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1999AJ....117.2980V - Astron. J., 117, 2980-2997 (1999/June-0)
Near-infrared photometric studies of R Canis Majoris.
VARRICATT W.P. and ASHOK N.M.
Abstract (from CDS):
Five epochs of primary minima and four epochs of secondary minima are obtained in the present study. The increased depth of the secondary minima in the near-IR bands compared with the optical bands enabled us to determine the moments of secondary minima with nearly the same accuracy as those of primary minima. All the secondary minima appear at phase 0.5, and the durations are equal for the primary and the secondary eclipses. The epochs of primary minima follow the nearly sinusoidal O-C curve that has been observed for this star in previous studies. The values of O-C for the secondary minima were in the same range as those of the primary minima observed by us. We conclude that the system is in a circular orbit. Our observed epochs of primary minima support the presence of a third component in the system, as proposed by Radhakrishnan, Sarma, & Abhyankar. The effect of the presence of a third, noneclipsing, light source would be to suppress the observed depths of both the eclipses, whereas in this system we find that the secondary eclipse depth is being enhanced and the primary eclipse depth is being suppressed compared with expectations. So we have not fitted for a third light in our light-curve analysis, leaving the nature of the third body, if present, undetermined from our present light-curve analysis.
The J-band light curve of R CMa fitted well with a bolometric albedo of the secondary star A2=0.5, as expected for a star with a convective atmosphere. But the K-band light curve showed a value of A2=0.84. A2 is also found to be higher in the broadband light curves than in the narrowband light curves at all the optical wavelengths (except in the U and Un bands, in which the secondary minima are very shallow). This result can provide clues about the cause of the high A2 observed in many Algol-type binary light curves. A2 is also found to vary for light curves at the same wavelengths but taken at different epochs, which helps us to conclude that the high value of A2 seen in many light curves need not be of photospheric origin.
Abstract Copyright: ∼
Journal keyword(s): Stars: Binaries: Eclipsing - Infrared Radiation - Stars: Activity - Stars: Individual: Constellation Name: R Canis Majoris
VizieR on-line data: <Available at CDS (J/AJ/117/2980): table12.dat table13.dat>
Simbad objects: 6
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