We have calculated the evolution of a 0.49 Msolar hydrogen deficient white dwarf up to very low effective temperatures. The final model has been obtained by calculating the evolution of a H-deficient star from the extreme horizontal branch (EHB) up to the white dwarf regime, without going through the asymptotic giant branch (AGB). Progenitor stars

This work explore the formation and evolution of hydrogen-deficient post-AGB white dwarfs. To this end, we compute the complete evolution of an initially 2.7 M sun star from the ZAMS through the thermally pulsing and mass-loss phases to the white dwarf stage. Particular attention is given to the chemical abundance changes during the whole evolution

Here, we discussed our recent results of elemental abundance survey of Galactic disk based on 181 F- and G-type dwarfs (published by Reddy et al. 2003, MNRAS, 340, 304). Using high-resolution and high signal-to-noise spectra we obtained quantitative abundances for 27 elements: C, N, O, Na, Mg, Al, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Sr

Using a high resolution spectrum of the secondary star in the Low Mass X-ray Binary (LMXB) A0620-00 we have derived the stellar parameters and the veiling caused by the accretion disk in a consistent way. We have used a χ 2 minimization procedure to explore a grid of 600000 synthetic spectra computed for a plausible range of both stellar and

We investigate the presence of possible blends in the spectral region of the Li resonance line at 6708Å in solar-type metal-rich stars using high resolution and high S/N spectroscopic observations. Our analysis does not confirm the identification of a weak absorption feature at 6708.025Å with the low excitation Ti I line proposed recently by Reddy

The black hole binary, Cyg X-1, is generally observed in one of two long duration X-ray states: a low flux, hard spectrum state (most common) and a high flux, soft spectrum state (rare). Models predict that the high/ soft state corresponds to a high mass transfer phase in the binary, and since the X-ray source is fueled by accretion from the