Related papers: Mixing in magnetic OB stars
The most recent detections of LIGO/Virgo and NICER have placed strong constraints on neutron stars' properties. In this work, we study neutron stars modeling them as hybrid stars, compact objects with a quark matter core surrounded by…
Massive stars (those larger than 8 solar masses at formation) have radiative envelopes that cannot sustain a dynamo, the mechanism that produces magnetic fields in lower-mass stars. Despite this, approximately 7\% of massive stars have…
We present computations of nucleosynthesis in red giants and asymptotic giant branch stars of Population I experiencing extended mixing. The assumed physical cause for mass transport is the buoyancy of magnetized structures, according to…
We describe the main-sequence evolution of a rotating 9 $M_\odot$ star. Its interior rotation profile is determined by the redistribution of angular momentum through the meridian circulation and through the shear turbulence generated by the…
Some indirect observations, as the high fraction of Be stars at low metallicity, or the necessity for massive stars to be important sources of primary nitrogen, seem to indicate that very metal poor stars were fast rotators. As a…
Context. We report the results from the determination of stellar masses, carbon and oxygen abundances in the atmospheres of 107 stars from the CHEPS program. Our stars are drawn from a population with a significantly super-solar…
Detailed chemical composition of stars is of prime interest for a range of topics in modern stellar astrophysics, such as the chemical evolution of the Galaxy or the formation, composition, and structure of exoplanets. In this work, we…
At very low metallicity, the effects of differential rotation have a more important impact on the evolution of stars than at high metallicity. Rotational mixing leads to the production of great quantities of helium and of primary $^{14}$N…
About 5% of upper main sequence stars are permeated by a strong magnetic field, the origin of which is still matter of debate. With this work we provide observational material to study how magnetic fields change with the evolution of stars…
Being relatively rare, the properties of magnetic O stars are not fully understood. To date fewer than a dozen of these stars have been confirmed, making any inference of their global properties uncertain due to small number statistics. To…
Recent works have identified that rapidly rotating stars are predominantly binaries with separations of a few to a few tenths of au. This is a crucial range of separation that is often inaccessible to searches of binary stars, providing a…
Understanding the evolution of the N/O ratio in the interstellar medium (ISM) of galaxies is essential if we are to complete our picture of the chemical evolution of galaxies at high redshift, since most observational calibrations of O/H…
A quite remarkable aspect of non-interacting O-stars with detected surface magnetic fields is that they all are very slow rotators. This paper uses this unique property to first demonstrate that the projected rotational speeds of massive,…
Magnetic braking causes the spin-down of single stars as they evolve on the main sequence. Models of magnetic braking can also explain the evolution of close binary systems, including cataclysmic variables. The well-known period gap in the…
We present magnesium abundances derived from high resolution spectra using several Mg I and two high excitation Mg II lines for 19 metal-poor stars with [Fe/H] values between -1.1 and +0.2. The main goal is to search for systematic…
Strong, stable, and organised magnetic fields are present at the surfaces of a small fraction of OBA stars. These "fossil fields" exhibit uniform characteristics in stars over a tremendous range of stellar mass, age, temperature, and…
Models of rotating single stars can successfully account for a wide variety of observed stellar phenomena, such as the surface enhancements of N and He. However, recent observations have questioned the idea that rotational mixing is the…
We acquired high resolution spectroscopic and low resolution spectropolarimetric observations to achieve the following goals: a) to improve the orbital parameters to allow a more in-depth discussion on the possibility of mass transfer in…
This is the second paper in a series aiming at the analysis of nitrogen abundances in O-type stars, to enable further constraints on the early evolution of massive stars. We investigate the NIV lambda4058 emission line formation, provide…
The stars of the middle main sequence have relatively quiescent outer layers, and unusual chemical abundance patterns may develop in their atmospheres. The presence of chemical peculiarities reveal the action of such subsurface phenomena as…