New white dwarfs in the Hyades --Results from kinematic and photometric studies

Abstract

On the basis of the PPMXL catalogue (Röser, Demleitner & Schilbach, 2010) we searched for white dwarfs that are also member candidates of the Hyades in a region up to 40 pc from the cluster centre. We use the proper motions from PPMXL in the convergent point method to determine probable kinematic members. We cross-match the kinematic candidates with catalogues containing white dwarfs and, finally, check the kinematic with the photometric distances for consistency. We find the 10 classical white dwarfs in the Hyades and determine their individual kinematic distances. Additionally, we identified 17 new probable (former) Hyades white dwarfs, i.e. white dwarfs co-moving with the bulk space motion of the Hyades cluster. At present, none of them can be excluded from membership on the basis of the measured radial velocities. For another 10 objects, the kinematic and the photometric distances are discordant which rates them as probable non-members. Among the probable members, five white dwarfs are in binary systems, three are known, two are new. There is good indication for an empirical magnitude-distance (from centre) relation, such that the dimmer white dwarfs are farther away from the cluster centre than the brighter ones. Our sample is getting incomplete close behind the centre of the cluster. Follow-up observations are encouraged to independently confirm the predicted radial velocities and the distances of the candidates.

10 pages, 4 figures. Astronomy & Astrophysics (accepted)

References in corpus (10)

• The UKIRT Infrared Deep Sky Survey (UKIDSS)
• The PPMXL catalog of positions and proper motions on the ICRS. Combining USNO-B1.0 and 2MASS
• The Second-Generation Guide Star Catalog: Description and Properties
• The Third US Naval Observatory CCD Astrograph Catalog (UCAC3)
• High-resolution UVES/VLT spectra of white dwarfs observed for the ESO SN Ia Progenitor Survey. III. DA white dwarfs
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• The Hyades stream: evaporated cluster or intrusion from the inner disk?
• Shape parameters of Galactic open clusters
• Spot patterns and differential rotation in the eclipsing pre-CV binary,V471 Tau
• WD0433+270: an old Hyades stream member or an Fe-core white dwarf?

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• A study of high proper-motion white dwarfs I. Spectropolarimetry of a cool hydrogen-rich sample
• Simulations of the Hyades
• The Hyades Cluster: Identification of a Planetary System and Escaping White Dwarfs
• A search for white dwarfs in the Galactic plane: the field and the open cluster population
• Spectroscopic and photometric studies of white dwarfs in the Hyades
• Search for giant planets around seven white dwarfs in the Hyades cluster with the Hubble Space Telescope
• The progenitors of magnetic white dwarfs in open clusters