Type IIP Supernova 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☉.

A low-luminosity core-collapse supernova very similar to SN 2005cs

ABSTRACT We present observations and analysis of PSN J17292918+7542390, a low-luminosity Type II-P supernova (LL SN IIP). The observed sample of such events is still low, and their nature is still under debate. Such SNe are similar to SN 2005cs, a well-observed LL Type II-P event, having low expansion velocities, and small ejected 56Ni mass. We have developed a robust and relatively fast Monte Carlo code that fits semi-analytic models to light curves of core-collapse SNe. This allows the estimation of the most important physical parameters, like the radius of the progenitor star, the mass of the ejected envelope, the mass of the radioactive nickel synthesized during the explosion, among others. PSN J17292918+7542390 has $R_0 = 91_{-70}^{+119} \times 10^{11} \, \text{cm}$, $M_\text{ej} = 9.89_{-1.00}^{+2.10} \, \mathrm{ M}_{\odot }$, $E_{\mbox{kin}} = 0.65_{-0.18}^{+0.19} \, \text{foe}$, and $v_{\mbox{exp}} = 3332_{-347}^{+216}$ km s−1, for its progenitor radius, ejecta mass, kinetic energy, and expansion velocity, respectively. The initial nickel mass of the PSN J17292918+7542390 turned out to be $1.55_{-0.70}^{+0.75} \times 10^{-3} \, \mathrm{M}_{\odot }$. The measured photospheric velocity at the earliest observed phase is 7000 km s−1. As far as we can tell based on the small population of observed LL SNe IIP, the determined values are typical for these events.

‘On the red supergiant problem’: a rebuttal, and a consensus on the upper mass cut-off for II-P progenitors

Abstract The ‘red supergiant (RSG) problem’ describes the claim that the brightest RSG progenitors to Type II-P supernovae (SNe) are significantly fainter than RSGs in the field. This mismatch has been interpreted by several authors as being a manifestation of the mass threshold for the production of black holes (BHs), such that stars with initial masses above a cut-off of Mhi = 17 M⊙ and below 25 M⊙ will die as RSGs, but with no visible SN explosion as the BH is formed. However, we have previously cautioned that this cut-off is more likely to be higher and has large uncertainties ($M_{\rm hi}=19^{+4}_{-2}\,\mathrm{ M}_{\odot }$), meaning that the statistical significance of the RSG problem is less than 2σ. Recently, Kochanek has claimed that our work is statistically flawed, and with his analysis has argued that the upper mass cut-off is as low as Mhi = 15.7 ± 0.8 M⊙, giving the RSG problem a significance of &amp;gt;10σ. In this letter, we show that Kochanek’s low cut-off is caused by a statistical misinterpretation, and the associated fit to the progenitor mass spectrum can be ruled out at the 99.6 per cent confidence level. Once this problem is remedied, Kochanek’s best fit becomes $M_{\rm hi} =19^{+4}_{-2}\,\mathrm{ M}_{\odot }$, in excellent agreement with our work. Finally, we argue that, in the search for an RSG ‘vanishing’ as it collapses directly to a BH, any such survey would have to operate for decades before the absence of any such detection became statistically significant.

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.

First Day of Type IIP Supernova SN 2013fs: H$$\alpha$$ from Preshock Accelerated Gas

I explore the origin of an asymmetry of the H$\alpha$ emission from a circumstellar (CS) shell around type IIP supernova SN 2013fs in the spectrum taken 10.3\,h after the shock breakout. A spherical model of the H$\alpha$ emission from the CS shell that takes into account a preshock gas acceleration by the supernova radiation permits us to successfully reproduce the \ha H$\alpha$ profile. Principal factors responsible for the H$\alpha$ asymmetry are the high velocity of the accelerated CS preshock gas ($\sim 3000$\,km s$^{-1}$) and a low H$\alpha$ Sobolev optical depth in a combination with an occultation of the H$\alpha$ emission by the photosphere.

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.

Apparent Magnitude of Betelgeuse as a Type IIP Supernova

Apparent Magnitude of Betelgeuse as a Type IIP Supernova

A Massive Star’s Dying Breaths: Pulsating Red Supergiants and Their Resulting Type IIP Supernovae

Abstract Massive stars undergo fundamental mode and first overtone radial pulsations with periods of 100–1000 days as red supergiants (RSGs). At large amplitudes, these pulsations substantially modify the outer envelope’s density structure encountered by the outgoing shock wave from the eventual core collapse of these stars. Using Modules for Experiments in Stellar Astrophysics (MESA), we model the effects of fundamental mode and first overtone pulsations in the RSG envelopes and the resulting Type IIP supernovae (SNe) using MESA+STELLA. We find that, in the case of fundamental mode pulsations, SN plateau observables, such as the luminosity at day 50, L 50; time-integrated shock energy, ET; and plateau duration, t p, are consistent with radial scalings derived considering explosions of nonpulsating stars. Namely, most of the effect of the pulsation is consistent with the behavior expected for a star of a different size at the time of explosion. However, in the case of overtone pulsations, the Lagrangian displacement is not monotonic. Therefore, in such cases, excessively bright or faint SN emission at different times reflects the underdense or overdense structure of the emitting region near the SN photosphere.

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.

The Luminosity Function of Red Supergiants in M31

Abstract The mass-loss rates of red supergiant stars (RSGs) are poorly constrained by direct measurements, and yet the subsequent evolution of these stars depends critically on how much mass is lost during the RSG phase. In 2012 the Geneva evolutionary group updated their mass-loss prescription for RSGs with the result that a 20 M ⊙ star now loses 10 times more mass during the RSG phase than in the older models. Thus, higher-mass RSGs evolve back through a second yellow supergiant phase rather than exploding as Type II-P supernovae, in accord with recent observations (the so-called “RSG Problem”). Still, even much larger mass-loss rates during the RSG phase cannot be ruled out by direct measurements of their current dust-production rates, as such mass loss is episodic. Here, we test the models by deriving a luminosity function for RSGs in the nearby spiral galaxy, M31, which is sensitive to the total mass loss during the RSG phase. We carefully separate RSGs from asymptotic giant branch stars in the color–magnitude diagram following the recent method exploited by Yang and collaborators in their Small Magellanic Cloud studies. Comparing our resulting luminosity function with that predicted by the evolutionary models shows that the new prescription for RSG mass loss does an excellent job of matching the observations, and we can readily rule out significantly larger values.

Supernova 2018cuf: A Type IIP Supernova with a Slow Fall from Plateau

Abstract We present multiband photometry and spectroscopy of SN 2018cuf, a Type IIP (“P” for plateau) supernova (SN) discovered by the Distance Less Than 40 Mpc Survey within 24 hr of explosion. SN 2018cuf appears to be a typical SN IIP, with an absolute V-band magnitude of −16.73 ± 0.32 at maximum and a decline rate of 0.21 ± 0.05 mag/50 days during the plateau phase. The distance of the object was constrained to be 41.8 ± 5.7 Mpc by using the expanding photosphere method. We used spectroscopic and photometric observations from the first year after the explosion to constrain the progenitor of SN 2018cuf using both hydrodynamic light-curve modeling and late-time spectroscopic modeling. The progenitor of SN 2018cuf was most likely a red supergiant of about 14.5 M ⊙ that produced 0.04 ± 0.01 M ⊙ 56Ni during the explosion. We also found ∼0.07 M ⊙ of circumstellar material (CSM) around the progenitor is needed to fit the early light curves, where the CSM may originate from presupernova outbursts. During the plateau phase, high-velocity features at ∼11,000 km s−1 were detected in both the optical and near-infrared spectra, supporting the possibility that the ejecta were interacting with some CSM. A very shallow slope during the postplateau phase was also observed, and it is likely due to a low degree of nickel mixing or the relatively high nickel mass in the SN.

Spectral modeling of type II supernovae

There are now hundreds of publicly available supernova spectral time series. Radiative transfer modeling of this data provides insight into the physical properties of these explosions, such as the composition, the density structure, and the intrinsic luminosity, which is invaluable for understanding the supernova progenitors, the explosion mechanism, and for constraining the supernova distance. However, a detailed parameter study of the available data has been out of reach due to the high dimensionality of the problem coupled with the still significant computational expense. We tackle this issue through the use of machine-learning emulators, which are algorithms for high-dimensional interpolation. These use a pre-calculated training dataset to mimic the output of a complex code but with run times that are orders of magnitude shorter. We present the application of such an emulator to synthetic type II supernova spectra generated with the TARDIS radiative transfer code. The results show that with a relatively small training set of 780 spectra we can generate emulated spectra with interpolation uncertainties of less than one percent. We demonstrate the utility of this method by automatic spectral fitting of two well-known type IIP supernovae; as an exemplary application, we determine the supernova distances from the spectral fits using the tailored-expanding-photosphere method. We compare our results to previous studies and find good agreement. This suggests that emulation of TARDIS spectra can likely be used to perform automatic and detailed analysis of many transient classes putting the analysis of large data repositories within reach.

Изучение зависимости формы плато сверхновых типа II от металличности

We consider the effect of a change in the rate of flux decline in the U band for type II-P supernovae (SNe IIP) as a function of metallicity $Z$. Based on this effect, we propose a new method to determine the photometric redshift from the SN IIP light curve in the U band. Using the STELLA code, we have constructed model light curves in different bands for different redshifts $z = 0.0, 0.1$, and $0.3$ as the metallicity in the models decreases from $Z \sim 10^{-3}$ to $\sim 10^{-6}$. The flux in the U band is shown to reach a plateau at the lowest metallicities. We consider the influence of other parameters as well: the presupernova mass and the mass of radioactive nickel-56.

A simple model of time-dependent ionization in Type IIP supernova envelopes

ABSTRACT We propose a model kinetic system of the hydrogen atom (two levels plus continuum) under the conditions typical for atmospheres of Type IIP supernovae in the plateau stage. Despite the simplicity of this system, it describes realistically the basic properties of the complete system. Analysis shows that the ionization ‘freeze-out’ effect is always manifest at large times. We give a simple criterion for checking the statistical equilibrium of a system under the given conditions at any time. It is shown that if the system is in non-equilibrium at early times, the time-dependent effect of ionization necessarily exists. We also generalize this criterion to the case of arbitrary multilevel systems. We discuss various factors that affect the strength of the time-dependent effect in the kinetics during the photospheric phase of a supernova explosion.

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.

SN 2017gmr: An Energetic Type II-P Supernova with Asymmetries

We present high-cadence ultraviolet (UV), optical, and near-infrared (NIR) data on the luminous Type II-P supernova SN 2017gmr from hours after discovery through the first 180 days. SN 2017gmr does not show signs of narrow, high-ionization emission lines in the early optical spectra, yet the optical lightcurve evolution suggests that an extra energy source from circumstellar medium (CSM) interaction must be present for at least 2 days after explosion. Modeling of the early lightcurve indicates a ~500R$_{\odot}$ progenitor radius, consistent with a rather compact red supergiant, and late-time luminosities indicate up to 0.130 $\pm$ 0.026 M$_{\odot}$ of $^{56}$Ni are present, if the lightcurve is solely powered by radioactive decay, although the $^{56}$Ni mass may be lower if CSM interaction contributes to the post-plateau luminosity. Prominent multi-peaked emission lines of H$\alpha$ and [O I] emerge after day 154, as a result of either an asymmetric explosion or asymmetries in the CSM. The lack of narrow lines within the first two days of explosion in the likely presence of CSM interaction may be an example of close, dense, asymmetric CSM that is quickly enveloped by the spherical supernova ejecta.

Radio Emission from Supernovae in the Very Early Phase: Implications for the Dynamical Mass Loss of Massive Stars

Abstract Recent high-cadence transient surveys and rapid follow-up observations indicate that some massive stars may dynamically lose their own mass within decades before supernovae (SNe). Such a mass-loss forms “confined” circumstellar medium (CSM); a high-density material distributed only within a small radius (≲1015 cm with the mass-loss rate of 0.01 ∼ 10−4 M ⊙ yr−1). While the SN shock should trigger particle acceleration and magnetic field amplification in the “confined” CSM, synchrotron emission may be masked in centimeter wavelengths due to free–free absorption; the millimeter range can, however, be a potential new window. We investigate the time evolution of synchrotron radiation from the system of a red supergiant surrounded by the “confined” CSM, relevant to typical Type II-P SNe. We show that synchrotron millimeter emission is generally detectable, and that the signal can be used as a sensitive tracer of the nature of the “confined” CSM; it traces different CSM density parameter space than in the optical. Furthermore, our simulations show that the “confined” CSM efficiently produces secondary electrons and positrons through proton inelastic collisions, which can become main contributors to the synchrotron emission in several ten days since the SN. We predict that the synchrotron emission is detectable by ALMA, and suggest that it will provide a robust evidence of the existence of the “confined” CSM.

The Initial Mass–Final Luminosity Relation of Type II Supernova Progenitors: Hints of New Physics?

Abstract We revise the theoretical initial mass–final luminosity relation for progenitors of Type IIP and IIL supernovae. The effects of the major uncertainties, such as those due to the treatment of convection, semiconvection, rotation, mass loss, nuclear reaction rates, and neutrinos production rates, are discussed in some detail. The effects of mass transfer between components of close-binary systems are also considered. By comparing the theoretical predictions to a sample of Type II supernovae for which the initial mass of the progenitors and the pre-explosive luminosity are available, we conclude that stellar rotation may explain a few progenitors that appear brighter than expected in the case of nonrotating models. In the most extreme case, SN 2012ec, an initial rotational velocity up to 300 km s−1 is required. Alternatively, these objects could be mass-losing components of close binaries. However, most of the observed progenitors appear fainter than expected. This occurrence seems to indicate that the Compton and pair neutrino energy-loss rates, as predicted by the standard electro-weak theory, are not efficient enough and that an additional negative contribution to the stellar energy balance is required. We show that axions coupled with parameters accessible to currently planned experiments, such as IAXO and, possibly, BabyIAXO and axion-like particles, may account for the missing contribution to the stellar energy loss.

Toward Rate Estimation for Transient Surveys. I. Assessing Transient Detectability and Volume Sensitivity for iPTF

Abstract The past couple of decades have seen an emergence of transient detection facilities in various avenues of time-domain astronomy that have provided us with a rich data set of transients. The rates of these transients have implications in star formation, progenitor models, evolution channels, and cosmology measurements. The crucial component of any rate calculation is the detectability and spacetime volume sensitivity of a survey to a particular transient type as a function of many intrinsic and extrinsic parameters. Fully sampling that multidimensional parameter space is challenging. Instead, we present a scheme to assess the detectability of transients using supervised machine learning. The data product is a classifier that determines the detection likelihood of sources resulting from an image subtraction pipeline associated with time-domain survey telescopes, taking into consideration the intrinsic properties of the transients and the observing conditions. We apply our method to assess the spacetime volume sensitivity of type Ia supernovae (SNe Ia) in the intermediate Palomar Transient Factory (iPTF) and obtain the result, . With rate estimates in the literature, this volume sensitivity gives a count of 680–1160 SNe Ia detectable by iPTF, which is consistent with the archival data. With a view toward wider applicability of this technique we do a preliminary computation for long-duration type IIp supernovae (SNe IIp) and find . This classifier can be used for computationally fast spacetime volume sensitivity calculation of any generic transient type using their light-curve properties. Hence, it can be used as a tool to facilitate calculation of transient rates in a range of time-domain surveys, given suitable training sets.

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.