Ten-Year BVRI Monitoring of the Unique Hdrogen Maser Star MWC349 (Abstract)

Volume 35 number 2 (2007)

Vladimir Strelnitski

Abstract

(Abstract only) The variable emission-line star MWC349 is the only known source of high-gain hydrogen maser and laser emission, which seems to arise in the ionized “skin” of the flaring neutral circumstellar disk seen almost edge-on. The uniqueness of this object prompts a short, transitory evolutionary state. Up to the end of 1990s, the data on the optical variability of the star were scarce and controversial. We have monitored it in B, V, R and I with the 31-in CCD telescope of Lowell Observatory for the past ten years. Two modes of variability emerge from our data: (1) a secular decline of 0.03–0.05 magnitude per year (depending on the color band) and (2) possible periodic component, with a period of 3 Å ± 0.3 years and an amplitude of 0.1–0.2 magnitude. More frequent observations of masing hydrogen radio lines, carried out with the 12-m ARO radio telescope on Kitt Peak, revealed a general correlation with the optical, but also strong independent variations on shorter time scales. Preliminary interpretation of these results will be presented. More frequent optical observations of MWC349 in optical domain are obviously needed.