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We present the results of optical wavelength observations of the unusual SMC eclipsing binary system HD 5980 obtained in 1999 and 2004--2005. Radial velocity curves for the erupting LBV/WR object (star A) and its close WR-like companion (star B) are obtained by deblending the variable emission-line profiles of N IV and N V lines under the simplistic assumption that these lines originate primarily in the winds of star A and star B. The derived masses M_A=58--79 Mo and M_B=51--67 Mo, are more consistent with the stars location near the top of the HRD than previous estimates. The presence of a wind-wind interaction region is inferred from the orbital phase-dependent behavior of He I P Cygni absorption components. The emission-line intensities continued with the declining trend previously seen in UV spectra. The behavior of the photospheric absorption lines is consistent with the results of Schweickhardt (2002) who concludes that the third object in the combined spectrum, star C, is also a binary system with P(starC)~96.5 days, e=0.83. The data used in this paper will be made publicly available for further analysis.
BVR photometric and quasi-simultaneous optical spectroscopic observations of the star HD 81032 have been carried out during the years 2000 - 2004. A photometric period of $18.802 pm 0.07$ d has been detected for this star. A large group of spots with
Radial substructure in the form of rings and gaps has been shown to be ubiquitous among protoplanetary discs. This could be the case in exoKuiper belts as well, and evidence for this is emerging. In this paper we present ALMA observations of the debr
We survey our understanding of classical novae: non-terminal, thermonuclear eruptions on the surfaces of white dwarfs in binary systems. The recent and unexpected discovery of GeV gamma-rays from Galactic novae has highlighted the complexity of novae
Transition disks with large dust cavities around young stars are promising targets for studying planet formation. Previous studies have revealed the presence of gas cavities inside the dust cavities hinting at recently formed, giant planets. However,
The emph{semiclassical Wigner treatment} of Brown and Heller [J. Chem. Phys. 75, 186 (1981)] is applied to triatomic direct photodissociations with the aim of accurately predicting final state distributions at relatively low computational cost, and h