Complex Variability of the Peculiar Emission-line Star MWC349 (Abstract)

Volume 29 number 2 (2001)

Regina Jorgenson

Maria Mitchell Observatory 3 Vestal Street Nantucket, MA 02554

Vladimir Strelnitski

Maria Mitchell Observatory 3 Vestal Street Nantucket, MA 02554

Abstract

(Abstract only) We review the results of a multi-wavelength study of the unique variable star MWC349 done at the Maria Mitchell Observatory. This early-type, emission-line star is the only known natural hydrogen maser and the only known natural laser, both originating in the ionized, expanding atmosphere of an edge-on circumstellar disk. We have studied the variability of the star on the red photographic plates of the Harvard College Obsrvatory plate collection (for the years 1967–1982) and monitored it for three years (1997–2000) in UBVRI (with the 31-inch CCD telescope of the Lowell Observatory in Flagstaff) and in the millimeter radio domain (with the 12-m NRAO radio telescope on Kitt Peak). We reveal several types of variability in this star: long time-scale variations with a probable quasi-period of 9.2 years and a relatively large amplitude (± 0.4 magnitude) in the red photographic domain; small-amplitude (± 0.07 magnitude) variations with a quasi-period of 1.5 years in all the observed colors of the optical domain; complex variations, with several different time scales, in the masing hydrogen recombination radio lines; and, probably, slight variations of the radio continuum that correlate with those of the optical light. We discuss possible physical mechanisms responsible for all these variations.