P Cygni: Many Periods or None? (Abstract)

Volume 23 number 2 (1995)

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John R. Percy

University of Toronto, Toronto, Ontario, Canada

Allen Attard

University of Toronto, Toronto, Ontario, Canada

Matthew Szczesny

University of Toronto, Toronto, Ontario, Canada

Abstract

(Abstract only) P Cygni (V~4.8) is a luminous blue variable which is the prototype of mass-losing stars.In the distant past, this star showed large (? V~3) variations in brightness on a time scale ofyears. More recently, it has shown much smaller variations on time scales of weeks. We have analyzed 550 photoelectric observations of P Cyg from the AAVSO and othersources. These cover the interval 1985 to 1993. We used Fourier and autocorrelationtechniqaues to look for strict periods and for characteristic time scales, respectively. Variations seem to occur on time scales of 30 to 50 days (? V~0.10) and 100 to 120 days (?V~0.05). Our results are compared with recent theoretical calculations by A.N. Cox and hiscollaborators (unpublished).* Allen Attard and Matthew Szczesny were participants in the University of Toronto Mentorship Program, whichenables outstanding senior high school students to work on research projects with University faculty.