The first year of SN 2004dj in NGC 2403

New BVRI photometry and optical spectroscopy of the Type IIp supernova 2004dj in NGC 2403, obtained during the first year since discovery, are presented. The progenitor cluster, Sandage 96, is also detected on pre-explosion frames. The light curve indicates that the explosion occured about 30 days before discovery, and the plateau phase lasted about +110 \pm 20 days after that. The plateau-phase spectra have been modelled with the SYNOW spectral synthesis code using H, NaI, TiII, ScII, FeII and BaII lines. The SN distance is inferred from the Expanding Photosphere Method and the Standard Candle Method applicable for SNe IIp. They resulted in distances that are consistent with each other as well as earlier Cepheid- and Tully-Fisher distances. The average distance, D = 3.47 \pm 0.29 Mpc is proposed for SN 2004dj and NGC 2403. The nickel mass produced by the explosion is estimated as 0.02 \pm 0.01 M_o. The SED of the progenitor cluster is reanalysed by fitting population synthesis models to our observed BVRI data supplemented by U and JKH magnitudes from the literature. The chi^2-minimization revealed a possible "young" solution with cluster age T_{cl} = 8 Myr, and an "old" solution with T_{cl} = 20 - 30 Myr. The "young" solution would imply a progenitor mass M > 20 M_o, which is higher than the previously detected progenitor masses for Type II SNe.Comment: 19 pages, accepted in MNRA

Addressing ambiguities in the evolutionary status of solar-mass stars

Spectroscopic MK classifications have been obtained for a set of stars having abnormal indices on the Stromgren uvby photometric system. Two of these stars, HD 204848 and HD 207687, show extreme carbon anomalies. Moderately high-resolution spectroscopy (0.2 Angstrom) over the wavelength range of 3900 to 8800 Angstrom was compared with synthetic spectra for evolutionary models to give an indication of the true evolutionary status of these stars. The luminosities predicted from the modeling are found to be in agreement with HIPPARCOS observations

A MODEL-ATMOSPHERE ANALYSIS OF AP STAR HD 26385

An abundance analysis using photographic region spectrograms and fully line-blanketed model atmospheres has been performed for the chemically peculiar (CP) star HD 26385. Model parameters were determined from H-gamma-profile and photometric data. Its pattern of abundance shows that HD 26385 is typically Ap Si-star

MULTIWAVELENGTH SPECTROSCOPY OF THE STABLE SHELL STAR HD-193182

HD 193182 is one of the most interesting ''stable shell stars'' and presents stable shell features which seems to be constant over decades. In this research we analyzed optical, ultraviolet and near-infrared spectra of this little-studied shell star. In the meantime we applied model calculations to the measured spectral parameters of HD 193182 in order to present a more complete view of its stellar and envelope characteristics

ON THE FURTHER OBSERVATIONS OF B-E/SHELL STAR-V-923-AQL

V 923 Aql is one of the candidate B-e stars to be a binary star. In this research, optical and near-infrared spectral measurements of V 923 Aql is presented. V 923 Aql presents variable H Balmer line profiles with shell components. H alpha profiles present R/V, E/C and radial velocity variation. Shell parameters of the envelope are calculated