AAS 203rd Meeting, January 2004
Session 8 Delta Scuti and Mira Variables
Poster, Monday, January 5, 2004, 9:20am-6:30pm, Grand Hall

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[8.07] MWC349 is Now a Low-Amplitude Optical Variable

H. Gerhardt (Towson University and Maria Mitchell Observatory), V. Strelnitski (Maria Mitchell Observatory)

MWC349, the only known high-gain natural hydrogen maser and the only known natural laser, has been recognized as an optical variable since 1978 (Gottlieb & Liller). Since the highly variable maser radiation from this star is believed to be pumped by the UV radiation of the star, the star's optical variability is of paramount interest. So far, the type and the amplitude of the variations have been a matter of controversy. Gottlieb and Liller (1978) maintained irregular, large amplitude ( 1.0 magnitude) variations from their blue photographic photometry. Jorgenson et al (2000) suspected a 9-year periodicity with an amplitude of 0.7 magnitude, using red photographic photometry; when combined with photoelectric photometry of Bergner et al (1995), the probable amplitude was lower: 0.5 magnitude. Our BVRI, CCD monitoring of the star from 1997 to 2003, with the typical errors of only 0.01 magnitude in R and I, presents evidence that the amplitude of variations is considerably smaller than earlier studies suggest: it did not surpass 0.15 magnitude in any color, during these 7-years. With the photometric points of the last two years, our 7-year light curve seems to be compatible with the 9-year period suspected by Jorgenson et al (2000), although the amplitude of the variations is considerably (2-3 times) smaller. The implications of the revealed low amplitude optical variations for the observed large variations of hydrogen masers in this source will be discussed. This project was supported by the NSF/REU grant AST-0097694 and the Nantucket Maria Mitchell Association.

The author(s) of this abstract have provided an email address for comments about the abstract: hgerha1@towson.edu

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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.