相关论文: Constraints on rotational mixing from surface evol…
The complexity of composite spectra of close binary star system makes study of the spectra of their component stars extremely difficult. For this reason there exists very little information on the photospheric chemical composition of stars…
Aims: We test predictions of evolution models on mixing of CNO-cycled products in massive stars from a fundamental perspective. Relative changes within the theoretical C:N:O abundance ratios and the buildup of helium are compared with…
Recently, measurements of abundances in extremely metal poor (EMP) stars have brought new constraints on stellar evolution models. In an attempt to explain the origin of the abundances observed, we computed pre--supernova evolution models,…
We combine simultaneous constraints on stellar evolutionary status from asteroseismology, and on nitrogen abundances derived from large spectroscopic surveys, to follow nitrogen surface abundances all along the evolution of a low-mass star,…
In this paper we study the effects of rotation in low-mass, low-metallicity RGB stars. We present the first evolutionary models taking into account self-consistently the latest prescriptions for the transport of angular momentum by…
We have composed a sample of 68 massive stars in our galaxy whose projected rotational velocity, effective temperature and gravity are available from high-precision spectroscopic measurements. The additional seven observed variables…
Elemental abundances of carbon, nitrogen, oxygen, magnesium, aluminum, and silicon are presented for a sample of twelve rapidly rotating OB star (v sin i > 60 km s^-1) members of the Cep OB2, Cyg OB3 and Cyg OB7 associations. The abundances…
The influence of rotational mixing on the evolution and asteroseismic properties of solar-type stars is studied. Rotational mixing changes the global properties of a solar-type star with a significant increase of the effective temperature…
We present a new set of stellar yields obtained from rotating stellar models at solar metallicity covering the massive star range (9-120 solar masses). The stellar models were calculated with the latest version of the Geneva stellar…
The orbital angular momentum of a close-orbiting giant planet can be sufficiently large that, if transferred to the envelope of the host star during the red giant branch (RGB) evolution, it can spin-up the star's rotation to unusually large…
Carbon-enhanced metal-poor stars with s-process enrichment (CEMP-s) are believed to be the products of mass transfer from an AGB companion, which has long since become a white dwarf. The surface abundances of CEMP-s stars are thus commonly…
Context. We need to understand the spin evolution of massive stars to compute their internal rotationally induced mixing processes, isolate effects of close binary evolution, and predict the rotation rates of white dwarfs, neutron stars and…
When modelling stars with masses larger than 1.2Msun with no observed chemical peculiarity, atomic diffusion is often neglected because, on its own, it causes unrealistic surface abundances compared with those observed. The reality is that…
The treatment of chemical mixing in the radiative envelopes of intermediate-mass stars has hardly been calibrated so far. Recent asteroseismic studies demonstrated that a constant diffusion coefficient in the radiative envelope is not able…
We derive the effective temperatures and gravities of 461 OB stars in 19 young clusters by fitting the H-gamma profile in their spectra. We use synthetic model profiles for rotating stars to develop a method to estimate the polar gravity…
In an attempt of clarifying the connection between the photospheric abundance anomalies and the stellar rotation as well as of exploring the nature of "normal A" stars, the abundances of seven elements (C, O, Si, Ca, Ti, Fe, and Ba) and the…
We describe the latest developments of the Geneva stellar evolution code in order to model the pre-supernova evolution of rotating massive stars. Rotating and non-rotating stellar models at solar metallicity with masses equal to 12, 15, 20,…
The nature of the first massive stars may be inferred by investigating the origin of the extremely metal-poor (EMP) stars, likely formed from the ejecta of one or a few previous massive stars. We investigate the rotational properties of…
Nuclear reactions drive the stellar evolution and contribute to the stellar and galactic chemicals abundances. New determinations of the nuclear reaction rates for key fusion reactions of stellar evolution are now available, paving the way…
While conventional oscillation experiments measure neutrino mixing parameters with high precision, these measurements are strictly confined to sub-TeV scales. At higher energies, renormalization-group effects can cause these parameters to…