Related papers: The Cosmic Evolution of Magnesium Isotopes
Growing evidence suggests that the stellar initial mass function (IMF) varies systematically across galaxies, deviating from the canonical Milky Way form. Such variations would modify the integrated nucleosynthetic yields, and hence the…
We analyze the relations between the relative magnesium abundances in stars and their metallicities, Galactic orbital elements, and ages. The relative magnesium abundances in metal-poor ([Fe/H] < -0.4) thin-disk stars have been found to…
We investigate the integrated properties of massive (>10 Msun), rotating, single-star stellar populations for a variety of initial rotation rates (v/vcrit=0.0, 0.2, 0.4, 0.5, and 0.6). We couple the new MESA Isochrone and Stellar Tracks…
In order to investigate the possible influence of rotation on the efficiency of the first dredge-up we determined atmospheric parameters, masses, and abundances of carbon, nitrogen, and oxygen in a sample of evolved intermediate mass stars.…
Star formation drives changes in the compositions of galaxies, fusing H and He into heavier nuclei. This paper investigates the differences in abundance evolution between metal and non-metal isotopes using recent models of Galactic chemical…
The first stars fundamentally transformed the early Universe through their production of energetic radiation and the first heavy chemical elements. The impact on cosmic evolution sensitively depends on their initial mass function (IMF),…
We present a nucleosynthesis calculation of a 25 solar mass star of solar composition that includes all relevant isotopes up to polonium. In particular, all stable isotopes and necessary nuclear reaction rates are covered. We follow the…
The Interstellar Medium (ISM) comprises gases at different temperatures and densities, including ionized, atomic, molecular species, and dust particles. The neutral ISM is dominated by neutral hydrogen and has ionization fractions up to 8%.…
The evolution of massive stars is still partly unconstrained. Mass, metallicity, mass loss and rotation are the main drivers of stellar evolution. Binarity and magnetic field may also significantly affect the fate of massive stars. Our goal…
The behavior of the relative magnesium abundances in the thin-disk stars versus their orbital radii suggests that the star formation rate in the thin disk decreases with increasing Galactocentric distance, and there was no star formation…
We characterize stellar, gas, and dark matter mass distributions for 17 nearby massive disk galaxies from the PHANGS sample. This allows us to compute the gravitational potential that vertically confines the interstellar gas and determines…
Using classical model atmospheres and an LTE analysis, Mg isotope ratios 24Mg:25Mg:26Mg are measured in 32 Hyades dwarfs covering 4000K < Teff < 5000K. We find no significant trend in any isotope ratio versus Teff and the mean isotope ratio…
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…
We have determined magnesium isotopic ratios (^{25,26}Mg/Mg) in metal-poor (-2.6 [Fe/H] -1.3) halo dwarfs employing high S/N (90-280) high spectral resolution (R = 10^5) Keck HIRES spectra. Unlike previous claims of an important…
Massive and intermediate mass stars play a crucial role in astrophysics. Indeed, massive stars are the main producers of heavy elements, explode in supernovae at the end of their short lifetimes, and may be the progenitors of gamma ray…
We measure the relationship between stellar mass and stellar metallicity, the stellar mass--metallicity relation (MZR), for 1336 star-forming galaxies at $1.6\le z\le3.0$ (<z>=2.2) using rest-frame far-ultraviolet spectra from the…
Motivated by the WMAP results indicating an early epoch of reionization, we consider alternative cosmic star formation models which are capable of reionizing the early intergalactic medium. We develop models which include an early burst of…
Mass loss due to line-driven winds is central to our understanding of the evolution of massive stars. We extend the evolution models introduced in Paper I, where the mass loss recipe is based on the simultaneous calculation of the wind…
Rotation has a number of important effects on the evolution of stars. It decreases the surface gravity, causes enhanced mass loss and leads to surface abundance anomalies of various chemical isotopes. We have adapted the Cambridge stellar…
The stellar initial mass function (IMF) plays a crucial role in determining the number of surviving stars in galaxies, the chemical composition of the interstellar medium, and the distribution of light in galaxies. A key unsolved question…