The Be Star Newsletter, Volume 39 - October 2008
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Omega CMa outburstSebastián A. Otero
The Southern Be star omega CMa has been brightening in the visual over the past two weeks suggesting a new long-term outburst is ongoing. Analysis of the photometric behaviour of the star shows that it has two kind of outbursts: small outbursts with an amplitude of less than 0.15 mag. that may last 2-3 weeks and huge events separated by 8-9 years. The space between the current outburst and the previous major event seems to be a little shorter than earlier such intervals (7.5 years). The steady brightening of the star, which is more than 0.3 mag. above the quiescent state from last season, indicates that this is not a "mini-outburst" and that another long term cycle is starting. The star entered solar conjunction at V= 4.2 at mid-June, 2008 and was recovered in the morning sky rising from V= 4.0 to 3.8 between October 5 and 19, 2008. By October 22, it was stable at 3.8. Since the early stage of the active phase has not been studied in detail, spectra and observations at all wavelengths are strongly encouraged. The figure shows omega CMa's visual behaviour between January 2005 and the present.
All obervations are visual and made with the unaided eye. The uncertainties are in the range 0.05-0.1 mag. as determined from several works in the past. See Otero et al. (2000) and Moon et al. (2007) and references therein for results and a description of the method. References
Moon, T., Otero, S., Kiss, L., 2007, Combining Visual and Photoelectric
Observations of Semiregular Red Variables, eJAAVSO, 71
Otero, S., Fraser, B., Lloyd, C., 2001, IBVS, 5026
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