Related papers: Using M32 to Study Rapid Phases of Stellar Evoluti…
We collected F606W- and F814W-band time-series data of the Sagittarius low-reddening window in the Galactic bulge with the Advanced Camera far Surveys mounted on the Hubble Space Telescope. We sampled the region approximately every two…
We present illustrative models for the UV to millimeter emission of starburst galaxies which are treated as an ensemble of optically thick giant molecular clouds (GMCs) centrally illuminated by recently formed stars. The models follow the…
Low-mass stars are currently the most promising targets for detecting and characterizing habitable planets in the solar neighborhood. However, the ultraviolet (UV) radiation emitted by such stars can erode and modify planetary atmospheres…
Hot subdwarf (SD) stars are the stripped cores of red giant stars in transition to the white dwarf sequence. The B-type subdwarfs (sdB) are powered by helium fusion in the core, more evolved ones (sdO) by shell burning. Low mass SDs may…
Ultra-massive white dwarfs ($\rm M_{WD} \gtrsim 1.05\, M_{\odot}$) are considered powerful tools to study type Ia supernovae explosions, merger events, the occurrence of physical processes in the Super Asymptotic Giant Branch (SAGB) phase,…
The recent discovery of hidden non-axysimmetric and disk-like structures in bright Virgo dwarf elliptical and lenticular galaxies (dE/dSph/dS0) indicates that they may have late-type progenitors. Using N-body simulations we follow the…
The Local Group member M33 is a pure disk galaxy bearing no prominent bulge or stellar halo. It constitutes a challenge for any hierarchical galaxy formation theory and an ideal laboratory for studying quiescent star formation. Using…
Evolved stars dominate galactic spectra, enrich the galactic medium, expand to change their planetary systems, eject winds of a complex nature, produce spectacular nebulae and illuminate them, and transfer material between binary…
We derive absorption indices of ellipticals in clusters at z=0.37 from medium-resolution spectroscopy together with kinematical parameters. These galaxies exhibit a relationship between the Mgb linestrength and their internal velocity…
The time evolution of galaxy cluster abundance is used to constrain cosmological parameters in dark matter models containing a fraction of hot particles (massive neutrino). We test the modified MDM models with cosmic gravitational waves…
Late-type spiral galaxies are thought to be the dynamically simplest type of disk galaxies and our understanding of their properties plays a key role in the galaxy formation and evolution scenarios. The low surface brightness (LSB) galaxy…
White dwarf stars are the most common endpoint of stellar evolution. Therefore, these old, numerous and compact objects provide valuable information on the late stages of stellar evolution, the physics of dense plasma and the structure and…
Their ubiquity and extreme densities make star clusters probes of prime importance of galaxy evolution. Old globular clusters keep imprints of the physical conditions of their assembly in the early Universe, and younger stellar objects,…
The evolution of central stars of planetary nebulae can proceed in several distinct ways, either leading to H-deficiency or to H-normal surface composition. Several new simulations of the evolution channels that lead to H-deficiency are now…
Context. Ultra-diffuse galaxies (UDGs) are an intriguing population of galaxies. Despite their dwarf-like stellar masses and low surface brightness, they have large half-light radii and exhibit a diverse range of globular cluster (GC)…
Galaxy counts from bright ultraviolet (UV) and deep optical spectroscopic surveys have revealed an unexpectedly large number of very blue galaxies. The colors and luminosities of these objects indicate that they are dwarf galaxies…
Recent observations indicate that in some Milky Way globular clusters (GCs) pristine red giant branch (RGB) stars appear more centrally concentrated than enriched ones. This contradicts most multiple stellar population (MSP) formation…
Abridged. White dwarf stars are the final evolutionary stage of the vast majority of stars, including our Sun. The study of white dwarfs has potential applications to different fields of astrophysics. In particular, they can be used as…
For 32 central stars of PNe we present their parameters interpolated among the new evolutionary sequences. The derived stellar final masses are confined between 0.53 and 0.58 $M_\odot$ in good agreement with the peak in the white dwarf mass…
We introduce our project that investigates the kinematic properties of early-type galaxies in 6 distant poor clusters at z~0.25. This study represents a continuation of our efforts to understand galaxy evolution in low-density environments.…