SNe IIP Research Articles

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.

Inferring Explosion Properties from Type II-Plateau Supernova Light Curves

Abstract We present advances in modeling Type IIP supernovae (SNe IIP) using MESA for evolution to shock breakout coupled with STELLA for generating light and radial velocity curves. Explosion models and synthetic light curves can be used to translate observable properties of SNe (such as the luminosity at day 50 and the duration of the plateau, as well as the observable quantity ET, defined as the time-weighted integrated luminosity that would have been generated if there were no 56Ni in the ejecta) into families of explosions that produce the same light curve and velocities on the plateau. These predicted families of explosions provide a useful guide toward modeling observed SNe and can constrain explosion properties when coupled with other observational or theoretical constraints. For an observed SN with a measured 56Ni mass, breaking the degeneracies within these families of explosions (ejecta mass, explosion energy, and progenitor radius) requires independent knowledge of one parameter. We expect the most common case to be a progenitor radius measurement for a nearby SN. We show that ejecta velocities inferred from the Fe ii λ5169 line measured during the majority of the plateau phase provide little additional information about explosion characteristics. Only during the initial shock cooling phase can photospheric velocity measurements potentially aid in unraveling light-curve degeneracies.

Supernova 2018aoq and a distance to Seyfert galaxy NGC 4151

We present optical photometric observations of SN 2018aoq from 2 to 100 days after explosion, and 7 spectra at epochs from 11 to 71 days. The light curves and spectra are typical for SNe II-P. As previously reported, SN 2018aoq appears to be of intermediate brightness between subluminous and normal SNe II-P. SN 2018aoq was discovered in Seyfert galaxy NGC 4151, for which the distance is uncertain. We utilised the Expanding Photosphere Method using three sets of filter combinations and velocities derived from the absorption minima of FeII lines and obtained a distance of 20.0 +-1.6 Mpc. The Standard Candle Method applied to SN 2018aoq yields a distance of 16.6 +-1.1 Mpc. Both values are consistent with the distance measurements for NGC 4151 based on geometric method.

The Type II-P Supernova 2017eaw: From Explosion to the Nebular Phase

The nearby SN 2017eaw is a Type II-P (``plateau') supernova showing early-time, moderate CSM interaction. We present a comprehensive study of this SN including the analysis of high-quality optical photometry and spectroscopy covering the very early epochs up to the nebular phase, as well as near-UV and near-infrared spectra, and early-time X-ray and radio data. The combined data of SNe 2017eaw and 2004et allow us to get an improved distance to the host galaxy, NGC 6946, as $D \sim 6.85$ $\pm 0.63$ Mpc; this fits in recent independent results on the distance of the host and disfavors the previously derived (30% shorter) distances based on SN 2004et. From modeling the nebular spectra and the quasi-bolometric light curve, we estimate the progenitor mass and some basic physical parameters for the explosion and the ejecta. Our results agree well with previous reports on a RSG progenitor star with a mass of $\sim15-16$ M$_\odot$. Our estimation on the pre-explosion mass-loss rate ($\dot{M} \sim3 \times 10^{-7} -$ $1\times 10^{-6} M_{\odot}$ yr$^{-1}$) agrees well with previous results based on the opacity of the dust shell enshrouding the progenitor, but it is orders of magnitude lower than previous estimates based on general light-curve modeling of Type II-P SNe. Combining late-time optical and mid-infrared data, a clear excess at 4.5 $\mu$m can be seen, supporting the previous statements on the (moderate) dust formation in the vicinity of SN 2017eaw.

SN 2017czd: A Rapidly Evolving Supernova from a Weak Explosion of a Type IIb Supernova Progenitor

Abstract We present optical and near-infrared observations of the rapidly evolving supernova (SN) 2017czd that shows hydrogen features. The optical light curves exhibit a short plateau phase (∼13 days in the R-band) followed by a rapid decline by 4.5 mag ∼20 days after the plateau. The decline rate is larger than those of any standard SNe, and close to those of rapidly evolving transients. The peak absolute magnitude is −16.8 mag in the V band, which is within the observed range for SNe IIP and rapidly evolving transients. The spectra of SN 2017czd clearly show the hydrogen features and resemble those of SNe IIP at first. The Hα line, however, does not evolve much with time, and it becomes similar to those in SNe IIb at the decline phase. We calculate the synthetic light curves using a SN IIb progenitor that has 16 at the zero-age main sequence and evolves into a binary system. The model with a low explosion energy (5 × 1050 erg) and a low 56Ni mass ( ) can reproduce the short plateau phase, as well as the sudden drop of the light curve, as observed in SN 2017czd. We conclude that SN 2017czd might be the first weak explosion identified from a SN IIb progenitor. We suggest that some rapidly evolving transients can be explained by such a weak progenitor explosion with a barely hydrogen-rich envelope.

Supernova 2017eaw: Molecule and Dust Formation from Infrared Observations

Abstract We present infrared (IR) photometry and spectroscopy of the Type II-P SN 2017eaw and its progenitor in the nearby galaxy NGC 6946. Progenitor observations in the Ks band in four epochs from 1 yr to 1 day before the explosion reveal no significant variability in the progenitor star greater than 6% that lasts longer than 200 days. SN 2017eaw is a typical SN II-P with near-IR and mid-IR photometric evolution similar to those of SNe 2002hh and 2004et, other normal SNe II-P in the same galaxy. Spectroscopic monitoring during the plateau phase reveals a possible high-velocity He i 1.083 μm absorption line, indicative of a shock interaction with the circumstellar medium. Spectra between 389 and 480 days postexplosion reveal a strong CO first overtone emission at 389 days, with a line profile matching that of SN 1987A from the same epoch, indicating ∼10−3 M ⊙ of CO at 1800 K. From the 389 days epoch until the most recent observation at 566 days, the first overtone feature fades while the 4.5 μm excess, likely from the CO fundamental band, remains. This behavior indicates that the CO has not been destroyed, but that the gas has cooled enough that the levels responsible for first overtone emissions are no longer populated. Finally, the evolution of Spitzer 3.6 μm photometry shows evidence for dust formation in SN 2017eaw, with a dust mass of 10−6 or 10−4 M ⊙ assuming carbonaceous or silicate grains, respectively.

Probing the final-stage progenitor evolution for Type IIP Supernova 2017eaw in NGC 6946

We presented a detailed analysis of progenitor properties of type IIP supernova 2017eaw in NGC 6946, based on the pre-explosion images and early-time observations obtained immediately after the explosion. An unusually red star, with M$_{F814W}$ = $-$6.9 mag and m$_{F606W}$$-$ m$_{F814W}=$2.9$\pm$0.2 mag, can be identified at the SN position in the pre-discovery Hubble Space Telescope(HST) images taken in 2016. The observed spectral energy distribution of this star, covering the wavelength of 0.6-2.0$\ \mathrm{\mu m}$, matches that of an M4-type red supergiant (RSG) with a temperature of about 3550 K. These results suggest that SN 2017eaw has a RSG progenitor with an initial mass of 12$\pm$2 M$_\odot$. The absolute F814W-band magnitude of this progenitor star is found to evolve from $-$7.2 mag in 2004 to $-$6.9 mag in 2016. Such a dimming effect is, however, unpredicted for a RSG in its neon/oxygen burning phase when its luminosity should modestly increase. The spectrum of SN 2017eaw taken a few hours after discovery clearly shows a narrow H$_\alpha$ emission feature blueshifted by $\sim$160 km s$^{-1}$. This narrow component disappeared in the spectrum taken two days later, suggesting the presence of a circumstellar material (CSM) shell (i.e., at a distance of $<$2.1-4.3$\times$10$^{14}$ cm). Combining the inferred distance with the expansion velocity of the CSM, we suggest that the progenitor of SN 2017eaw should have experienced violent mass loss at about 1-2 years prior to explosion, perhaps invoked by pulsational envelop ejection. This mechanism may help explain its luminosity decline in 2016 as well as the lack of detections of RSGs with initial mass in the range of 17 M$_\odot<$ M $<$ 25 M$_\odot$ as progenitors of SNe IIP.

A progenitor candidate for the type II-P supernova SN 2018aoq in NGC 4151

We present our findings based on pre- and post-explosion data of the type II-Plateau SN 2018aoq that exploded in NGC 4151. As distance estimates to NGC 4151 vary by an order of magnitude, we utilised the well-known correlation between ejecta velocity and plateau brightness, i.e. the standard candle method, to obtain a distance of 18.2 ± 1.2 Mpc, which is in very good agreement with measurements based on geometric methods. The above distance implies a mid-plateau absolute magnitude of MV50 = − 15.76 ± 0.14 suggesting that it is of intermediate brightness when compared to IIP SNe such as SN 2005cs at the faint end, and more typical events such as SN 1999em. This is further supported by relatively low expansion velocities (Fe IIλ5169 ∼ 3000 km s−1 at +42 d). Using archival HST/WFC3 imaging data, we find a point source coincident with the supernova position in the F350LP, F555W, F814W, and F160W filters. This source shows no significant variability over the ∼2 month time span of the data. From fits to the spectral energy distribution of the candidate progenitor, we find log(L/L⊙) ∼ 4.7 and Teff ∼ 3.5 kK, implying an M-type red supergiant progenitor. From comparisons to single and binary star models, we find that both favour the explosion of a star with a zero-age main sequence mass of ∼10 M⊙.

Bright Type IIP Supernovae in Low-metallicity Galaxies

Abstract We present measurements of the pseudo-equivalent width of the Fe ii λ5018 absorption feature in the spectra of 12 Type IIP supernovae (SNe II) in low-luminosity (M &gt; −17) dwarf host galaxies. The Fe ii λ5018 line has been called a useful diagnostic of the metallicity of the supernova (SN) progenitor stars. The events in our sample were discovered photometrically by the PanSTARRS Survey for Transients, and classified spectroscopically by us. Comparing our sample to 24 literature SNe II, we find that those in low-luminosity hosts have significantly weaker Fe ii features, with a probability of 10−4 that the two samples are drawn from the same distribution. Because low-mass galaxies are expected to contain a lower fraction of metals, our findings are consistent with a metallicity dependence for Fe ii λ5018, and therefore support the use of this line as a metallicity probe, in agreement with a number of recent works. In addition, we find that the SNe in faint (low-metallicity) hosts may be more luminous on average than those in the literature sample, suggesting possible physical differences between Type IIP SNe at low and high metallicity. However, accurate determinations of host galaxy extinction will be needed to quantify such an effect.

The surface abundances of red supergiants at core collapse

In the first weeks-to-months of a type II-P supernova (SN), the spectrum formation region is within the hydrogen-rich envelope of the exploding star. Optical spectra taken within a few days of the SN explosion, when the photosphere is hot, show features of ionised carbon, nitrogen and oxygen, as well as hydrogen and helium. Quantitative analysis of this very early phase may therefore constrain the chemical abundances of the stellar envelope at the point of core-collapse. Using existing and new evolutionary calculations for Red Supergiants (RSGs), we show that the predictions for the terminal surface [C/N] ratio is correlated with the initial mass of the progenitor star. Specifically, a star with an initial mass above 20M$_{\odot}$ exploding in the RSG phase should have an unequivocal signal of a low [C/N] abundance. Furthermore, we show that the model predictions are relatively insensitive to uncertainties in the treatment of convective mixing. Although there is a dependence on initial rotation, this can be dealt with in a probabilistic sense by convolving the model predictions with the observed distribution of stellar rotation rates. Using numerical experiments, we present a strategy for using very early-time spectroscopy to determine the upper limit to the progenitor mass distribution for type II-P SNe.

ASASSN-14dq: a fast-declining Type II-P supernova in a low-luminosity host galaxy

Optical broadband (UBVRI) photometric and low-resolution spectroscopic observations of the type II-P supernova (SN) ASASSN-14dq are presented. ASASSN-14dq exploded in a low-luminosity/metallicity host galaxy UGC 11860, the signatures of which are present as weak iron lines in the photospheric phase spectra. The SN has a plateau duration of $\sim\,$90 d, with a plateau decline rate of 1.38 $\rm mag\ (100 d)^{-1}$ in V-band which is higher than most type II-P SNe. ASASSN-14dq is a luminous type II-P SN with a peak $V$-band absolute magnitude of -17.7$\,\pm\,$0.2 mag. The light curve of ASASSN-14dq indicates it to be a fast-declining type II-P SN, making it a transitional event between the type II-P and II-L SNe. The empirical relation between the steepness parameter and $\rm ^{56}Ni$ mass for type II SNe was rebuilt with the help of well-sampled light curves from the literature. A $\rm ^{56}Ni$ mass of $\sim\,$0.029 M$_{\odot}$ was estimated for ASASSN-14dq, which is slightly lower than the expected $\rm ^{56}Ni$ mass for a luminous type II-P SN. Using analytical light curve modelling, a progenitor radius of $\rm \sim3.6\times10^{13}$ cm, an ejecta mass of $\rm \sim10\ M_{\odot}$ and a total energy of $\rm \sim\,1.8\times 10^{51}$ ergs was estimated for this event. The photospheric velocity evolution of ASASSN-14dq resembles a type II-P SN, but the Balmer features (H$\alpha$ and H$\beta$) show relatively slow velocity evolution. The high-velocity H$\alpha$ feature in the plateau phase, the asymmetric H$\alpha$ emission line profile in the nebular phase and the inferred outburst parameters indicate an interaction of the SN ejecta with the circumstellar material (CSM).

Multi-band Polarization of Type IIP Supernovae Due to Light Echo from Circumstellar Dust

Abstract Type IIP supernovae (SNe IIP) often show relatively high continuum polarization (∼1%) in the late phase. This polarization feature is generally believed to be due to an inner aspherical core revealed in the late phase, while this polarization feature can also be contributed by the effect of polarized-scattered echoes by circumstellar (CS) dust around the SN. In this paper, we propose a unique method to distinguish polarization from the SN ejecta and from the light echo. We quantitatively examine wavelength dependence of the polarization created by the scattered echoes for various geometries and amounts of CS dust. It is found that the polarization in the U-band has characteristic features, i.e., the polarization emerges at an earlier phase with higher polarization degree than that in longer wavelengths. These are due to the rapid evolution of the U-band light curve as well as higher optical depth of dust in shorter wavelengths. Except for the U band, the polarization increases after the plateau phase, and the polarization degree is generally higher for shorter wavelengths. These polarimetric features can be easily distinguished from the polarization expected from an aspherical core, which predicts almost no wavelength dependence. Moreover, we show that multi-band polarimetric observations for SNe IIP can constrain a parameter space in the CS dust mass and distance from the SNe. We thus encourage multi-band polarimetric observations for SNe IIP.

The Low-luminosity Type IIP Supernova 2016bkv with Early-phase Circumstellar Interaction

Abstract We present optical and near-infrared observations of a low-luminosity (LL) Type IIP supernova (SN) 2016bkv from the initial rising phase to the plateau phase. Our observations show that the end of the plateau is extended to ≳140 days since the explosion, indicating that this SN takes one of the longest times to finish the plateau phase among Type IIP SNe (SNe IIP), including LL SNe IIP. The line velocities of various ions at the middle of the plateau phase are as low as 1000–1500 km s−1, which is the lowest even among LL SNe IIP. These measurements imply that the ejecta mass in SN 2016bkv is larger than that of the well-studied LL IIP SN 2003Z. In the early phase, SN 2016bkv shows a strong bump in the light curve. In addition, the optical spectra in this bump phase exhibit a blue continuum accompanied by a narrow Hα emission line. These features indicate an interaction between the SN ejecta and the circumstellar matter (CSM) as in SNe IIn. Assuming the ejecta–CSM interaction scenario, the mass loss rate is estimated to be yr−1 within a few years before the SN explosion. This is comparable to or even larger than the largest mass loss rate observed for the Galactic red supergiants ( yr−1 for VY CMa). We suggest that the progenitor star of SN 2016bkv experienced a violent mass loss just before the SN explosion.

SNe 2013K and 2013am: observed and physical properties of two slow, normal Type IIP events

We present 1 yr of optical and near-infrared photometry and spectroscopy of the Type IIP SNe 2013K and 2013am. Both objects are affected by significant extinction, due to their location in dusty regions of their respective host galaxies, ESO 009-10 and NGC 3623 (M65). From the photospheric to nebular phases, these objects display spectra congruent with those of underluminous Type IIP SNe (i.e. the archetypal SNe 1997D or 2005cs), showing low photospheric velocities (∼2 × 103 km s−1 at 50 d) together with features arising from Ba ii that are particularly prominent in faint SNe IIP. The peak V-band magnitudes of SN 2013K (−15.6 mag) and SN 2013am (−16.2 mag) are fainter than standard-luminosity Type IIP SNe. The ejected nickel masses are 0.012 ± 0.010 and 0.015 ± 0.006 M⊙ for SN 2013K and SN 2013am, respectively. The physical properties of the progenitors at the time of explosion are derived through hydrodynamical modelling. Fitting the bolometric curves, the expansion velocity and the temperature evolution, we infer total ejected masses of 12 and 11.5 M⊙, pre-SN radii of ∼460 and ∼360 R⊙, and explosion energies of 0.34 foe and 0.40 foe for SN 2013K and SN 2013am. Late time spectra are used to estimate the progenitor masses from the strength of nebular emission lines, which turn out to be consistent with red supergiant progenitors of ∼15 M⊙. For both SNe, a low-energy explosion of a moderate-mass red supergiant star is therefore the favoured scenario.

Emission line models for the lowest mass core-collapse supernovae – I. Case study of a 9 M⊙ one-dimensional neutrino-driven explosion

A large fraction of core-collapse supernovae (CCSNe), 30-50%, are expected to originate from the low-mass end of progenitors with $M_{\rm ZAMS}~= 8-12~M_\odot$. However, degeneracy effects make stellar evolution modelling of such stars challenging, and few predictions for their supernova light curves and spectra have been presented. Here we calculate synthetic nebular spectra of a 9 $M_\odot$ Fe CCSN model exploded with the neutrino mechanism. The model predicts emission lines with FWHM$\sim$1000 km/s, including signatures from each deep layer in the metal core. We compare this model to observations of the three subluminous IIP SNe with published nebular spectra; SN 1997D, SN 2005cs, and SN 2008bk. The prediction of both line profiles and luminosities are in good agreement with SN 1997D and SN 2008bk. The close fit of a model with no tuning parameters provides strong evidence for an association of these objects with low-mass Fe CCSNe. For SN 2005cs, the interpretation is less clear, as the observational coverage ended before key diagnostic lines from the core had emerged. We perform a parameterised study of the amount of explosively made stable nickel, and find that none of these three SNe show the high $^{58}$Ni/$^{56}$Ni ratio predicted by current models of electron capture SNe (ECSNe) and ECSN-like explosions. Combined with clear detection of lines from O and He shell material, these SNe rather originate from Fe core progenitors. We argue that the outcome of self-consistent explosion simulations of low-mass stars, which gives fits to many key observables, strongly suggests that the class of subluminous Type IIP SNe is the observational counterpart of the lowest mass CCSNe.

Circumstellar Light Echo as a Possible Origin of the Polarization of Type IIP Supernovae

Abstract Type IIP supernovae (SNe IIP) are the most common class of core-collapse SNe. They often show a rapid increase of polarization degree in the late phase. This time evolution is generally believed to originate from the emergence of an inner aspherical core, while the effect of polarized-scattered echoes by circumstellar (CS) dust around the SN may also substantially contribute to this polarization feature. In this study, we examine the effects of the scattered echoes on the SN polarization through radiative transfer simulations for various geometries and amounts of CS dust. It is found that asymmetrically distributed CS dust, which is generally inferred for red supergiants, can reproduce the observed polarization features. We have applied our results to SNe 2004dj and 2006ov, deriving the geometry and amount of CS dust to explain their observed polarization features in this scenario. For both SNe, the blob-like or bipolar distribution of CS dust rather than the disk-like distribution is favored. The derived dust masses in the blob model (the bipolar CS dust model) for SNe 2004dj and 2006ov are ( ) and ( ), respectively. Even in the case where this process would not play a dominant role in the observed polarization signals, this effect should in principle contribute to it, the strength of which depends on the nature of the CS dust. Therefore, this effect must be taken into account in discussing the multi-dimensional structure of an SN explosion through polarimetric observations.

Progenitors of low-luminosity Type II-Plateau supernovae

The progenitors of low-luminosity Type II-Plateau supernovae (SNe II-P) are believed to be red supergiant (RSG) stars, but there is much disparity in the literature concerning their mass at core collapse and therefore on the main sequence. Here, we model the SN radiation arising from the low-energy explosion of RSG stars of 12, 25, and 27 M$_{\odot}$ on the main sequence and formed through single star evolution. Despite the narrow range in ejecta kinetic energy (2.5$-$4.2$\times$10$^{50}$ erg) in our model set, the SN observables from our three models are significantly distinct, reflecting the differences in progenitor structure (e.g., surface radius, H-rich envelope mass, He-core mass). Our higher mass RSG stars give rise to Type II SNe that tend to have bluer colors at early times, a shorter photospheric phase, and a faster declining $V$-band light curve (LC) more typical of Type II-linear SNe, in conflict with the LC plateau observed for low-luminosity SNe II. The complete fallback of the CO core in the low-energy explosions of our high mass RSG stars prevents the ejection of any ${}^{56}$Ni (nor any core O or Si), in contrast to low-luminosity SNe II-P, which eject at least 0.001 M$_{\odot}$ of ${}^{56}$Ni. In contrast to observations, type II SN models from higher mass RSGs tend to show an H$\alpha$ absorption that remains broad at late times (due to a larger velocity at the base of the H-rich envelope). In agreement with the analyses of pre-explosion photometry, we conclude that low-luminosity SNe II-P likely arise from low-mass rather than high-mass RSG stars.

Light-curve Analysis of Ordinary Type IIP Supernovae Based on Neutrino-driven Explosion Simulations in Three Dimensions

Abstract Type II-plateau supernovae (SNe IIP) are the most numerous subclass of core-collapse SNe originating from massive stars. In the framework of the neutrino-driven explosion mechanism, we study the properties of the SN outburst for a red supergiant progenitor model and compare the corresponding light curves with observations of the ordinary Type IIP SN 1999em. Three-dimensional (3D) simulations of (parametrically triggered) neutrino-driven explosions are performed with the (explicit, finite-volume, Eulerian, multifluid hydrodynamics) code Prometheus, using a presupernova model of a 15 M ⊙ star as initial data. On approaching homologous expansion, the hydrodynamic and composition variables of the 3D models are mapped to a spherically symmetric configuration, and the simulations are continued with the (implicit, Lagrangian, radiation hydrodynamics) code Crab to follow the evolution of the blast wave during the SN outburst. Our 3D neutrino-driven explosion model with an explosion energy of about erg produces 56Ni in rough agreement with the amount deduced from fitting the radioactively powered light-curve tail of SN 1999em. The considered presupernova model, 3D explosion simulations, and light-curve calculations can explain the basic observational features of SN 1999em, except for those connected to the presupernova structure of the outer stellar layers. Our 3D simulations show that the distribution of 56Ni-rich matter in velocity space is asymmetric with a strong dipole component that is consistent with the observations of SN 1999em. The monotonic decline in luminosity from the plateau to the radioactive tail in ordinary SNe IIP is a manifestation of the intense turbulent mixing at the He/H composition interface.

Radii and Mass-loss Rates of Type IIb Supernova Progenitors

Abstract Several Type IIb supernovae (SNe IIb) have been extensively studied, both in terms of the progenitor radius and the mass-loss rate in the final centuries before the explosion. While the sample is still limited, evidence has been accumulating that the final mass-loss rate tends to be larger for a more extended progenitor, with the difference exceeding an order of magnitude between the more and less extended progenitors. The high mass-loss rates inferred for the more extended progenitors are not readily explained by a prescription commonly used for a single stellar wind. In this paper, we calculate a grid of binary evolution models. We show that the observational relation in the progenitor radii and mass-loss rates may be a consequence of non-conservative mass transfer in the final phase of progenitor evolution without fine tuning. Further, we find a possible link between SNe IIb and SNe IIn. The binary scenario for SNe IIb inevitably leads to a population of SN progenitors surrounded by dense circumstellar matter (CSM) due to extensive mass loss ( ) in the binary origin. About 4% of all observed SNe IIn are predicted to have dense CSM, produced by binary non-conservative mass transfer, whose observed characteristics are distinguishable from SNe IIn from other scenarios. Indeed, such SNe may be observationally dominated by systems experiencing huge mass loss in the final 103 yr, leading to luminous SNe IIn or initially bright SNe IIP or IIL with characteristics of SNe IIn in their early spectra.

The resolved stellar populations around 12 Type IIP supernovae

Core-collapse supernovae are found in regions associated with recent massive star formation. The stellar population observed around the location of a SN can be used as a probe of the origins of the progenitor star. We apply a Bayesian mixture model to fit isochrones to the massive star population around twelve Type IIP SNe, for which constraints on the progenitors are also available from fortuitous pre-explosion images. Using the high-resolution Hubble Space Telescope Advanced Camera for Surveys and Wide Field Camera 3, we study the massive star population found within 100pc of each our target SNe. For most of the SNe in our sample, we find that there are multiple age components in the surrounding stellar populations. In the cases of SNe~2003gd and 2005cs, we find that the progenitor does not come from the youngest stellar population component and, in fact, these relatively low mass progenitors ($\sim 8M_{\odot}$) are found in close proximity to stars as massive as $15$ and $50-60M_{\odot}$, respectively. Overall, the field extinction (Galactic and host) derived for these populations is $\sim 0.3\,\mathrm{mags}$ higher than the extinction that was generally applied in previously reported progenitor analyses. We also find evidence, in particular for SN~2004dj, for significant levels of differential extinction. Our analysis for SN~2008bk suggests a significantly lower extinction for the population than the progenitor, but the lifetime of the population and mass determined from pre-explosion images agree. Overall, assuming that the appropriate age component can be suitably identified from the multiple stellar population components present, we find that our Bayesian approach to studying resolved stellar populations can match progenitor masses determined from direct imaging to within $\pm 3M_{\odot}$.