We searched for the periodic photometric signatures of rotational modulation caused by surface abundance inhomogeneities in 56 chemically peculiar A and B stars. Furthermore, we searched for intrinsic variability caused by pulsations (coherent or otherwise) in the amplitude spectra of these stars.
Results: The rotation periods of 38 chemically peculiar stars are determined, 16 of which are the first determination of the rotation period in the literature. We confirm the discovery of high-overtone roAp pulsation modes in
Conclusions: The discovery of pulsations in a non-negligible fraction of chemically peculiar stars make these stars high-priority targets for spectropolarimetric campaigns to confirm the presence of their expected large-scale magnetic field. The ultimate goal is to perform magneto-asteroseismology and probe the interior physics of magnetic pulsating stars.
- Publication:
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Astronomy and Astrophysics
- Pub Date:
- August 2018
- DOI:
- 10.1051/0004-6361/201833037
- arXiv:
- arXiv:1805.01799
- Bibcode:
- 2018A&A...616A..77B
- Keywords:
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- stars: chemically peculiar;
- stars: magnetic field;
- stars: rotation;
- stars: oscillations;
- stars: early-type;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- Accepted for publication in A&