scholarly journals The Gaia-ESO Survey and Massive Stars

2014 ◽  
Vol 9 (S307) ◽  
pp. 88-89 ◽  
Author(s):  
Ronny Blomme ◽  
Yves Frémat ◽  
Eric Gosset ◽  
Artemio Herrero ◽  
Alex Lobel ◽  
...  
Keyword(s):  
Radial Velocity ◽  
Stellar Evolution ◽  
Massive Star ◽  
Massive Stars ◽  
Number Of Clusters ◽  
Cluster Membership ◽  
Preliminary Results ◽  
Velocity Information

AbstractAs part of the Gaia-ESO Survey (GES), a number of clusters will be observed that were chosen specifically for their massive-star content. We report on the procedures we followed to determine the stellar parameters from the massive-star spectra of this survey. We intercompare the results from the different techniques used by the nodes of our group to determine these parameters and discuss some of the problems encountered. We present preliminary results for NGC 6705, NGC 3293, and Trumpler 14. We study microturbulence in A-type stars, we use the repeat observation to investigate binarity, and we determine cluster membership from the radial velocity information. The large number of massive-star spectra obtained by the Gaia-ESO Survey will allow us to critically test stellar evolution modelling.

scholarly journals Massive Star Modeling and Nucleosynthesis

2021 ◽  
Vol 8 ◽  
Author(s):  
Sylvia Ekström
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Massive Star ◽  
Nuclear Reactions ◽  
Massive Stars ◽  
Reaction Rates ◽  
Star Evolution ◽  
Structural Impact ◽  
Massive Star Evolution ◽  
The Impact

After a brief introduction to stellar modeling, the main lines of massive star evolution are reviewed, with a focus on the nuclear reactions from which the star gets the needed energy to counterbalance its gravity. The different burning phases are described, as well as the structural impact they have on the star. Some general effects on stellar evolution of uncertainties in the reaction rates are presented, with more precise examples taken from the uncertainties of the 12C(α, γ)16O reaction and the sensitivity of the s-process on many rates. The changes in the evolution of massive stars brought by low or zero metallicity are reviewed. The impact of convection, rotation, mass loss, and binarity on massive star evolution is reviewed, with a focus on the effect they have on the global nucleosynthetic products of the stars.

scholarly journals Massive star evolution: feedbacks in low-Z environment

2018 ◽  
Vol 14 (S344) ◽  
pp. 153-160
Author(s):  
Sylvia Ekström ◽  
Georges Meynet ◽  
Cyril Georgy ◽  
José Groh ◽  
Arthur Choplin ◽  
...  
Keyword(s):  
Chemical Evolution ◽  
Stellar Evolution ◽  
Massive Star ◽  
Dwarf Galaxies ◽  
Massive Stars ◽  
Star Evolution ◽  
Massive Star Evolution

AbstractMassive stars are the drivers of the chemical evolution of dwarf galaxies. We review here the basics of massive star evolution and the specificities of stellar evolution in low-Z environment. We discuss nucleosynthetic aspects and what observations could constrain our view on the first generations of stars.

scholarly journals Massive Stars in M31

2016 ◽  
Vol 12 (S329) ◽  
pp. 419-419
Author(s):  
Jamie R. Lomax ◽  
Matthew Peters ◽  
John Wisniewski ◽  
Julianne Dalcanton ◽  
Benjamin Williams ◽  
...  
Keyword(s):  
Emission Line ◽  
Effective Temperature ◽  
Massive Star ◽  
Milky Way ◽  
Massive Stars ◽  
Stellar Populations ◽  
Preliminary Results ◽  
Large Numbers ◽  
Massive Clusters

AbstractMassive stars are intrinsically rare and therefore present a challenge to understand from a statistical perspective, especially within the Milky Way. We recently conducted follow-up observations to the Panchromatic Hubble Andromeda Treasury (PHAT) survey that were designed to detect more than 10,000 emission line stars, including WRs, by targeting regions in M31 previously known to host large numbers of young, massive clusters and very young stellar populations. Because of the existing PHAT data, we are able to derive an effective temperature, bolarimetric luminosity, and extinction for each of our detected stars. We report on preliminary results of the massive star population of our dataset and discuss how our results compare to previous studies of massive stars in M31.

scholarly journals Combined stellar evolution and spectroscopic modeling of massive stars

2015 ◽  
Vol 11 (A29B) ◽  
pp. 455-457
Author(s):  
Jose H. Groh
Keyword(s):  
High Resolution ◽  
Stellar Evolution ◽  
Massive Star ◽  
Massive Stars ◽  
Atmospheric Modeling ◽  
High Resolution Spectrum ◽  
Morphological Appearance ◽  
First Time

AbstractThe morphological appearance of massive stars during their evolution and at the pre-SN stage is very uncertain, both from theoretical and observational perspectives. We recently developed coupled stellar evolution and atmospheric modeling of stars done with the Geneva and CMFGEN codes, for initial masses between 9 and 120 M⊙. We are able to predict the observables such as the high-resolution spectrum and broadband photometry. Here I discuss how the spectrum of a massive star changes across its evolution and before death. Our models allow, for the first time, direct comparison between predictions from stellar evolution models and observations of SN progenitors.

scholarly journals The Final Fate of Massive Stars

1986 ◽  
Vol 116 ◽  
pp. 423-424
Author(s):  
H. Schild
Keyword(s):  
Stellar Evolution ◽  
Supernova Remnants ◽  
Massive Stars ◽  
Cluster Membership ◽  
Late Stages

The cluster membership of Wolf-Rayet stars, supernova remnants and pulsars is used to study the late stages of stellar evolution of massive stars.

scholarly journals Black Holes and Core Expansion in Massive Star Clusters

2007 ◽  
Vol 3 (S246) ◽  
pp. 176-180
Author(s):  
A. D. Mackey ◽  
M. I. Wilkinson ◽  
M. B. Davies ◽  
G. F. Gilmore
Keyword(s):  
Black Holes ◽  
Stellar Evolution ◽  
Massive Star ◽  
Massive Stars ◽  
Star Clusters ◽  
Magellanic Clouds ◽  
Core Radius ◽  
Stellar Component ◽  
Rapid Mass ◽  
Dynamical Origin

AbstractMassive star clusters in the Magellanic Clouds are observed to follow a striking trend in size with age – older clusters exhibit a much greater spread in core radius than do younger clusters, which are generally compact. We present results from realistic N-body modelling of massive star clusters, aimed at investigating a dynamical origin for the radius-age trend. We find that stellar-mass black holes, formed as remnants of the most massive stars in a cluster, can constitute a dynamically important population. If retained, these objects rapidly form a dense core where interactions are common, resulting in the scattering of black holes into the cluster halo, and the ejection of black holes from the cluster. These processes heat the stellar component, resulting in prolonged core expansion of a magnitude matching the observations. Core expansion at early times does not result from the action of black holes, but can be reproduced by the effects of rapid mass-loss due to stellar evolution in a primordially mass segregated cluster.

scholarly journals Bridging the gap: from massive stars to supernovae

2017 ◽  
Vol 375 (2105) ◽  
pp. 20170025 ◽  
Author(s):  
Justyn R. Maund ◽  
Paul A. Crowther ◽  
Hans-Thomas Janka ◽  
Norbert Langer
Keyword(s):  
Stellar Evolution ◽  
Observational Studies ◽  
Massive Star ◽  
Massive Stars ◽  
Scientific Meeting ◽  
The Other ◽  
Star Evolution ◽  
Massive Star Evolution ◽  
The Universe ◽  
Key Questions

Almost since the beginning, massive stars and their resultant supernovae have played a crucial role in the Universe. These objects produce tremendous amounts of energy and new, heavy elements that enrich galaxies, encourage new stars to form and sculpt the shapes of galaxies that we see today. The end of millions of years of massive star evolution and the beginning of hundreds or thousands of years of supernova evolution are separated by a matter of a few seconds, in which some of the most extreme physics found in the Universe causes the explosive and terminal disruption of the star. Key questions remain unanswered in both the studies of how massive stars evolve and the behaviour of supernovae, and it appears the solutions may not lie on just one side of the explosion or the other or in just the domain of the stellar evolution or the supernova astrophysics communities. The need to view massive star evolution and supernovae as continuous phases in a single narrative motivated the Theo Murphy international scientific meeting ‘Bridging the gap: from massive stars to supernovae’ at Chicheley Hall, UK, in June 2016, with the specific purpose of simultaneously addressing the scientific connections between theoretical and observational studies of massive stars and their supernovae, through engaging astronomers from both communities. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals The main-sequences of NGCs 2 88, 3201, 4590, and 6809

1984 ◽  
Vol 105 ◽  
pp. 157-158
Author(s):  
A.J. Penny
Keyword(s):  
Stellar Evolution ◽  
Globular Cluster ◽  
Fair Agreement ◽  
Number Of Clusters ◽  
Gravitational Settling ◽  
Preliminary Results ◽  
Theoretical Investigations ◽  
Magnitude Diagram ◽  
Ccd Observations ◽  
Photographic Photometry

A globular cluster is an admirable object for the study of stellar evolution and theoretical investigations of the isochrones in the colour-magnitude diagram (CMD) have been numerous, with the most recent being that of Vandenberg (1983, Ap. J. Suppl. 51, 29), but there are still uncertainties such as rotation, abundance variations and gravitational settling. The matching observations are in fair agreement. However only a small number of clusters have been observed and the detailed matching is poor. Most of the CMDs are from photoelectrically calibrated photographic photometry which are affected by the variable background found in clusters. Modern detectors suffer less from this problem and are very sensitive. A programme has been underway on a number of clusters using electronographs and CCDs with the SAAO 1.Om telescope and the crowded-field Starlink Aspic software. This paper reports on preliminary results from four of the clusters. The CCD observations were done in collaboration with W.K. Griffiths of Leeds University.

scholarly journals Progress and problems in massive star pulsation theory

2015 ◽  
Vol 11 (A29B) ◽  
pp. 573-580 ◽  
Author(s):  
Hideyuki Saio ◽  
Cyril Georgy ◽  
Georges Meynet
Keyword(s):  
Stellar Evolution ◽  
Massive Star ◽  
Massive Stars ◽  
Velocity Variations ◽  
Cno Abundances ◽  
Better Than

AbstractMassive stars pulsate in various modes; radial and nonradial p-modes, g-modes, and strange modes including oscillatory convective (non-adiabatic g−) modes. Those modes are responsible for the light and velocity variations of β Cephei stars, slowly pulsating B (SPB) stars, and α Cyg variables. The instability mechanisms for these pulsations are discussed. We also discuss the relation between the evolution of massive stars and the excitation of strange modes, which are considered responsible for the pulsation in most of the α Cyg variables. The surface He and CNO abundances of hotter α Cyg variables seem to indicate that the Ledoux criterion of convection is better than the Schwarzschild criterion, although the latter is extensively used in stellar evolution computations.

scholarly journals The Circumstellar Environment of Embedded Massive Stars

2002 ◽  
Vol 12 ◽  
pp. 143-145 ◽  
Author(s):  
Lee G. Mundy ◽  
Friedrich Wyrowski ◽  
Sarah Watt
Keyword(s):  
Massive Star ◽  
Massive Stars ◽  
Low Mass Stars ◽  
Submillimeter Wavelength ◽  
Star Forming ◽  
Star Forming Regions ◽  
Low Mass ◽  
Circumstellar Environments ◽  
Near Future

Millimeter and submillimeter wavelength images of massive star-forming regions are uncovering the natal material distribution and revealing the complexities of their circumstellar environments on size scales from parsecs to 100’s of AU. Progress in these areas has been slower than for low-mass stars because massive stars are more distant, and because they are gregarious siblings with different evolutionary stages that can co-exist even within a core. Nevertheless, observational goals for the near future include the characterization of an early evolutionary sequence for massive stars, determination if the accretion process and formation sequence for massive stars is similar to that of low-mass stars, and understanding of the role of triggering events in massive star formation.

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