Progenitors Of Type IIP Supernovae Research Articles

The Explosion and Progenitor Properties of Type IIP Supernovae Inferred from MESA and STELLA Modelling.

The progenitors of Type IIP supernovae (SNe) are known to be red supergiants, but their properties are not well determined. We employ hydrodynamical modeling to investigate the explosion characteristics of eight Type IIP SNe and the properties of their progenitor stars. We create evolutionary models using the MESA stellar evolution code, explode these models, and simulate the optical light curves using the STELLA code. We fit the optical light curves, Fe II 5169 Å velocity, and photospheric velocity to the observational data. Our fits give a progenitor ZAMS mass of <19 M☉ for seven of the SNe. Where previous progenitor mass estimates exist from various sources, such as hydrodynamical modeling, multiwavelength observations, or semianalytic calculations, our modeling generally tends toward the lower-mass values. We are unable to fit one event, SN 2015ba well, but our best fit indicates a progenitor mass closer to 24 M☉.

Type IIP Supernova Progenitors. III. Blue to Red Supergiant Ratio in Low-metallicity Models with Convective Overshoot

Abstract The distribution of stars in the Hertzsprung–Russell diagram (HRD) for a stellar conglomeration represents a snapshot of its evolving stellar population. Some of the supergiant stars may transit the HRD from blue to red and then again to blue during their late evolutionary stages, as exemplified by the progenitor of SN 1987 A. Others may transit a given part of the HRD more than twice in a “blue loop” and end up as red supergiants before they explode. Since stars in blue loops spend a considerable part of their lives there, these stages may change the relative number of modeled supergiants in the HRD. Their lifetimes, in turn, depend upon the initial mass of the star, how convection in its interior is modeled, and how much mass loss takes place during its evolution. The observed ratio of the number of blue to red supergiants and yellow to red supergiants sensitively tests the stellar evolution theory. We compare modeled number ratios of these supergiants with observed data from the Large Magellanic Cloud, as it has a metallicity very similar to that of the environment of SN 2013ej. We successfully model these by taking into account moderate (exponential) convective overshooting. We explore its effect on the final radius and mass of the star prior to core collapse. The radius differs dramatically with overshoot. These factors controlling presupernova structure may affect the postexplosion optical/IR light curves and spectral development.

On the red supergiant problem

ABSTRACT We examine the problem of estimating the mass range corresponding to the observed red supergiant (RSG) progenitors of Type IIP supernovae. Using Monte Carlo simulations designed to reproduce the properties of the observations, we find that the approach of Davies &amp; Beasor significantly overestimates the maximum mass, yielding an upper limit of Mh/M⊙ = 20.5 ± 2.6 for an input population with Mh/M⊙ = 18. Our preferred Bayesian approach does better, with Mh/M⊙ = 18.6 ± 2.1 for the same input populations, but also tends to overestimate Mh. For the actual progenitor sample and a Salpeter initial mass function, we find $M_{\rm h}/\mathrm{M}_\odot = 19.01_{-2.04}^{+4.04}$ for the Eldridge &amp; Tout mass–luminosity relation used by Smartt and Davies &amp; Beasor, and $M_{\rm h}/\mathrm{M}_\odot = 21.28_{-2.28}^{+4.52}$ for the Sukhbold, Woosley &amp; Heger mass–luminosity relation. Based on the Monte Carlo simulations, we estimate that these are overestimated by $(3.3\pm 0.8)\, \mathrm{M}_\odot$. The red supergiant problem remains.

Type IIP Supernova Progenitors. II. Stellar Mass and Obscuration by the Dust in the Circumstellar Medium

Abstract It has been well established from a variety of observations that red supergiants (RSGs) lose a lot of mass in stellar wind. Dust that has formed in this emitted gas over a few decades before core-collapse can lead to substantial extinction and obscure the intrinsic luminosity of the progenitor RSG. This may lead to a difficulty in determining the range of progenitor masses that lead to the different classes of supernovae. Even nearby, well-studied supernovae with pre-explosion observations, such as SN 2013ej, may suffer from this uncertainty in the progenitor mass. We explore here two different masses proposed for its progenitor. We compute their pre-supernova characteristics using Modules for Experiments in Stellar Astrophysics. We show that a non-rotating star with an initial mass of 26 M ⊙ would require a considerable amount of circumstellar medium (A V ∼ 3) to obscure its high luminosity given the observed pre-explosion magnitudes detected by the Hubble Space Telescope (HST). Such a high value of visual extinction appears to be inconsistent with that derived for SN 2013ej as well as SN 2003gd in the same host galaxy, M74. In contrast, the evolutionary models of a lower mass (13 M ⊙) star are easily accommodated within the observed HST magnitudes. Some of the 26 M ⊙ simulations show luminosity variation in the last few years, which could be discriminated by high-cadence and multiband monitoring of supernova candidates in nearby galaxies. We demonstrate that our calculations are well resolved with adequate zoning and evolutionary time steps.

Type IIP Supernova Progenitors and Their Explodability. I. Convective Overshoot, Blue Loops, and Surface Composition

Abstract We present the evolution of massive star progenitors of supernovae of type IIP. We take the example of the nearby and well-studied SN 2013ej. We explore how convective overshoot affects the stellar structure, surface abundances, and effective temperature of massive stars, using the Modules for Experiments in Stellar Astrophysics. In particular, models with moderate overshoot (f = 0.02–0.031) show the presence of blue loops in the Hertzsprung–Russell diagram with a red to blue excursion (log10[T eff/K] from &lt;3.6 to &gt;4.0) and transition back to red, during the core helium-burning phase. Models with overshoot outside this range of f values kept the star in the red supergiant state throughout the post-helium-ignition phases. The surface CNO abundance shows enrichment post-main-sequence and again around the time when helium is exhausted in the core. These evolutionary changes in surface CNO abundance are indistinguishable in the currently available observations due to large observational uncertainties. However, these observations may distinguish between the ratio of surface nitrogen to oxygen at different evolutionary stages of the star. We also compare the effects of convective overshoot on various parameters related to likelihood of explosion of a star as opposed to collapse to a black hole. These parameters are the compactness parameter, M 4, and μ 4. The combination μ 4 × M 4, and μ 4 have similar variations with f and both peak at f = 0.032. We find that all of our 13 models are likely to explode.

Excavating the Explosion and Progenitor Properties of Type IIP Supernovae via Modeling of their Optical Light Curves.

The progenitors of Type IIP supernovae (SNe) are known to be red supergiants, but their properties are not well determined. We employ hydrodynamical modeling to investigate the explosion characteristics of eight Type IIP SNe and the properties of their progenitor stars. We create evolutionary models using the mesa stellar evolution code, explode these models, and simulate the optical light curves using the stella code. We fit the optical light curves, Fe ii 5169 Å velocity, and photospheric velocity to the observational data. Recent research has suggested that the progenitors of Type IIP SNe have a zero-age main-sequence (ZAMS) mass not exceeding ~18 M ⊙. Our fits give a progenitor ZAMS mass of ⩽18 M ⊙ for seven of the SNe. Where previous progenitor mass estimates exist from various sources, such as hydrodynamical modeling, multiwavelength observations, or semi-analytic calculations, our modeling generally tends toward the lower-mass values. This result is in contrast to results from previous hydrodynamical modeling but consistent with those obtained using general-relativistic radiation-hydrodynamical codes. We do find that one event, SN 2015ba, has a progenitor whose mass is closer to 24 M ⊙, although we are unable to fit it well. We also derive the amount of 56Ni required to reproduce the tail of the light curve and find values generally larger than previous estimates. Overall, we find that it is difficult to characterize the explosion by a single parameter, and that a range of parameters is needed.

Evolutionary Models of Red Supergiants: Evidence for A Metallicity-dependent Mixing Length and Implications for Type IIP Supernova Progenitors

Abstract Recent studies on the temperatures of red supergiants (RSGs) in the local universe provide us with an excellent observational constraint on RSG models. We calibrate the mixing length parameter by comparing model predictions with the empirical RSG temperatures in Small and Large Magellanic Clouds, Milky Way, and M31, which are inferred from the TiO band and the spectral energy distribution (SED). Although our RSG models are computed with the MESA code, our result may be applied to other stellar evolution codes, including the BEC and TWIN codes. We find evidence that the mixing length increases with increasing metallicity for both cases where the TiO and SED temperatures of RSGs are used for the calibration. Together with the recent finding of a similar correlation in low-mass red giants by Tayar et al., this implies that the metallicity dependence of the mixing length is a universal feature in post-main sequence stars of both low and high masses. Our result implies that typical Type IIP supernova (SN IIP) progenitors with initial masses of have a radius range of regardless of metallicity. As an auxiliary result of this study, we find that the hydrogen-rich envelope mass of SN IIP progenitors for a given initial mass is predicted to be largely independent of metallicity if the Ledoux criterion with slow semiconvection is adopted, while the Schwarzschild models predict systematically more massive hydrogen-rich envelopes for lower metallicity.

Red supergiants as supernova progenitors.

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'.

Unveiling the structure of the progenitors of type-IIP Supernovae through multi-waveband observations

AbstractObservational evidence from archival, pre-explosion images, suggests that progenitors of type-IIP SNe (SNe-IIP) have 8 ⩽MP⩽ 17M⊙. However, the post-explosion temporal evolution of the event suggests that even in this mass range, the stellar evolutionary paths, the ensuing mass loss, and the eventual interaction of the supernova shock with the resulting CSM can show considerable diversity. Here we present the results from our program on multi-waveband (mainly optical) observations of SNe-IIP. Mass loss in their progenitors, with a massive and extended H-envelopes, is seen to occur via both strong stellar winds, or episodic mass ejections. Moreover, some type-IIP SNe also show unusually steep decline, characteristic of type-IIL (e.g. SN-IIP 2013ej). Our early and late-time spectrophotometry of these events shows CSM- shock interaction to varying degree among progenitors of comparable mass. Combined with X-ray data, our findings suggest that SNe-IIP progenitors can lose mass via strong stellar winds (e.g. SN2013ej, and SN2014cx), have episodic mass loss (SN2011ja), or have negligible mass loss (SN2012aw, SN2013ab).

The evolution of red supergiants to supernova in NGC 2100

The mass loss rates of red supergiants (RSGs) govern their evolution towards supernova and dictate the appearance of the resulting explosion. To study how mass-loss rates change with evolution we measure the mass-loss rates (\mdot) and extinctions of 19 red supergiants in the young massive cluster NGC2100 in the Large Magellanic Cloud. By targeting stars in a coeval cluster we can study the mass-loss rate evolution whilst keeping the variables of mass and metallicity fixed. Mass-loss rates were determined by fitting DUSTY models to mid-IR photometry from WISE and Spitzer/IRAC. We find that the \mdot\ in red supergiants increases as the star evolves, and is well described by \mdot\ prescription of de Jager, used widely in stellar evolution calculations. We find the extinction caused by the warm dust is negligible, meaning the warm circumstellar material of the inner wind cannot explain the higher levels of extinction found in the RSGs compared to other cluster stars. We discuss the implications of this work in terms of supernova progenitors and stellar evolution theory. We argue there is little justification for substantially increasing the \mdot\ during the RSG phase, as has been suggested recently in order to explain the absence of high mass Type IIP supernova progenitors. We also argue that an increase in reddening towards the end of the RSG phase, as observed for the two most evolved cluster stars, may provide a solution to the red supergiant problem.

Red Supergiant Stars as Supernova Progenitors – the X-ray Perspective

AbstractRed Supergiants (RSGs) have for decades been assumed to be the progenitors of Type IIP supernovae (SNe). They are expected to have dense winds with mass-loss rates up to 10−4 M⊙ yr−1. We have created a database of available X-ray lightcurves of SNe. Type IIP SNe are found to have the lowest X-ray luminosities among all classes, which is surprising given the high mass-loss rate winds expected from their red supergiant progenitors, and therefore the high density medium into which Type IIP SNe are expected to expand into. We show that the low X-ray luminosity sets a limit on the mass-loss rate of the progenitor star which can collapse to become a RSG, which is about 10−5 M⊙ yr−1. This in turn can be used to set a limit on the initial mass of a RSG star which can become a Type IIP progenitor, which is about 19 M⊙. This is consistent with the limit obtained via direct optical progenitor identification. Optically identified progenitors of Type IIP SNe are found to be RSGs with masses less than about 17 M⊙ (Smartt (2009)). We discuss the implications of this result for stellar evolution, theorize on the fate of RSG stars with initial mass &gt; 19 M⊙, and discuss what type of SNe they will produce at the end of their lifetime.

The red supergiant and supernova rate problems: implications for core-collapse supernova physics

Abstract Mapping supernovae to their progenitors is fundamental to understanding the collapse of massive stars. We investigate the red supergiant problem, which concerns why red supergiants with masses ∼16–30 M⊙ have not been identified as progenitors of Type IIP supernovae, and the supernova rate problem, which concerns why the observed cosmic supernova rate is smaller than the observed cosmic star formation rate. We find key physics to solving these in the compactness parameter, which characterizes the density structure of the progenitor. If massive stars with compactness above ξ2.5 ∼ 0.2 fail to produce canonical supernovae, (i) stars in the mass range 16–30 M⊙ populate an island of stars that have high ξ2.5 and do not produce canonical supernovae, and (ii) the fraction of such stars is consistent with the missing fraction of supernovae relative to star formation. We support this scenario with a series of two- and three-dimensional radiation hydrodynamics core-collapse simulations. Using more than 300 progenitors covering initial masses 10.8–75 M⊙ and three initial metallicities, we show that high compactness is conducive to failed explosions. We then argue that a critical compactness of ∼0.2 as the divide between successful and failed explosions is consistent with state-of-the-art three-dimensional core-collapse simulations. Our study implies that numerical simulations of core collapse need not produce robust explosions in a significant fraction of compact massive star initial conditions.

FAILED SUPERNOVAE EXPLAIN THE COMPACT REMNANT MASS FUNCTION

One explanation for the absence of higher mass red supergiants (16.5 Msun < M < 25Msun) as the progenitors of Type IIP supernovae (SNe) is that they die in failed SNe creating black holes. Simulations show that such failed SNe still eject their hydrogen envelopes in a weak transient, leaving a black hole with the mass of the star's helium core (5-8Msun). Here we show that this naturally explains the typical masses of observed black holes and the gap between neutron star and black hole masses without any fine-tuning of the SN mechanism beyond having it fail in a mass range where many progenitor models have density structures that make the explosions more likely to fail. There is no difficulty including this ~20% population of failed SNe in any accounting of SN types over the progenitor mass function. And, other than patience, there is no observational barrier to either detecting these black hole formation events or limiting their rates to be well below this prediction.

LUMINOUS AND VARIABLE STARS IN M31 AND M33. I. THE WARM HYPERGIANTS AND POST-RED SUPERGIANT EVOLUTION

The progenitors of Type IIP supernovae have an apparent upper limit to their initial masses of about 20 solar masses, suggesting that the most massive red supergiants evolve to warmer temperatures before their terminal explosion. But very few post-red supergiants are known. We have identified a small group of luminous stars in M31 and M33 that are candidates for post-red supergiant evolution. These stars have A -- F-type supergiant absorption line spectra and strong hydrogen emission. Their spectra are also distinguished by the Ca II triplet and [Ca II] doublet in emission formed in a low density circumstellar environment. They all have significant near- and mid-infrared excess radiation due to free-free emission and thermal emission from dust. We estimate the amount of mass they have shed and discuss their wind parameters and mass loss rates which range from a few times$ 10^-6 to 10^-4 solar masses/yr. On an HR Diagram, these stars will overlap the region of the LBVs at maximum light, however the warm hypergiants are not LBVs. Their non-spherical winds are not optically thick and they have not exhibited any significant variability. We suggest, however, that the warm hypergiants may be the progenitors of the "less luminous" LBVs such as R71 and even SN1987A.

Circumstellar dust as a solution to the red supergiant supernova progenitor problem

We investigate the red supergiant problem: the apparent dearth of Type IIP supernova progenitors with masses between 16 and 30 M_sun. Although red supergiants with masses in this range have been observed, none have been identified as progenitors in pre-explosion images. We show that by failing to take into account the additional extinction resulting from the dust produced in the red supergiant winds, we risk underestimating the luminosity of the most massive red supergiants at the end of their lives. We estimate the initial masses of all Type IIP progenitors for which observations exist and analyse the resulting population. We find that the most likely maximum mass for a Type IIP progenitor is 21^{+2}_{-1} M_sun. This is in closer agreement with the limit predicted from single star evolution models.

Ultraviolet-Bright Type IIP Supernovae from Massive Red Supergiants

AbstractRed supergiants (RSGs) are progenitors of Type IIP supernovae (SNe). It is suggested that RSGs can experience a mass loss with a very high mass-loss rate (even as high as 0.01 M⊙ yr−1) due to, e.g., dynamical instabilities of their envelopes (e.g., Yoon &amp; Cantiello (2010)). Because of the extensive mass loss, RSGs can have very dense circumstellar medium (CSM) around them. If a SN explosion occurs soon after the extensive mass loss of a RSG, the SN ejecta will collide with the dense CSM. Due to the collision, the kinetic energy of the ejecta is converted to radiation energy and such SNe with collision can be brighter than usual Type IIP SNe. By performing one-dimensional multi-group radiation hydrodynamical calculations, we investigate the effects of the collision on Type IIP SN LCs. We show that if RSGs explode within a dense CSM, the SN will be very bright, especially in ultraviolet, at early epochs. We also compare our models with the ultraviolet-bright Type IIP SN 2009kf and show that the progenitor of SN 2009kf can be a massive RSG which experienced extensive mass loss just before its explosion. We conclude that this is evidence that massive RSGs experience extensive mass loss and the existence of such mass loss can actually be the cause of the contradiction between theoretical and observational mass ranges of Type IIP SN progenitors.

The Red Supergiant Problem: Circumstellar dust as a solution

AbstractWe investigate the red supergiant problem: the apparent dearth of Type IIP supernova progenitors with masses between 16 and 30 M⊙. Although red supergiants with masses in this range have been observed, none have been identified as progenitors in pre–explosion images. We show that, by failing to take into account the additional extinction resulting from the dust produced in the red supergiant winds, the luminosity of the most massive red supergiants at the end of their lives is underestimated. We re–estimate the initial masses of all Type IIP progenitors for which observations exist and analyse the resulting population. We find that the most likely maximum mass for a Type IIP progenitor is 21+2−1 M⊙. This is in closer agreement with the limit predicted from single star evolution models.

EVOLUTION OF MASSIVE STARS WITH PULSATION-DRIVEN SUPERWINDS DURING THE RED SUPERGIANT PHASE

Pulsations driven by partial ionization of hydrogen in the envelope are often considered important for driving winds from red supergiants (RSGs). In particular, it has been suggested by some authors that the pulsation growth rate in a RSG can be high enough to trigger an unusually strong wind (or a super-wind), when the luminosity to mass ratio becomes sufficiently large. Using both hydrostatic and hydrodynamic stellar evolution models with initial masses ranging from 15 to 40 \Msun, we investigate 1) how the pulsation growth rate depends on the global parameters of supergiant stars, and 2) what would be the consequences of a pulsation-driven super-wind, if it occurred, for the late stages of massive star evolution. We suggest that such a super-wind history would be marked by a runaway increase, followed by a sudden decrease, of the winds mass loss rate. The impact on the late evolution of massive stars would be substantial, with stars losing a huge fraction of their H-envelope even with a significantly lower initial mass than previously predicted. This might explain the observed lack of Type II-P supernova progenitors having initial mass higher than about 17 \Msun. We also discuss possible implications for a subset of Type IIn supernovae.

The death of massive stars - I. Observational constraints on the progenitors of Type II-P supernovae

We present the results of a 10.5-yr, volume-limited (28-Mpc) search for supernova (SN) progenitor stars. In doing so we compile all SNe discovered within this volume (132, of which 27 per cent are Type Ia) and determine the relative rates of each subtype from literature studies. The core-collapse SNe break down into 59 per cent II-P and 29 per cent Ib/c, with the remainder being IIb (5 per cent), IIn (4 per cent) and II-L (3 per cent). There have been 20 II-P SNe with high-quality optical or near-infrared pre-explosion images that allow a meaningful search for the progenitor stars. In five cases they are clearly red supergiants, one case is unconstrained, two fall on compact coeval star clusters and the other twelve have no progenitor detected. We review and update all the available data for the host galaxies and SN environments (distance, metallicity and extinction) and determine masses and upper mass estimates for these 20 progenitor stars using the STARS stellar evolutionary code and a single consistent homogeneous method. A maximum likelihood calculation suggests that the minimum stellar mass for a Type II-P to form is mmin= 8.5+1−1.5 M⊙ and the maximum mass for II-P progenitors is mmax= 16.5 ± 1.5 M⊙, assuming a Salpeter initial mass function holds for the progenitor population (in the range Γ=−1.35+0.3−0.7). The minimum mass is consistent with current estimates for the upper limit to white dwarf progenitor masses, but the maximum mass does not appear consistent with massive star populations in Local Group galaxies. Red supergiants in the Local Group have masses up to 25 M⊙ and the minimum mass to produce a Wolf–Rayet star in single star evolution (between solar and LMC metallicity) is similarly 25–30 M⊙. The reason we have not detected any high-mass red supergiant progenitors above 17 M⊙ is unclear, but we estimate that it is statistically significant at 2.4σ confidence. Two simple reasons for this could be that we have systematically underestimated the progenitor masses due to dust extinction or that stars between 17–25 M⊙ produce other kinds of SNe which are not II-P. We discuss these possibilities and find that neither provides a satisfactory solution. We term this discrepancy the ‘red supergiant problem’ and speculate that these stars could have core masses high enough to form black holes and SNe which are too faint to have been detected. We compare the 56Ni masses ejected in the SNe to the progenitor mass estimates and find that low-luminosity SNe with low 56Ni production are most likely to arise from explosions of low-mass progenitors near the mass threshold that can produce a core-collapse.

Supernovae and their Evolution in a Low Metallicity ISM

AbstractObservations of core collapse supernovae and their progenitors generally support expectations of increasing mass loss with increasing initial mass. Mass loss rates are expected to decline at lower metallicity, and there are prospects for directly testing this for the red supergiant progenitors of Type IIP supernovae. However, there are indications that mass loss rates for high mass early type stars may be overestimated and that there are mass loss mechanisms that do not decline at lower metallicity. In this case, there may be supernova emission from strong circumstellar interaction even at low metallicity. Although there is evidence for dust formation in freely expanding ejecta of supernovae, the quantities are relatively small. Another promising site of dust formation is the circumstellar interaction region, but this should occur in only a fraction of supernovae.