Period Variation of the Cepheid Zeta Geminorum
Abstract
In anticipation of the coming lunar occultations of Gem on 1974 March 4 and 31, we derive a new ephemeris based on 70 years of radial-velocity measurements. The phases at the two occultations are predicted to be 0.96 and 0.65 phases, respectively, after light maximum. The period decreases at a steady rate of per year, which is 4 times the evolutionary rate for a 7 9) Cepheid in the fundamental mode. However, it is also possible that the period decrease is due to a light-time effect in a long-period (>225 years) binary having a low-mass secondary. Subject headings: Cepheids and W Virginis stars - lunar occultation - stars, individual - stellar evolution
- Publication:
-
The Astrophysical Journal
- Pub Date:
- March 1974
- DOI:
- 10.1086/181436
- Bibcode:
- 1974ApJ...188L..75A