Related papers: Carbon-Deficient Red Giants
Stellar models predict that lithium (Li) inside a star is destroyed during the first dredge-up phase, yet 1.2% of red giant stars are Li-rich. We aim to uncover possible origins of this population, by analysing 1155 Li-rich giants (A(Li)…
Several hypervelocity white dwarfs (HVWDs) with space velocities of $\gtrsim 1000\,\mathrm{kms}^{-1}$ have recently been discovered. One possible origin of these stars is the dynamically-driven double-degenerate double-detonation (D6)…
We present deep BVRI CCD photometry of the stars in the dwarf irregular galaxy SagDIG. The color-magnitude diagrams of the measured stars in SagDIG show a blue plume which consists mostly of young stellar populations, and a well-defined red…
We present a detailed analysis of the carbon and nitrogen abundances of two dwarf carbon-enhanced metal-poor (CEMP) stars: SDSS J1349-0229 and SDSS J0912+0216. We also report the oxygen abundance of SDSS J1349-0229. These stars are…
We investigate the behaviour of asymptotic giant branch (AGB) stars between metallicities Z = 10-4 and Z = 10-8 . We determine which stars undergo an episode of flash-driven mixing, where protons are ingested into the intershell convection…
During the late stages of their evolution, Sun-like stars bring the products of nuclear burning to the surface. Most of the carbon in the Universe is believed to originate from stars with masses up to a few solar masses. Although there is a…
Very metal-deficient stars that exhibit enhancements of their carbon abundances are of crucial importance for understanding a number of issues -- the nature of stellar evolution among the first generations of stars, the shape of the Initial…
We present an analysis of a large sample of moderate resolution Keck LRIS spectra of subgiants and stars at the base of the RGB in M15, most within the range 16.5 < V < 19.5 (1.2 < M_V < 4.2), with the goal of deriving C abundances (from…
We provide a grid of PHOENIX spectra of red giant and supergiant stars, that extend through optical and near-IR wavelengths. For the first time, models are also provided with modified surface abundances of C, N and O, as a step towards…
We have investigated the origin of a sub-class of carbon-polluted white dwarfs (DQ) originally identified as the ``hot DQ" white dwarfs. These objects are relatively hot (10 000 < T_eff < 25 000 K), have markedly higher carbon abundance…
AIMS: After the first dredge-up, low-mass Red Giant Branch (RGB) stars experience an extra-mixing episode that strongly affects the chemical abundances on their surface. This mixing occurs at the bump in the luminosity function. In this…
We analyze the effect of a Chaplygin dark fluid (CDF) core on neutron stars (NSs). To address this study, we focus on the relativistic structure of stellar configurations composed by a dark-energy core, described by a Chaplygin-like…
James Webb Space Telescope (JWST) has uncovered a new population of compact objects that show a unique V-shaped spectral energy distribution (SED) in the UV and optical wavelength range. These so-called "little red dots" (LRDs) often…
Standard stellar evolution theory poorly predicts the surface abundances of chemical species in low-mass, red giant branch (RGB) stars. Observations show an enhancement of p-p chain and CNO cycle products in red giant envelopes, which…
Evolutionary models for massive stars, accounting for rotational mixing effects, do not predict any core-processed material at the surface of B dwarfs with low rotational velocities. Contrary to theoretical expectations, 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…
The thin red giant branch (RGB) of the Carina dwarf spheroidal galaxy appears at first sight quite puzzling and seemingly in contrast with the presence of several distinct bursts of star formation. In this Letter, we provide a measurement…
This paper extends our previous study of planet/brown dwarf accretion by giant stars to solar mass stars located on the red giant branch. The model assumes that the planet is dissipated at the bottom of the convective envelope of the giant…
Carbon is one of the most abundant metals in the universe because of its synthesis in the fundamental triple alpha reaction. The knowledge of carbon abundances in different environments is one key ingredient to our understanding of stellar…
Data-driven analysis methods can help to infer physical properties of red giant stars where "gold-standard" asteroseismic data are not available. The study of optical and infrared spectra of red giant stars with data-driven analyses has…