An Investigation of Four Chemically Peculiar Stars with Photometric Periods below 12 Hours

Abstract

We present an investigation of three chemically peculiar (CP) stars and one CP star candidate which exhibit photometric periods below 12 hours. New spectroscopic observations have been acquired which confirm the peculiar nature of all objects. HD 77013 and HD 81076 are classical CP1 (Am) stars; HD 67983 is a marginal CP1 (Am: ) star, and HD 98000 is a CP2 (Ap) star. We have procured observations from the ASAS-3 and SuperWASP archives and obtained additional photometry in order to verify the results from the sky survey data. We have derived astrophysical parameters and investigated the positions of our target stars in the MBol versus log Teff diagram, from which information on evolutionary status has been derived. We present period analyses and discuss each object in detail. From the available data, we propose pulsational variability as the underlying mechanism for the variability in HD 67983, HD 77013 and HD 81076, which offer the opportunity to study the interaction of atomic diffusion and pulsation. HD 67983 and HD 77013 exhibit multiperiodic variability in the gamma Doradus frequency realm; HD 81076 is a delta Scuti star. The CP2 star HD 98000 exhibits monoperiodic variability with a frequency of f~2.148 c/d (P~0.466 d), which we interpret as the rotational period. If this assumption is correct, HD 98000 is the alpha2 Canum Venaticorum (ACV) variable with the shortest period hitherto observed and thus a very interesting object that might help to investigate the influence of rotational mixing on chemical peculiarities.

14 pages, 15 figures, accepted for publication in MNRAS

References in corpus (10)

• Gaia Data Release 1. Summary of the astrometric, photometric, and survey properties
• Gaia Data Release 1: Astrometry - one billion positions, two million proper motions and parallaxes
• The first WASP public data release
• Weak magnetic fields in Ap/Bp stars: Evidence for a dipole field lower limit and a tentative interpretation of the magnetic dichotomy
• Evolutionary state of magnetic chemically peculiar stars
• Pulsation versus metallicism in Am stars as revealed by LAMOST and WASP
• Spots on Am stars
• New Photometrically Variable Magnetic Chemically Peculiar Stars in the ASAS-3 Archive
• CCD photometric search for peculiar stars in open clusters. VIII. King 21, NGC 3293, NGC 5999, NGC 6802, NGC 6830, Ruprecht 44, Ruprecht 115, and Ruprecht 120
• Beta Cephei stars in the ASAS-3 data. I. Long-term variations of periods and amplitudes

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