scholarly journals Physics and evolution of the most massive stars in 30 Doradus. Mass loss, envelope inflation, and a variable upper stellar mass limit

2021 ◽  
Author(s):  
G. Gräfener
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Stellar Mass ◽  
Mass Limit ◽  
30 Doradus

scholarly journals Massive star mass-loss revealed by X-ray observations of young supernovae

2018 ◽  
Vol 14 (S346) ◽  
pp. 83-87
Author(s):  
Vikram V. Dwarkadas
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Ambient Medium ◽  
Mass Loss Rate ◽  
Stellar Mass ◽  
X Rays ◽  
X Ray ◽  
The Common ◽  
Almost All ◽  
Loss Rates

AbstractMassive stars lose a considerable amount of mass during their lifetime. When the star explodes as a supernova (SN), the resulting shock wave expands in the medium created by the stellar mass-loss. Thermal X-ray emission from the SN depends on the square of the density of the ambient medium, which in turn depends on the mass-loss rate (and velocity) of the progenitor wind. The emission can therefore be used to probe the stellar mass-loss in the decades or centuries before the star’s death.We have aggregated together data available in the literature, or analysed by us, to compute the X-ray lightcurves of almost all young supernovae detectable in X-rays. We use this database to explore the mass-loss rates of massive stars that collapse to form supernovae. Mass-loss rates are lowest for the common Type IIP supernovae, but increase by several orders of magnitude for the highest luminosity X-ray SNe.

scholarly journals How to form a 200 M⊙ star

1986 ◽  
Vol 116 ◽  
pp. 271-273 ◽  
Author(s):  
Hans Zinnecker
Keyword(s):  
Massive Stars ◽  
Hii Regions ◽  
Stellar Mass ◽  
Mass Limit ◽  
The Core ◽  
Dense Cluster

Stellar coalescence is suggested as a possible mechanism for doubling the upper stellar mass limit from ∼100M⊙ to ∼200M⊙ in a moderately dense cluster of a few hundred young massive stars (∼105 M⊙ pc−3). The merger will be between the two components of the dominant central tight binary formed in the core of the cluster by the N-body evolution. This process may occur in some giant extragalactic HII regions.

scholarly journals Re-examing the Upper Mass Limit of Very Massive Stars: VFTS 682, an isolated ~130 M⊙ twin of R136’s WN5h core stars

2016 ◽  
Vol 12 (S329) ◽  
pp. 131-135
Author(s):  
M. M. Rubio-Díez ◽  
F. Najarro ◽  
M. García ◽  
J. O. Sundqvist
Keyword(s):  
Massive Star ◽  
Spectroscopic Analysis ◽  
Massive Stars ◽  
Stellar Mass ◽  
Photometric Study ◽  
Mass Limit ◽  
Stellar Properties ◽  
Massive Clusters ◽  
K Band

AbstractRecent studies of WNh stars at the cores of young massive clusters have challenged the previously accepted upper stellar mass limit (~150 M⊙), suggesting some of these objects may have initial masses as high as 300 M⊙. We investigated the possible existence of observed stars above ~150 M⊙ by i) examining the nature and stellar properties of VFTS 682, a recently identified WNh5 very massive star, and ii) studying the uncertainties in the luminosity estimates of R136’s core stars due to crowding. Our spectroscopic analysis reveals that the most massive members of R136 and VFTS 682 are very similar and our K-band photometric study of R136’s core stars shows that the measurements seem to display higher uncertainties than previous studies suggested; moreover, for the most massive stars in the cluster, R136a1 and a2, we found previous magnitudes were underestimated by at least 0.4 mag. As such, luminosities and masses of these stars have to be significantly scaled down, which then also lowers the hitherto observed upper mass limit of stars.

scholarly journals Progenitor for Type Ic Supernova 2007bi

2011 ◽  
Vol 7 (S279) ◽  
pp. 427-428
Author(s):  
Takashi Yoshida ◽  
Hideyuki Umeda
Keyword(s):  
Light Curve ◽  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Massive Stars ◽  
Mass Loss Rate ◽  
Mass Range ◽  
Stellar Mass ◽  
Core Collapse ◽  
Core Collapse Supernova

AbstractWe investigate the evolution of very massive stars with Z = 0.2 Z⊙ to constrain the progenitor of the extremely luminous Type Ic SN 2007bi. In order to reproduce the 56Ni amount produced in SN 2007bi, the range of the stellar mass at the zero-age main-sequence is expected to be 515 - 575M⊙ for pair-instability supernova and 110 - 280M⊙ for core-collapse supernova. Uncertainty in the mass loss rate affects the mass range appropriate for the explosion of SN 2007bi. A core-collapse supernova of a WO star evolved from a 110 M⊙ star produces sufficient radioactive 56Ni to reproduce the light curve of SN 2007bi.

scholarly journals Environments of massive stars and the upper mass limit

2011 ◽  
Vol 7 (S279) ◽  
pp. 9-17
Author(s):  
Paul A. Crowther
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
High Redshift ◽  
Star Clusters ◽  
Stellar Mass ◽  
Gamma Ray Bursts ◽  
Core Collapse ◽  
Mass Limit ◽  
Host Galaxies ◽  
Long Duration

AbstractThe locations of massive stars (≥ 8M⊙) within their host galaxies is reviewed. These range from distributed OB associations to dense star clusters within giant Hii regions. A comparison between massive stars and the environments of core-collapse supernovae and long duration Gamma Ray Bursts is made, both at low and high redshift. We also address the question of the upper stellar mass limit, since very massive stars (VMS, Minit ≫ 100M⊙) may produce exceptionally bright core-collapse supernovae or pair instability supernovae.

scholarly journals Candidate protostars in the vicinity of 30 Doradus

1991 ◽  
Vol 148 ◽  
pp. 202-204
Author(s):  
A. R. Hyland ◽  
T. J. Jones
Keyword(s):  
Star Formation ◽  
Mass Loss ◽  
Near Infrared ◽  
Massive Stars ◽  
Spatial Separation ◽  
Central Cluster ◽  
Highly Efficient ◽  
Infrared Survey ◽  
30 Doradus

Four candidate protostars have been identified, with luminosities of 1-5×'l04L⊙ and masses of 10-20M⊙, in a magnitude-limited near-infrared survey of the 30-Dor complex. Each is associated with a dense knot in the nebular arcs. We suggest that both the knots and the associated star formation result from the compression of interacting arcs of mass-loss winds from hot massive stars in the central cluster and other nearby clusters. This mode of star formation appears to be highly efficient. In the 30-Dor region there is a clear spatial separation of the young blue stars and older red stars, strengthening the evidence for a multiple starburst in the region.

scholarly journals Very Massive Stars in the local Universe

2012 ◽  
Vol 10 (H16) ◽  
pp. 51-79 ◽  
Author(s):  
Jorick S. Vink ◽  
Alexander Heger ◽  
Mark R. Krumholz ◽  
Joachim Puls ◽  
S. Banerjee ◽  
...  
Keyword(s):  
Mass Loss ◽  
Paradigm Shift ◽  
Massive Stars ◽  
General Assembly ◽  
Mass Limit ◽  
Physical Processes ◽  
Local Universe ◽  
The Status ◽  
Broad Consensus

AbstractRecent studies have claimed the existence of very massive stars (VMS) up to 300M⊙in the local Universe. As this finding may represent a paradigm shift for the canonical stellar upper-mass limit of 150M⊙, it is timely to discuss the status of the data, as well as the far-reaching implications of such objects. We held a Joint Discussion at the General Assembly in Beijing to discuss (i) the determination of the current masses of the most massive stars, (ii) the formation of VMS, (iii) their mass loss, and (iv) their evolution and final fate. The prime aim was to reach broad consensus between observers and theorists on how to identify and quantify the dominant physical processes.

scholarly journals Very massive stars: a metallicity-dependent upper-mass limit, slow winds, and the self-enrichment of globular clusters

2018 ◽  
Vol 615 ◽  
pp. A119 ◽  
Author(s):  
Jorick S. Vink
Keyword(s):  
Monte Carlo ◽  
Star Formation ◽  
Mass Loss ◽  
Globular Clusters ◽  
Gamma Ray ◽  
Massive Stars ◽  
Mass Range ◽  
Stellar Winds ◽  
Mass Limit ◽  
Stellar Mergers

One of the key questions in Astrophysics concerns the issue of whether there exists an upper-mass limit to stars, and if so, what physical mechanism sets this limit? The answer to this question might also determine if the upper-mass limit is metallicity (Z) dependent. We argue that mass loss by radiation-driven winds mediated by line opacity is one of the prime candidates setting the upper-mass limit. We present mass-loss predictions (Ṁwind) from Monte Carlo radiative transfer models for relatively cool (Teff = 15 kK) very inflated massive stars (VMS) with large Eddington Γ factors in the mass range 102–103 M⊙ as a function of metallicity down to 1/100 Z∕Z⊙. We employed a hydrodynamic version of our Monte Carlo method, allowing us to predict the rate of mass loss (Ṁwind) and the terminal wind velocity (v∞) simultaneously. Interestingly, we find wind terminal velocities (v∞) that are low (100–500 km s−1) over a wide Z-range, and we propose that the slow winds from VMS are an important source of self-enrichment in globular clusters. We also find mass-loss rates (Ṁwind), exceeding the typical mass-accretion rate (Ṁaccr) of 10−3 M⊙ yr−1 during massive-star formation. We have expressed our mass-loss predictions as a function of mass and Z, finding log Ṁ = −9.13 + 2.1 log(M∕M⊙) + 0.74 log(Z∕Z⊙) (M⊙∕yr). Even if stellar winds do not directly halt & reverse mass accretion during star formation, if the most massive stars form by stellar mergers, stellar wind mass loss may dominate over the rate at which stellar growth takes place. We therefore argue that the upper-mass limit is effectively Z-dependent due to the nature of radiation-driven winds. This has dramatic consequences for the most luminous supernovae, gamma-ray bursts, and other black hole formation scenarios at different Cosmic epochs.

scholarly journals Signatures of the core-powered mass-loss mechanism in the exoplanet population: dependence on stellar properties and observational predictions

2020 ◽  
Vol 493 (1) ◽  
pp. 792-806 ◽  
Author(s):  
Akash Gupta ◽  
Hilke E Schlichting
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Stellar Mass ◽  
Loss Mechanism ◽  
Data Set ◽  
First Order ◽  
Bolometric Luminosity ◽  
The Core ◽  
Stellar Properties ◽  
Atmospheric Mass

ABSTRACT Recent studies have shown that atmospheric mass-loss powered by the cooling luminosity of a planet’s core can explain the observed radius valley separating super-Earths and sub-Neptunes, even without photoevaporation. In this work, we investigate the dependence of this core-powered mass-loss mechanism on stellar mass (M*), metallicity (Z*), and age (τ*). Without making any changes to the underlying planet population, we find that the core-powered mass-loss model yields a shift in the radius valley to larger planet sizes around more massive stars with a slope given by dlog Rp/dlog M* ≃ 0.35, in agreement with observations. To first order, this slope is driven by the dependence of core-powered mass-loss on the bolometric luminosity of the host star and is given by dlog Rp/dlog M* ≃ (3α − 2)/36 ≃ 0.33, where (L*/L⊙) = (M*/M⊙)α is the stellar mass–luminosity relation and α ≃ 4.6 for the CKS data set. We therefore find, in contrast to photoevaporation models, no evidence for a linear correlation between planet and stellar mass, but cannot rule it out either. In addition, we show that the location of the radius valley is, to first order, independent of stellar age and metallicity. Since core-powered mass-loss proceeds over Gyr time-scales, the abundance of super-Earths relative to sub-Neptunes increases with age but decreases with stellar metallicity. Finally, due to the dependence of the envelope’s cooling time-scale on metallicity, we find that the radii of sub-Neptunes increase with metallicity and decrease with age with slopes given by dlog Rp/dlog Z* ≃ 0.1 and dlog Rp/dlog τ* ≃ −0.1, respectively. We conclude with a series of observational tests that can differentiate between core-powered mass-loss and photoevaporation models.

scholarly journals Progenitors and Hydrodynamics of Type II and lb Supernovae

1996 ◽  
Vol 145 ◽  
pp. 137-147
Author(s):  
S. E. Woosley ◽  
T. A. Weaver ◽  
R. G. Eastman
Keyword(s):  
Black Holes ◽  
Light Curve ◽  
Mass Loss ◽  
Massive Stars ◽  
The Other ◽  
Shock Interaction ◽  
Type Ii ◽  
Residual Hydrogen ◽  
Ordinary Type ◽  
The One

We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing pr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 Mʘ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and lb supernovae.

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