New magnetic chemically peculiar stars and candidates in the ATLAS First Catalog of Variable Stars
arXiv:2107.07990 · doi:10.1093/mnras/stab2065
Abstract
The number of known variable stars has increased by several magnitudes over the last decade, and automated classification routines are becoming increasingly important to cope with this development. Here we show that the "upside-down CBH variables", which were proposed as a potentially new class of variable stars by Heinze et al. (2018) in the ATLAS First Catalogue of Variable Stars, are, at least to a high percentage, made up of alpha2 Canum Venaticorum (ACV) variables - that is, photometrically variable magnetic chemically peculiar (CP2/He-peculiar) stars - with distinct double-wave light curves. Using suitable selection criteria, we identified 264 candidate ACV variables in the ATLAS variable star catalogue. 62 of these objects were spectroscopically confirmed with spectra from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (all new discoveries except for nine stars) and classified on the MK system. The other 202 stars are here presented as ACV star candidates that require spectroscopic confirmation. The vast majority of our sample of stars are main-sequence objects. Derived masses range from 1.4M(Sun) to 5M(Sun), with half our sample stars being situated in the range from 2 M(Sun) to 2.4 M(Sun), in good agreement with the spectral classifications. Most stars belong to the thin or thick disk; four objects, however, classify as members of the halo population. With a peak magnitude distribution at around 14th magnitude, the here presented stars are situated at the faint end of the known Galactic mCP star population. Our study highlights the need to consider rare variability classes, like ACV variables, in automated classification routines.
16 pages, accepted by Monthly Notices of the Royal Astronomical Society
References in corpus (11)
- Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
- New Grids of ATLAS9 Model Atmospheres
- Gaia Data Release 1: Catalogue validation
- The Zwicky Transient Facility Catalog of Periodic Variable Stars
- MOBSTER - II. Identification of rotationally variable A stars observed with \emph{TESS} in Sectors 1 to 4
- Magnetic OB[A] Stars with TESS: probing their Evolutionary and Rotational properties (MOBSTER) - I. First-light observations of known magnetic B and A stars
- Theoretical analysis of the atmospheres of CP stars. Effects of the individual abundance patterns
- New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive
- New and improved rotational periods of magnetic CP stars from ASAS-3, KELT and MASCARA data
- The structural evolution of galaxies with both thin and thick discs
- Global properties of the light curves of magnetic, chemically peculiar stars as a testbed for the existence of dipole-like symmetry in surface structures