Related papers: Modeling He-rich subdwarfs through the hot-flasher…
We study the evolution of a system composed by a 1.4 \msun neutron star and a normal, solar composition star of 2 \msun in orbit with a period of 1 day. Calculations were performed employing the binary hydro code presented in Benvenuto & De…
Helium-rich subdwarf B (He-sdB) stars represent a small group of low-mass hot stars with luminosities greater than those of conventional subdwarf B stars, and effective temperatures lower than those of subdwarf O stars. By measuring their…
We calculated a grid of evolutionary models for white dwarfs with helium cores (He-WDs) and investigated the occurrence of hydrogen-shell flashes due to unstable hydrogen burning via CNO cycling. Our calculations show that such thermal…
The current models of early star and galaxy formation are based upon the hierarchical growth of dark matter halos, within which the baryons condense into stars after cooling down from a hot diffuse phase. The latter is replenished by infall…
We present an analytical and phenomenological model for metal enrichment in halos based on hierarchical structure formation. This model assumes that astration of normal stellar populations along with SNe II already occurs at very high…
We present the analysis of a high-resolution, high-quality sample of optical spectra for 76 subdwarf B (sdB) stars from the ESO Supernova Ia Progenitor Survey (SPY). Effective temperature, surface gravity, and photospheric helium abundance…
The precipitation of cloud particles in brown dwarf and exoplanet atmospheres establishes an ongoing downward flux of condensable elements. To understand the efficiency of cloud formation, it is therefore crucial to quantify the…
We present a schematic model for the formation of baryonic galactic halos and hot gas in the Local Group and the intergalactic medium. We follow the dynamics, chemical evolution, heat flow and gas flows of a hierarchy of scales, including:…
Using the self-consistent modeling of the conditional stellar mass functions across cosmic time by Yang et al. (2012), we make model predictions for the star formation histories (SFHs) of {\it central} galaxies in halos of different masses.…
The mergers of double helium white dwarfs are believed to form isolated helium-rich hot subdwarfs. Observation shows that the helium-rich hot subdwarfs can be divided into two subgroups based on whether the surface is carbon-rich or…
We present a direct comparison between the observed star formation rate functions (SFRF) and the state-of-the-art predictions of semi-analytic models (SAM) of galaxy formation and evolution. We use the PACS Evolutionary Probe Survey (PEP)…
Recent high-resolution simulations of the formation of dark-matter halos have shown that the distribution of subhalos is scale-free, in the sense that if scaled by the velocity dispersion of the parent halo, the velocity distribution…
We present here a detailed pulsational study applied to low-mass He-core white dwarfs, based on full evolutionary models representative of these objects. The background stellar models on which our pulsational analysis was carried out were…
Hot DQ white dwarfs constitute a new class of white dwarf stars, uncovered recently within the framework of the SDSS project. Recently, three hot DQ white dwarfs have been reported to exhibit photometric variability with periods compatible…
We present a stochastic model based on the Monte Carlo technique to study the inhomogeneous chemical evolution of the Galactic halo. In particular, we consider the local enrichment and subsequent mixing of the interstellar gas resulting…
Masses are a fundamental parameter, but they are not well known for most hot subdwarfs. In general, the mass of a hot subdwarf is derived with asteroseismology or dynamical methods, for which it is often difficult to obtain the necessary…
We present preliminary results of 3-D hydro simulations of the interstellar medium evolution in dwarf spheroidal galaxies undergoing star formation for the first time. The star formation is assumed to occur in a sequence of instantaneus…
Hot, compact, hydrogen-deficient pre-white dwarfs (pre-WDs) with effective temperatures of Teff > 70,000 K and a surface gravity of 5.0 < log g < 7.0 are rather rare objects despite recent and ongoing surveys. It is believed that they are…
We compare the metallicity distribution of Galactic Halo stars with 3D realizations of hierarchical galaxy formation. Outflows from dwarf galaxies enrich the intergalactic medium inhomogeneously, at a rate depending on the local galaxy…
We present a general phenomenological model for the metallicity distribution (MD) in terms of [Fe/H] for dwarf spheroidal galaxies (dSphs). These galaxies appear to have stopped accreting gas from the intergalactic medium and are fossilized…