scholarly journals Red supergiants as supernova progenitors

2017 ◽  
Vol 375 (2105) ◽  
pp. 20160270 ◽  
Author(s):  
Ben Davies
Keyword(s):  
Mass Spectrum ◽  
Physical Properties ◽  
Evolutionary Theory ◽  
Massive Stars ◽  
Red Supergiants ◽  
Physical Quantities ◽  
Appearance Changes

It is now well-established from pre-explosion imaging that red supergiants (RSGs) are the direct progenitors of Type-IIP supernovae. These images have been used to infer the physical properties of the exploding stars, yielding some surprising results. In particular, the differences between the observed and predicted mass spectrum has provided a challenge to our view of stellar evolutionary theory. However, turning what is typically a small number of pre-explosion photometric points into the physical quantities of stellar luminosity and mass requires a number of assumptions about the spectral appearance of RSGs, as well as their evolution in the last few years of life. Here I will review what we know about RSGs, with a few recent updates on how they look and how their appearance changes as they approach supernova. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals The Physical Properties of Red Supergiants: Comparing Theory and Observations

2007 ◽  
Vol 3 (S250) ◽  
pp. 97-110 ◽  
Author(s):  
Philip Massey ◽  
Emily M. Levesque ◽  
Bertrand Plez ◽  
Knut A. G. Olsen
Keyword(s):  
Physical Properties ◽  
Milky Way ◽  
Massive Stars ◽  
Stellar Atmospheres ◽  
Circumstellar Dust ◽  
Evolutionary Models ◽  
Dust Source ◽  
Look Back ◽  
Red Supergiants ◽  
Effective Temperatures

AbstractRed supergiants (RSGs) are an evolved stage in the life of intermediate massive stars (≤ 25 M⊙). For many years, their location in the H-R diagram was at variance with the evolutionary models. Using the MARCS stellar atmospheres, we have determined new effective temperatures and bolometric luminosities for RSGs in the Milky Way, LMC, and SMC, and our work has resulted in much better agreement with the evolutionary models. We have also found evidence of significant visual extinction due to circumstellar dust. Although in the Milky Way the RSGs contribute only a small fraction (< 1%) of the dust to the interstellar medium (ISM), in starburst galaxies or galaxies at large look-back times, we expect that RSGs may be the main dust source. We are in the process of extending this work now to RSGs of higher and lower metallicities using the galaxies M31 and WLM.

scholarly journals The R136 star cluster dissected with Hubble Space Telescope/STIS – II. Physical properties of the most massive stars in R136

2020 ◽  
Vol 499 (2) ◽  
pp. 1918-1936 ◽  
Author(s):  
Joachim M Bestenlehner ◽  
Paul A Crowther ◽  
Saida M Caballero-Nieves ◽  
Fabian R N Schneider ◽  
Sergio Simón-Díaz ◽  
...  
Keyword(s):  
Physical Properties ◽  
Hubble Space Telescope ◽  
Massive Stars ◽  
Mass Function ◽  
Large Magellanic Cloud ◽  
Spectroscopic Studies ◽  
Initial Mass Function ◽  
Space Telescope ◽  
Power Law Exponent ◽  
Red Supergiants

ABSTRACT We present an optical analysis of 55 members of R136, the central cluster in the Tarantula Nebula of the Large Magellanic Cloud. Our sample was observed with STIS aboard the Hubble Space Telescope, is complete down to about 40 M⊙, and includes seven very massive stars with masses over 100 M⊙. We performed a spectroscopic analysis to derive their physical properties. Using evolutionary models, we find that the initial mass function of massive stars in R136 is suggestive of being top-heavy with a power-law exponent γ ≈ 2 ± 0.3, but steeper exponents cannot be excluded. The age of R136 lies between 1 and 2 Myr with a median age of around 1.6 Myr. Stars more luminous than log L/L⊙ = 6.3 are helium enriched and their evolution is dominated by mass-loss, but rotational mixing or some other form of mixing could be still required to explain the helium composition at the surface. Stars more massive than 40 M⊙ have larger spectroscopic than evolutionary masses. The slope of the wind–luminosity relation assuming unclumped stellar winds is 2.41 ± 0.13 which is steeper than usually obtained (∼1.8). The ionizing ($\log Q_0\, [{\rm ph/s}] = 51.4$) and mechanical ($\log L_{\rm SW}\, [{\rm erg/s}] = 39.1$) output of R136 is dominated by the most massive stars ($\gt 100\, \mathrm{ M}_{\odot }$). R136 contributes around a quarter of the ionizing flux and around a fifth of the mechanical feedback to the overall budget of the Tarantula Nebula. For a census of massive stars of the Tarantula Nebula region, we combined our results with the VLT-FLAMES Tarantula Survey plus other spectroscopic studies. We observe a lack of evolved Wolf–Rayet stars and luminous blue and red supergiants.

scholarly journals Predicting the nature of supernova progenitors

2017 ◽  
Vol 375 (2105) ◽  
pp. 20170219 ◽  
Author(s):  
Jose H. Groh
Keyword(s):  
High Resolution ◽  
Physical Properties ◽  
Stellar Evolution ◽  
Massive Stars ◽  
High Resolution Spectrum ◽  
Core Collapse ◽  
Single Star ◽  
Luminous Blue Variables ◽  
Star Models ◽  
Red Supergiants

Stars more massive than about 8 solar masses end their lives as a supernova (SN), an event of fundamental importance Universe-wide. The physical properties of massive stars before the SN event are very uncertain, both from theoretical and observational perspectives. In this article, I briefly review recent efforts to predict the nature of stars before death, in particular, by performing coupled stellar evolution and atmosphere modelling of single stars in the pre-SN stage. These models are able to predict the high-resolution spectrum and broadband photometry, which can then be directly compared with the observations of core-collapse SN progenitors. The predictions for the spectral types of massive stars before death can be surprising. Depending on the initial mass and rotation, single star models indicate that massive stars die as red supergiants, yellow hypergiants, luminous blue variables and Wolf–Rayet stars of the WN and WO subtypes. I finish by assessing the detectability of SN Ibc progenitors. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals The properties of early-type stars in the Magellanic Clouds

2008 ◽  
Vol 4 (S256) ◽  
pp. 325-336
Author(s):  
Christopher J. Evans
Keyword(s):  
Physical Properties ◽  
Mass Loss ◽  
Temperature Scale ◽  
Massive Stars ◽  
Magellanic Clouds ◽  
Early Type ◽  
The Past ◽  
The Galaxy ◽  
Stellar Temperature ◽  
Early Type Stars

AbstractThe past decade has witnessed impressive progress in our understanding of the physical properties of massive stars in the Magellanic Clouds, and how they compare to their cousins in the Galaxy. I summarise new results in this field, including evidence for reduced mass-loss rates and faster stellar rotational velocities in the Clouds, and their present-day compositions. I also discuss the stellar temperature scale, emphasizing its dependence on metallicity across the entire upper-part of the Hertzsprung-Russell diagram.

scholarly journals Massive stars in their death throes

2008 ◽  
Vol 366 (1884) ◽  
pp. 4441-4452 ◽  
Author(s):  
John J Eldridge
Keyword(s):  
Stellar Evolution ◽  
Massive Stars ◽  
Evolution Theory ◽  
Luminous Blue Variables ◽  
Show Evidence ◽  
Red Supergiants ◽  
Working Backwards

The study of the stars that explode as supernovae used to be a forensic study, working backwards from the remnants of the star. This changed in 1987 when the first progenitor star was identified in pre-explosion images. Currently, there are eight detected progenitors with another 21 non-detections, for which only a limit on the pre-explosion luminosity can be placed. This new avenue of supernova research has led to many interesting conclusions, most importantly that the progenitors of the most common supernovae, type IIP, are red supergiants, as theory has long predicted. However, no progenitors have been detected thus far for the hydrogen-free type Ib/c supernovae, which, given the expected progenitors, is an unlikely result. Also, observations have begun to show evidence that luminous blue variables, which are among the most massive stars, may directly explode as supernovae. These results contradict the current stellar evolution theory. This suggests that we may need to update our understanding.

scholarly journals The Evolution of Massive Stars. I. Red Supergiants in the Magellanic Clouds

2003 ◽  
Vol 126 (6) ◽  
pp. 2867-2886 ◽  
Author(s):  
Philip Massey ◽  
K. A. G. Olsen
Keyword(s):  
Massive Stars ◽  
Magellanic Clouds ◽  
Red Supergiants

scholarly journals Formation of Orion fingers

2020 ◽  
Vol 495 (1) ◽  
pp. 1172-1187
Author(s):  
Ross Dempsey ◽  
Nadia L Zakamska ◽  
James E Owen
Keyword(s):  
Physical Properties ◽  
Time Scales ◽  
High Velocity ◽  
Massive Stars ◽  
Hydrodynamic Instabilities ◽  
Similar Time ◽  
Dynamical Interaction ◽  
Star Forming ◽  
Common System ◽  
Bow Shocks

ABSTRACT ‘Orion fingers’ are a system of dozens of bow shocks, with the wings of shocks pointing to a common system of origin, which is centred on a dynamically disintegrating system of several massive stars. The shock heads propagate with velocities of up to 300–400 km s−1, but the formation and physical properties of the ‘bullets’ leading the shocks are not known. Here, we summarize two possible scenarios for the formation of the ‘bullets’ and the resulting bow shocks (‘fingers’). In the first scenario, bullets are self-gravitating, Jupiter-mass objects that were formed rapidly and then ejected during the strong dynamical interactions of massive stars and their discs. This scenario naturally explains the similar time-scales for the outflow of bullets and for the dynamical interaction of the massive stars, but has some difficulty explaining the observed high velocities of the bullets. In the second scenario, bullets are formed via hydrodynamic instabilities in a massive, infrared-driven wind, naturally explaining the high velocities and the morphology of outflow, but the bullets are not required to be self-gravitating. The processes that created the Orion fingers are likely not unique to this particular star-forming region and may result in free-floating, high-velocity, core-less planets.

scholarly journals Massive stars burning helium: the numbers of WR stars and red supergiants in galaxies

1981 ◽  
Vol 59 ◽  
pp. 283-287
Author(s):  
A. Maeder
Keyword(s):  
Mass Loss ◽  
Massive Stars ◽  
Short Note ◽  
Evolutionary Models ◽  
Helium Burning ◽  
Red Supergiants ◽  
Low Mass ◽  
Age Sequence ◽  
Carbon Burning ◽  
Loss Rates

We have calculated evolutionary models of massive stars in the range 15-120 Mʘ from the zero-age sequence up to the end of the carbon burning stage (Maeder, 1981). Three sets of models with different mass loss rates Ṁ have been computed; the adopted parametrisation of Ṁ is fitted on the observations and thus the expression for Ṁ differs according to the location of the stars in the HRD.In this short note we concentrate on the location of the He-burning stars in the HRD. The helium burning phase, which lasts 8 to 10% of the MS phase, is spent mainly as red supergiants (RSG) and as WR stars (note that for low mass loss, the time spent as A-G supergiants becomes longer).

scholarly journals The B[e] stars

1989 ◽  
Vol 113 ◽  
pp. 117-120
Author(s):  
F.-J. Zickgraf
Keyword(s):  
Physical Properties ◽  
Stellar Wind ◽  
Main Sequence ◽  
Massive Stars ◽  
High Mass ◽  
Sequence Evolution ◽  
Two Component ◽  
Show Evidence ◽  
High Mass Loss ◽  
General Appearance

AbstractB[e] supergiants show evidence for a non-spherical two-component stellar wind. The general appearance and the physical properties of the suggested disk-like configuration are discussed. The high mass-loss rates, the surprisingly large number and the location in the H-R diagram make these stars important for the understanding of the post-main-sequence evolution of massive stars.

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