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

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.