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Massive stars are the key agents of feedback. Consequently, quantitative analysis of massive stars are required to understand how the feedback of these objects shapes/ creates the large scale structures of the ISM. The giant HII region N206…

Solar and Stellar Astrophysics · Physics 2017-12-27 Varsha Ramachandran , R. Hainich , W. -R. Hamann , L. M. Oskinova , T. Shenar , A. A. C. Sander , H. Todt , J. S. Gallagher

Stars which start their lives with spectral types O and early-B are the progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars, and black holes. These massive stars are the primary sources of stellar feedback in…

Solar and Stellar Astrophysics · Physics 2019-05-22 Varsha Ramachandran , W. -R. Hamann , L. M. Oskinova , J. S. Gallagher , R. Hainich , T. Shenar , A. A. C. Sander , H. Todt , L. Fulmer

Aims. We analyze the multiplicity properties of the massive O-type star population. With 360 O-type stars, this is the largest homogeneous sample of massive stars analyzed to date. Methods. We use multi-epoch spectroscopy and variability…

Context: In cold and dense gas prior to the formation of young stellar objects, heavy molecular species (including CO) are accreted onto dust grains. Under these conditions H$_3^+$ and its deuterated isotopologues become more abundant,…

Astrophysics of Galaxies · Physics 2019-01-16 A. Giannetti , S. Bovino , P. Caselli , S. Leurini , D. R. G. Schleicher , B. Koertgen , K. M. Menten , T. Pillai , F. Wyrowski

We discuss the evolution of oxygen, carbon and nitrogen in galaxies of different morphological type by adopting detailed chemical evolution models with different star formation histories (continuous star formation or starbursts). We start…

Astrophysics · Physics 2009-11-07 Cristina Chiappini , Donatella Romano , Francesca Matteucci

Analysis of late O-type stars observed in the Large Magellanic Cloud (LMC) by the VLT-FLAMES Tarantula Survey (VFTS) revealed a discrepancy between the physical properties estimated from model-atmosphere analysis and those expected from…

Astrophysics of Galaxies · Physics 2020-02-05 N. Markova , J. Puls , P. L. Dufton , D. J. Lennon , C. J. Evans , A. de Koter , O. H. Ramirez-Agudelo , H. Sana , J. S. Vink

Chemical composition is an important factor that affects stellar evolution. The element abundance on the stellar surface evolves along the lifetime of the star because of transport processes, including atomic diffusion. However, models of…

Solar and Stellar Astrophysics · Physics 2022-10-05 Nuno Moedas , Morgan Deal , Diego Bossini , Bernardo Campilho

As JWST uncovers increasingly strong evidence that metal-poor, massive stars in early galaxies dominated reionization, observational constraints on the properties of such stars are more relevant than ever before. However, spectra of…

Solar and Stellar Astrophysics · Physics 2025-03-26 Abby Mintz , O. Grace Telford , Evan N. Kirby , John Chisholm , Kristen B. W. McQuinn , Danielle Berg

Reliable predictions of mass-loss rates are important for massive-star evolution computations. We aim to provide predictions for mass-loss rates and wind-momentum rates of O-type stars, carefully studying the behaviour of these winds as…

Solar and Stellar Astrophysics · Physics 2021-04-14 R. Björklund , J. O. Sundqvist , J. Puls , F. Najarro

Aims: We study the evolution of stellar rotation and wind properties for low-mass main-sequence stars. Our aim is to use rotational evolution models to constrain the mass loss rates in stellar winds and to predict how their properties…

Solar and Stellar Astrophysics · Physics 2015-05-21 C. P. Johnstone , M. Güdel , I. Brott , T. Lüftinger

We examine some debated points in current discussions about rotating stars: the shape, the gravity darkening, the critical velocities, the mass loss rates, the hydrodynamical instabilities, the internal mixing and N--enrichments. The study…

Solar and Stellar Astrophysics · Physics 2015-06-22 Andre Maeder , Georges Meynet

We present NLTE abundances of CNO for a sample of four O9 stars in the Galaxy, together with new determinations of their stellar parameters, $T_{\rm eff}$, $\log g$, $\epsilon$(He) and microturbulence. These new analyses take into account…

Astrophysics · Physics 2009-11-07 M. R. Villamariz , A. Herrero , S. R. Becker , K. Butler

Context. The uncertainty in the degree to which radiation-driven winds of hot stars might be affected by small inhomogeneities in the density leads to a corresponding uncertainty in the determination of the atmospheric mass loss rates from…

Solar and Stellar Astrophysics · Physics 2013-07-12 C. B. Kaschinski , A. W. A. Pauldrach , T. L. Hoffmann

At metallicities lower than that of the Small Magellanic Cloud, it remains essentially unexplored how fossil magnetic fields, forming large-scale magnetospheres, could affect the evolution of massive stars, thereby impacting the fundamental…

Solar and Stellar Astrophysics · Physics 2024-07-31 Z. Keszthelyi , J. Puls , G. Chiaki , H. Nagakura , A. ud-Doula , T. Takiwaki , N. Tominaga

Aims. We analyse the effects of a first generation of fast rotating massive stars on the dynamical and chemical properties of globular clusters. Methods. We use stellar models of fast rotating massive stars, losing mass through a slow…

Astrophysics · Physics 2009-11-13 T. Decressin , C. Charbonnel , G. Meynet

Massive stars are crucial building blocks of galaxies and the universe, as production sites of heavy elements and as stirring agents and energy providers through stellar winds and supernovae. The field of magnetic massive stars has seen…

Solar and Stellar Astrophysics · Physics 2015-05-27 Rolf Walder , Doris Folini , Georges Meynet

Context. The recent detection of nitrogen-enhanced, metal-poor galaxies at high redshift by the James Webb Space Telescope has sparked renewed interest in exploring the chemical evolution of carbon, nitrogen, and oxygen (the CNO elements)…

Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation caused by rotation can dramatically affect a star's chemical…

Solar and Stellar Astrophysics · Physics 2015-06-04 Adrian T. Potter , Christopher A. Tout , Ines Brott

We aim to constrain the mixing processes in low-mass stars by investigating the behaviour of the Li surface abundance after the main sequence. We take advantage of the data from the sixth internal data release of Gaia-ESO, idr6, and from…