相关论文: Rotating models for evolved low-mass stars
Aims. We present a spectroscopic analysis of a sample of evolved stars in M67 (turn-off, subgiant and giant stars) in order to bring observational constraints to evolutionary models taking into account non-standard transport processes.…
A long standing problem with asymptotic giant branch (AGB) star models has been their inability to produce the low-luminosity carbon stars in the Large and Small Magellanic Clouds. Dredge-up must begin earlier and extend deeper. We find…
Oxygen and carbon-rich AGB stars - and objects directly polluted by them - are excellent laboratories to investigate the nucleosynthesis and mixing processes occurring during the later phases of the of low- and intermediate-mass star…
If a massive star has lost significant mass during its red-supergiant stage, it would return to blue region in the HR diagram and spend a part of the core-He burning stage as a blue supergiant having a luminosity to mass ratio (L/M)…
We study star formation variability, or burstiness, as a method to constrain and compare different galaxy formation models at high redshift using the Azahar simulation suite. The models range from magneto-hydrodynamics with a…
The relation between the event rate of long Gamma-Ray Bursts at low redshift and the star formation rate is still controversial, especially in the low-redshift end. Dong et al. confirmed that the Gamma-Ray Burst rate always exceeds the star…
(abridged) Numerous spectroscopic observations provide compelling evidence for non-canonical processes that modify the surface abundances of low- and intermediate-mass stars beyond the predictions of standard stellar theory. We study the…
We suggest that the vigorous core convection during core helium flash on the tip of the red giant branch (RGB) of low mass stars excites waves that carry energy to the envelope and inflate it for few years to increase the number of extreme…
Galaxy mergers are believed to trigger strong starbursts. This is well assessed by observations in the local Universe. However the efficiency of this mechanism has poorly been tested so far for high redshift, actively star forming,…
(Abridged) We analyse Hubble Space Telescope images of a complete sample of 341 galaxies drawn from both the Canada France and Autofib/Low Dispersion Survey Spectrograph ground-based redshift surveys. We discuss morphological…
Observations show an almost ubiquitous presence of extra mixing in low-mass upper giant branch stars. The most commonly invoked explanation for this is thermohaline mixing. One-dimensional stellar evolution models include various…
Rotational mixing is a very important but uncertain process in the evolution of massive stars. We propose to use close binaries to test its efficiency. Based on rotating single stellar models we predict nitrogen surface enhancements for…
The fundamental properties of low-mass stars are not as well understood as those of their more massive counterparts. The best method for constraining these properties, especially masses and radii, is to study eclipsing binary systems, but…
Popular models for the origin of gamma-ray bursts (GRBs) include short-lived massive stars as the progenitors of the fireballs. Hence the redshift distribution of GRBs should track the cosmic star formation rate of massive stars accurately.…
Observations of mixed modes in evolved low-mass stars enable us to probe the properties of not only the outer envelope of these stars, but also their deep layers. Among the seismic parameters associated with mixed modes, the gravity offset,…
Mergers in the local universe present a unique opportunity for studying the transformations of galaxies in detail. Presented here are recent results, based on multi-wavelength, high-resolution imaging and medium resolution spectroscopy,…
We characterize the mass-dependent evolution in a large sample of more than 8,000 galaxies using spectroscopic redshifts drawn from the DEEP2 Galaxy Redshift Survey in the range 0.4 < z < 1.4 and stellar masses calculated from K-band…
Angular momentum evolution in low-mass stars is determined by initial conditions during star formation, stellar structure evolution, and the behaviour of stellar magnetic fields. Here we show that the empirical picture of angular momentum…
We combine star formation along the `main sequence', quiescence, and clustering and merging to produce an empirical model for the evolution of individual galaxies. Main sequence star formation alone would significantly steepen the stellar…
We present the first evolutionary models of intermediate mass stars up to their thermal pulses which include effects of rotation on the stellar structure as well as rotationally induced mixing of chemical species and angular momentum. We…