UV Cas: Photometry, Polarization, and Spectrum near Maximum Lightстатья
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Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
Аннотация:The UBV observations of UV Cas during 1996-1999 show mostly irregular light variations. The VB light variations on time scales from one day to two weeks have a smaller amplitude than those on longer time scales. The amplitude of the UBV light variations on time scales from 20 to 200 days reaches 0.4, 0.3, and 0.2 mag, respectively. The colors of UV Cas do not correspond to G5 supergiants, but are more similar to the colors of G0 I stars at substantial U-B color excesses. A comparison of the energy distribution for UV Cas, as constructed from the broadband UBVRI observations in 1982, with the energy distribution for G0 supergiants reveals enhanced near-infrared and ultraviolet emission, which can be attributed to unusual chemical composition of the star. The polarization of light from UV Cas in quiescence is mainly interstellar in origin, although the presence of weak intrinsic polarization produced by the gas-dust circumstellar medium cannot be ruled out either. The strength of CI lines in the spectrum of UV Cas confirms that it belongs to R CrB stars, as well as the conclusion of Orlov and Rodriguez that carbon is appreciably overabundant. The atmospheric metal underabundance in UV Cas may be larger than has been thought previously. The line broadening is sigma = 10.7 km/s. The star's effective temperature appears to be higher than 5500 K. The radial velocity of UV Cas measured from metal and carbon lines is -31.17 +/- 0.38 km/s. The NaI D lines have a split profile, with the two absorbing clouds observed toward UV Cas at distances < 1 kpc and 1.5-2.5 kpc from the Sun contributing to its components.