scholarly journals Outbursts from evolved massive stars: SN 2015bh and its relatives

2017 ◽  
Vol 12 (S331) ◽  
pp. 33-38
Author(s):  
Christina C. Thöne ◽  
Antonio de Ugarte Postigo ◽  
Jose Groh
Keyword(s):  
Stellar Evolution ◽  
Large Scale ◽  
Massive Stars ◽  
Core Collapse ◽  
Outer Envelope ◽  
Sn 1987A ◽  
Late Stages ◽  
Rayet Star ◽  
Insight Into ◽  
High Cadence

AbstractIn their final stages, massive stars can show large eruptions which can resemble core-collapse IIn SNe. Here we present SN 2015bh in NGC 2770, a IIn/impostor, where archival data show variabilities for at least 21 years before the main event in 2015. Serendipitous spectra during an outburst are the only SN progenitor spectra available since SN 1987A and show an LBV with a fast, dense outflow. Analogues to SN 2015bh are SN 2009ip and SNhunt 248 while the SN 2000ch impostor could be equivalent to the outburst phase of SN 2015bh. It is currently unclear whether SN 2015bh (and SN 2009ip) were final core-collapse events. Alternatively, they might be large outbursts shedding the outer envelope and creating a Wolf-Rayet star in only a matter of decades. Future large-scale high-cadence surveys such as LSST will detect many more of these events and allow us a unique insight into the largely unknown late stages of massive stellar evolution.

scholarly journals A shallow water analogue of asymmetric core-collapse, and neutron star kick/spin

2011 ◽  
Vol 7 (S279) ◽  
pp. 134-137
Author(s):  
Thierry Foglizzo ◽  
Frédéric Masset ◽  
Jérôme Guilet ◽  
Gilles Durand
Keyword(s):  
Neutron Star ◽  
Shallow Water ◽  
Acoustic Waves ◽  
Large Scale ◽  
Massive Stars ◽  
Core Collapse ◽  
Hydraulic Jumps ◽  
Core Collapse Supernova ◽  
Accretion Shock

AbstractMassive stars end their life with the gravitational collapse of their core and the formation of a neutron star. Their explosion as a supernova depends on the revival of a spherical accretion shock, located in the inner 200km and stalled during a few hundred milliseconds. Numerical simulations suggest that the large scale asymmetry of the neutrino-driven explosion is induced by a hydrodynamical instability named SASI. Its non radial character is able to influence the kick and the spin of the resulting neutron star. The SWASI experiment is a simple shallow water analog of SASI, where the role of acoustic waves and shocks is played by surface waves and hydraulic jumps. Distances in the experiment are scaled down by a factor one million, and time is slower by a factor one hundred. This experiment is designed to illustrate the asymmetric nature of core-collapse supernova.

scholarly journals The Impact of Realistic Red Supergiant Mass Loss on Stellar Evolution

2021 ◽  
Vol 922 (1) ◽  
pp. 55
Author(s):  
Emma R. Beasor ◽  
Ben Davies ◽  
Nathan Smith
Keyword(s):  
Mass Loss ◽  
Stellar Evolution ◽  
Massive Stars ◽  
Light Curves ◽  
Core Collapse ◽  
Strong Impact ◽  
Type Ii ◽  
Evolutionary Models ◽  
Cool Star ◽  
The Impact

Abstract Accurate mass-loss rates are essential for meaningful stellar evolutionary models. For massive single stars with initial masses between 8 and 30M ⊙the implementation of cool supergiant mass loss in stellar models strongly affects the resulting evolution, and the most commonly used prescription for these cool-star phases is that of de Jager. Recently, we published a new M ̇ prescription calibrated to RSGs with initial masses between 10 and 25 M ⊙, which unlike previous prescriptions does not overestimate M ̇ for the most massive stars. Here, we carry out a comparative study to the MESA-MIST models, in which we test the effect of altering mass loss by recomputing the evolution of stars with masses 12–27 M ⊙ with the new M ̇ -prescription implemented. We show that while the evolutionary tracks in the HR diagram of the stars do not change appreciably, the mass of the H-rich envelope at core collapse is drastically increased compared to models using the de Jager prescription. This increased envelope mass would have a strong impact on the Type II-P SN lightcurve, and would not allow stars under 30 M ⊙ to evolve back to the blue and explode as H-poor SN. We also predict that the amount of H-envelope around single stars at explosion should be correlated with initial mass, and we discuss the prospects of using this as a method of determining progenitor masses from supernova light curves.

scholarly journals The Supernova/GRB Connection

2005 ◽  
Vol 192 ◽  
pp. 403-410 ◽  
Author(s):  
P. Höflich ◽  
D. Baade ◽  
A. Khokhlov ◽  
L. Wang ◽  
J.C. Wheeler
Keyword(s):  
Black Hole ◽  
Neutron Star ◽  
Central Region ◽  
Stellar Evolution ◽  
Axial Symmetry ◽  
Energy Deposition ◽  
Gamma Ray ◽  
Massive Stars ◽  
Core Collapse ◽  
Supernova Explosions

SummaryWe discuss the possible connection between supernova explosions (SN) and gamma-ray bursters (GRB) from the perspective of our current understanding of SN physics. Core collapse supernovae (SN) are the final stages of stellar evolution in massive stars during which the central region collapses, forms a neutron star (NS) or black hole, and the outer layers are ejected. Recent explosion scenarios assumed that the ejection is due to energy deposition by neutrinos into the envelope but detailed models do not produce powerful explosions. There is new and mounting evidence for an asphericity and, in particular, for axial symmetry in several supernovae which may be hard to reconcile within the spherical picture. The 3-D signatures are a key to understand core collapse supernovae and the GRB/SN connection. In this paper we study the effects and observational consequences of asymmetric explosions.

scholarly journals Blue supergiant progenitors from binary mergers for SN 1987A and other Type II-peculiar supernovae

2016 ◽  
Vol 12 (S329) ◽  
pp. 64-68
Author(s):  
Athira Menon ◽  
Alexander Heger
Keyword(s):  
Stellar Evolution ◽  
Evolutionary Model ◽  
Iron Core ◽  
Core Collapse ◽  
Type Ii ◽  
Sn 1987A ◽  
Ring Nebula ◽  
Binary Mergers ◽  
Evolution Study ◽  
Different Depths

AbstractWe present results of a systematic and detailed stellar evolution study of binary mergers for blue supergiant (BSG) progenitors of Type II supernovae, particularly for SN 1987A. We are able to reproduce nearly all observational aspects of the progenitor of SN 1987A, Sk –69 °202, such as its position in the HR diagram, the enrichment of helium and nitrogen in the triple-ring nebula and its lifetime before its explosion. We build our evolutionary model based on the merger model of Podsiadlowski et al. (1992), Podsiadlowski et al. (2007) and empirically explore an initial parameter consisting of primary masses, secondary masses and different depths up to which the secondary penetrates the He core during the merger. The evolution of the post-merger star is continued until just before iron-core collapse. Of the 84 pre-supernova models (16 M⊙ − 23 M⊙) computed, the majority of the pre-supernova models are compact, hot BSGs with effective temperature >12 kK and 30 R⊙ − 70 R⊙ of which six match nearly all the observational properties of Sk –69 °202.

scholarly journals Spectropolarimetry of stripped-envelope supernovae: observations and modelling

2017 ◽  
Vol 375 (2105) ◽  
pp. 20160273 ◽  
Author(s):  
Masaomi Tanaka
Keyword(s):  
Large Scale ◽  
Massive Stars ◽  
Three Dimensional ◽  
Core Collapse ◽  
Ion Distribution ◽  
Typical Size ◽  
Cassiopeia A ◽  
Accretion Shock

Spectropolarimetry is one of the most powerful methods to study the multi-dimensional geometry of supernovae (SNe). We present a brief summary of the spectropolarimetric observations of stripped-envelope core-collapse SNe. Observations indicate that stripped-envelope SNe generally have a non-axisymmetric ion distribution in the ejecta. Three-dimensional clumpy geometry nicely explains the observed properties. A typical size of the clumps deduced from observations is relatively large: 25% of the photosphere. Such a large-scale clumpy structure is similar to that observed in Cassiopeia A, and suggests that large-scale convection or standing accretion shock instability takes place at the onset of the explosion. This article is part of the themed issue ‘Bridging the gap: from massive stars to supernovae’.

scholarly journals Evidence for Stellar Evolution in Mira Variables

1998 ◽  
Vol 11 (1) ◽  
pp. 356-356
Author(s):  
Patricia A Whitelock
Keyword(s):  
Mass Loss ◽  
Real Time ◽  
Time Evolution ◽  
Stellar Evolution ◽  
Evolutionary Status ◽  
Late Type ◽  
Chemical Changes ◽  
Mira Variables ◽  
Late Stages ◽  
Insight Into

After briefly reviewing our understanding of Miras and their evolutionary status, three aspects of real-time evolution in these and related stars are examined: 1.Chemical changes (O-rich to C-rich) due to third dredge-up,2.Period changes due to the effects of the helium shell-flash,3.The existence of ‘fossil’ dust and gas shells. Studies of resolved gas and dust shells are highlighted as particularly interesting. They will enable us to examine the mass-loss histories of many late-type stars over the last ten thousand years or so. Such observations have only recently become technically feasible and they are expected to provide important new insight into the late stages of stellar evolution.

scholarly journals The quest for blue supergiants: Evolution of binary merger progenitors of Type-II peculiar supernovae and SN 1987A

2015 ◽  
Vol 11 (A29B) ◽  
pp. 460-460
Author(s):  
Athira Menon ◽  
Alexander Heger
Keyword(s):  
Stellar Evolution ◽  
Effective Temperature ◽  
Light Curves ◽  
Core Collapse ◽  
Type Ii ◽  
Sn 1987A ◽  
C And N

AbstractWe construct stellar evolution models until core collapse using KEPLER (Woosley & Heger (2007)) to reproduce the observed signatures of the blue supergiant (BSG) progenitor of SN 1987A. This is based on the binary merger scenario proposed by Podsiadlowski (1992) and Ivanova et al. (2002). Various combinations of initial parameters for the binary components (M1=16–18 M⊙ and M2=5–10 M⊙) and their merging, successfully match the He, N/C and N/O ratios, along with the luminosity and effective temperature of the progenitor. Most of our models end their lives as BSGs. Thus we may be able to explain the origin of all Type IIP SNe that resemble SN 1987A through such mergers. We are currently working on the light curves and nuclear yields from the explosion of these models to compare them SN 1987A.

scholarly journals Wolf-Rayet stars as a diagnostic of internal mixing processes in massive mass losing stars

1988 ◽  
Vol 108 ◽  
pp. 90-91
Author(s):  
N. Langer
Keyword(s):  
Observational Data ◽  
Stellar Evolution ◽  
Chemical Structure ◽  
Large Scale ◽  
Massive Stars ◽  
The Other ◽  
Large Uncertainty ◽  
Mixing Processes ◽  
Internal Mixing ◽  
Convective Core

Massive stars (MZAMS ≳ 30 M⊙) develop during their observable hydrostatic evolutionary phases — i.e. central H- and He-burning — three different large scale convective zones, which are: 1) The H-burning convective core, 2) the intermediate convective shell (ICZ) above the hydrogen shell source, which forms at time of hydrogen exhaustion, and 3) the He-burning convective core. The spatial extent of these convective regions, wherein the chemical structure is rapidly homogenised, can be predicted from theory only with a large uncertainty. Different assumptions on the efficiency of these mixing processes in stellar evolution calculations lead to quite different evolutionary pictures for massive stars, especially regarding their Wolf-Rayet (WR) phases. On the other side, many observational data concerning WR stars became available in recent years. For this reason, we attempt to perform a comparison of theoretical evolutionary sequences with observed properties of WR stars in order to derive restrictions on the efficiency of the three mixing processes mentioned above.

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 Magnetic Fields in Stars: Origin and Impact

2013 ◽  
Vol 9 (S302) ◽  
pp. 1-9 ◽  
Author(s):  
N. Langer
Keyword(s):  
Magnetic Fields ◽  
Differential Rotation ◽  
Large Scale ◽  
Massive Stars ◽  
High Mass ◽  
Binary Interaction ◽  
Small Scale ◽  
Core Collapse ◽  
Intermediate Mass ◽  
Supernova Explosions

AbstractVarious types of magnetic fields occur in stars: small scale fields, large scale fields, and internal toroidal fields. While the latter may be ubiquitous in stars due to differential rotation, small scale fields (spots) may be associated with envelop convection in all low and high mass stars. The stable large scale fields found in only about 10% of intermediate mass and massive stars may be understood as a consequence of dynamical binary interaction, e.g., the merging of two stars in a binary. We relate these ideas to magnetic fields in white dwarfs and neutron stars, and to their role in core-collapse and thermonuclear supernova explosions.

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