相关论文: Hot Horizontal Branch Stars: Predictions for Mass …

We present the results of Monte Carlo mass-loss predictions for hot low-mass stars, specifically for Subdwarf B (SdB) stars. It is shown that the mass-loss rates on the Horizontal Branch (HB) computed from radiative line-driven wind models…

Strong mass loss on the red giant branch (RGB) can result in the formation of extreme horizontal branch (EHB) stars. The EHB stars spend most of their He core and shell burning phase at high temperatures and produce copious ultraviolet…

The presence of a substantial number of hot stars in the extremely metal-rich} open cluster NGC6791 has been a mystery. If these hot stars are in their core helium burning phase, they are significantly bluer (hotter) than predicted by…

I review aspects of the evolution of horizontal branch (HB) stars. I start by discussing current topics in the study of HB stellar evolution, including a brief review of the main determinants of the structure of low-mass core helium burning…

I present the results of radiation-driven mass-loss predictions for hot stars of all mass. Mass loss is an important aspect for the evolution of massive stars, the rotational properties of the progenitors of gamma-ray bursts, and is…

Horizontal branch (HB) morphology is a complex multiple-parameter problem. Besides the metallicity, two other leading parameters are the mass loss rate (MLR) and the initial He abundance of the HB progenitors. Using the STAREV stellar…

Extremely hot horizontal branch (HB) stars and their progeny are widely considered to be responsible for the "ultraviolet upturn" (or UVX) phenomenon observed in elliptical galaxies and the bulges of spirals. Yet, the precise evolutionary…

The connection between mass loss on the red giant branch (RGB) and horizontal branch (HB) morphology in globular clusters (GCs) has long been acknowledged but the mechanisms governing mass loss remains poorly understood from a theoretical…

Massive stars lose a large fraction of their mass to radiation-driven winds throughout their entire life. These outflows impact both the life and death of these stars and their surroundings. Theoretical mass-loss rates of hot, massive stars…

Context. Abundance anomalies have been observed in field sdB stars and in nearly all Horizontal Branch (HB) stars of globular clusters with Teff > 11 000K whatever be the cluster metallicity. Aims. The aim is to determine the abundance…

Stars with very large mass loss on the red-giant branch can undergo the helium flash while descending the white-dwarf cooling curve. Under these conditions the flash convection zone will mix the hydrogen envelope with the hot helium-…

The effects of gravitational settling and radiative levitation in the stellar atmospheres and envelopes of subdwarf B (sdB) stars strongly depend on the presence of weak winds. In the paper the existence of weak radiatively driven winds is…

A low mass star usually experiences stratification and abundance anomalies during its evolution. A 0.95 solar mass star with a metallicity Z = 0.004 is followed from the main-sequence to the Horizontal Branch (HB). On the main-sequence the…

We study the distribution of exoplanets around main sequence (MS) stars and apply our results to the binary model for the formation of extreme horizontal branch (EHB; sdO; sdB; hot subdwarfs) stars. By Binary model we refer both to stellar…

The winds of massive stars remove a significant fraction of their mass, strongly impacting their evolution. As a star evolves, the rate at which it loses mass changes. In stellar evolution codes, different mass-loss recipes are employed for…

Extreme helium stars are very rare low-mass supergiants in a late stage of evolution. They are probably contracting to become white dwarfs following a violent phase of evolution which caused them to become hydrogen-deficient giants,…

We discuss the impact of mixing and rotation along the red-giant branch (RGB) on the properties of horizontal-branch (HB) stars with emphasis on two problems: the nature of the unexpected blue HB population in the metal-rich globular…

Observations of the rotation rates of horizontal branch (HB) stars show puzzling systematics. In particular, cooler HB stars often show rapid rotation (with velocities in excess of 10 km/s), while hotter HB stars typically show much smaller…

Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we have obtained deep far-ultraviolet images of the compact elliptical galaxy M32. When combined with earlier near-ultraviolet images of the same field, these…

This series of papers comprises a systematic exploration of the hypothesis that the far ultraviolet radiation from star clusters and elliptical galaxies originates from extremely hot horizontal-branch (HB) stars and their post-HB progeny.…