Veränderlicher BD + 51°2742 = 6.1921 Cygni

The Optical Spectroscopic Evolution of V1974 Cygni (nova Cygni 1992)

Received ; accepted – 2 – ABSTRACT Optical observations of nova V1974 Cygni (Cygni 1992), spanning a 4 year period, have been used to study its spectroscopic evolution. The data cover a wavelength range from ∼ 3200 − 8000Å and follows the nebular evolutionary phase of the ejecta. We have modeled the integrated fluxes by means of the photoionization code CLOUDY. The models were run at a fixed ab...

Toward a Unified Light Curve Model for Multi-wavelength Observations of V1974 Cygni (nova Cygni 1992)

We present a unified model for optical, ultraviolet (UV), and X-ray light curves of V1974 Cygni (Nova Cygni 1992). Based on an optically thick wind model of nova outbursts, we have calculated light curves and searched for the best fit model that is consistent with optical, UV, and X-ray observations. Our best fit model is a white dwarf (WD) of mass 1.05 M⊙ with a chemical composition of X = 0.4...

Cygni : a study of its eclipse timings

EM Cygni is a Z Cam-subtype eclipsing dwarf nova. Its orbital period variations were reported in the past but the results were in conflict to each other while other studies allowed the possibility of no period variation. In this study we report accurate new times of minima of this eclipsing binary and update its O−C diagram. We also estimate the mass transfer rate in EM Cygni system and conclud...

On bD-Sets and Associated Separation Axioms

Non-lte Modeling of Nova Cygni 1992

We present a grid of nova models that have an extremely large number of species treated in NLTE, and apply it to the analysis of an extensive time series of ultraviolet spectroscopic data for Nova Cygni 1992. We use ultraviolet colors to derive the time development of the effective temperature of the expanding atmosphere during the fireball phase and the first ten days of the optically thick wi...