Examination of the Evidence for the Existence of Pygmy Stars
Abstract
The kinematic, spectroscopic, and photometric data for five blue stars of high proper motion are reviewed These stars have been suggested to be much fainter than conventional white dwarfs and have been called "pygmy stars," or "blue ultradwarfs" by Zwicky New photometry shows that the stars are redder than the estimates made at the time of discovery by Luyten, and because of the sensitivity of the color4uminosity relation for white dwarfs, this redness removes the kinematic anomaly which originally led to the postulation of this new class of stars We believe there is now no observational evidence- photometric, kinematic, or spectroscopic-for the existence of pygmy stars. Although not pygmies, the stars investigated here are nevertheless quite interesting Three of the five are high-velocity white dwarfs with kinematic properties similar to subdwarfs and RR Lyrae variables of extreme Population II. The red dwarf LP101-15, which forms a wide common proper-motion pair with the white dwarf LP101-16, was found to be an eclipsing system whose primary component is an M4 dwarf The period is either 1 d.26796 or 0 d.63398, depending on the existence of a secondary eclipse Our present photometry is incomplete on this point.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 1967
- DOI:
- 10.1086/149215
- Bibcode:
- 1967ApJ...148..911E