相关论文: Are the Bulge C-stars in the Sagittarius dwarf Gal…
Carbon abundances in first-ascent giant stars are usually lower than those of their main-sequence counterparts. At moderate metallicities, stellar evolution of single stars cannot account for the existence of red-giant branch stars with…
The characteristics of the stellar populations in the Galactic Bulge inform and constrain the Milky Way's formation and evolution. The metal-poor population is particularly important in light of cosmological simulations, which predict that…
We have identified a new class of Asymptotic Giant Branch (AGB) stars in the Small and Large Magellanic Clouds (SMC/LMC) using optical to infrared photometry, light curves, and optical spectroscopy. The strong dust production and…
[ABRIDGED] In order to trace the origin and evolution of carbon in the Galactic disk we have determined carbon abundances in 51 nearby F and G dwarf stars. The sample is divided into two kinematically distinct subsamples with 35 and 16…
We present ground-based 3 micron spectra of obscured Asymptotic Giant Branch (AGB) stars in the Magellanic Clouds (MCs). We identify the carbon stars on the basis of the 3.1 micron absorption by HCN and C2H2 molecules. We show evidence for…
The first results of a study of the the dwarf spheroidal galaxy, Leo I, using the new Japanese-South African Infrared Survey Facility (IRSF) are presented. J,H,K_{s} observations show that most, if not all, of at least the top one magnitude…
We find that the combined LF of N- and SC-type stars are consistent with a Gaussian distribution peaking at M_bol~ -5.2 mag. The resulting LF however shows two tails at lower and higher luminosities more extended than those previously…
The distance, star formation history and global properties of the Local Group dIrr galaxy SagDIG are derived based on an [I-(V-I)] colour--magnitude diagram of ~1550 stars. A distance of 1.06+/-0.10 Mpc is obtained from the I magnitude of…
The origin of carbon in the Universe remains uncertain. At solar metallicity, binary-stripped massive stars -- stars that lost their envelope through stable interaction with a companion -- have been suggested to produce twice as much carbon…
Galactic globular clusters (GCs) are known to host multiple stellar populations: a first generation with a chemical pattern typical of halo field stars and a second generation (SG) enriched in Na and Al and depleted in O and Mg. Both…
We investigate the frequency of occurrence of Galactic carbon stars as a function of progenitor mass using Gaia data. Small number statistics limit fidelity, but C star frequency agrees with that observed in the Magellanic Clouds (MCs) down…
The possibility that the Sagittarius dwarf spheroidal might have formed as a Searle-Zinn fragment in the outer halo of the Galaxy is discussed. Arguments in favor of this hypothesis are: (1) The luminosity distribution of globular clusters…
We present Spitzer IRS spectra of four carbon stars located in the Galactic Halo and the thick disc. The spectra display typical features of carbon stars with SiC dust emission and C$_2$H$_2$ molecular absorption. Dust radiative transfer…
We study the asymptotic giant branch (AGB) evolution of stars with masses between $1~M_{\odot} - 8.5~M_{\odot}$. We focus on stars with a solar chemical composition, which allows us to interpret evolved stars in the Galaxy. We present a…
We aim to constrain the chemo-dynamical properties of the Sagittarius (Sgr) dwarf galaxy using carbon abundances. Our sample from the \textit{Pristine} Inner Galaxy Survey (PIGS) includes $\sim 350$ metal-poor ([Fe/H]~$<-1.5$) stars in the…
We compare the populations of Red Giant stars and Planetary Nebulae in the Galactic Bulge, in the light of recent determinations of their abundances patterns. We find both populations to be compatible. From the planetary nebulae, we find…
We outline the results of a study of the chemical composition of 14 stars in the Sagittarius dwarf spheroidal galaxy (Sgr dSph). For the Sgr dSph stars with [Fe/H]>-1 the abundances are highly unusual, showing a striking enhancement in…
Abundances of Li, heavy elements and carbon isotope ratios have been measured in 12 J-type galactic carbon stars. The abundance analysis shows that in these stars the abundances of s-process elements with respect to the metallicity are…
An analysis of the fluorine abundance in Galactic AGB carbon stars (24 N-type, 5 SC-type and 5 J-type) is presented. This study uses the state- of-the-art carbon rich atmosphere models and improved atomic and molecular line lists in the 2.3…
We identify the rich Carbon star population of the Magellanic-type dwarf irregular galaxy WLM (Wolf-Lundmark-Melotte) and study its photometric properties from deep near-IR observations. The galaxy exhibits also a clear presence of Oxygen…