THE BINARY CEPHEID DL CAS AND THE OPEN CLUSTER NGC 129

Authors

• Hugh C. Harris, U.S. Naval Observatory, Flagstaff, Arizona
• Douglas L. Welch, Dominion Astrophysical Observatory, Herzberg Institute of Astrophysics, Victoria, British Columbia, Canada
• Robert P. Kraft, Lick Observatory, University of California, Santa Cruz, California
• Edward G. Schmidt, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

August 1987

Comments

Published in The Astrophysical Journal 94, 403 (1987). Published by the University of Chicago Press; copyright © 1987 American Astronomical Society; reproduced by permission of the AAS. http://www.journals.uchicago.edu/ApJ/front.html

Abstract

The Cepheid DL Cas and the nonvariable supergiant Star A are confirmed as members of NGC 129, and both are found to be spectroscopic binaries with orbital periods of a few years. Periods and orbits are determined for both stars. Star A is apparently rotating; tidal interaction with its companion is discussed and then rejected as the probable cause of the rotation. The membership of other stars and the velocity of the cluster are redetermined.