Using a parametric approach, we determine the configuration of super-AGB stars at the explosion as a function of the initial mass and metallicity, in order to verify if the EC-SN scenario involving a super-AGB star is compatible with the observations regarding SN2008ha and SN2008S. The results show that both the SNe can be explained in terms of EC-SNe from super-AGB progenitors having a different configuration at the collapse. The impact of these results on the interpretation of other sub-luminous SNe is also discussed.
We investigate the thermal response of CO WDs accreting He-rich matter directly from their companions in binary systems. Our results suggest that the He-channel cannot provide progenitors for majority of "normal" SNe Ia.
Symbiotic stars are interacting binaries in which the first-formed white dwarf accretes and burns material from a red giant companion. This paper aims at presenting physical characteristics of these objects and discussing their possible link with progenitors of type Ia supernovae.
We have performed detailed high-resolution spectroscopic analysis on seven metal-poor stars (BD+75 348, BD+09 3019, HD238020, HE0319-0215, HE0507-1653, HE0930-0018, HE1023-1504) and derived their atmospheric parameters T$_{eff}$, log$g$, [Fe/H], and mictroturbulent velocity ($ξ$). The metallicity range is found to be -2.57$<$[Fe/H]$<$-0.42. The elemental abundances of 17 light elements and 12 heavy elements are estimated. We have classified BD+75 348 and BD+09 3019 as strong Ba stars, HD238020 as a mild Ba star, and the remaining four objects as CEMP-s stars. We have estimated the masses of th…
The hybrid CONe white dwarfs (WDs) have been suggested to be possible progenitors of type Ia supernovae (SNe Ia). In this article, we systematically studied the hybrid CONe WD + He star scenario for the progenitors of SNe Ia, in which a hybrid CONe WD increases its mass to the Chandrasekhar mass limit by accreting He-rich material from a non-degenerate He star. According to a series of detailed binary population synthesis simulations, we obtained the SN Ia birthrates and delay times for this scenario. The SN Ia birthrates for this scenario are ~0.033-0.539*10^(-3)yr^(-1), which roughly account…
The origin of dust in a galaxy is poorly understood. Recently, the surveys of the Large Magellanic Cloud (LMC) provide astrophysical laboratories for the dust studies. By a method of population synthesis, we investigate the contributions of dust produced by asymptotic giant branch (AGB) stars, common envelope (CE) ejecta and type II supernovae (SNe II) to the total dust budget in the LMC. Based on our models, the dust production rates (DPRs) of AGB stars in the LMC are between about $2.5\times10^{-5}$ and $4.0\times10^{-6}M_\odot{\rm yr^{-1}}$. The uncertainty mainly results from different mod…
SNe Iax are proposed as one new sub-class of SNe Ia. SNe Iax have been estimated to account for ~5-30% of the total SN Ia rate, and most SNe Iax have been discovered in late-type galaxies. In addition, observations constrain the progenitor systems of some SN Iax progenitors have ages of <80Myr. Recently, the weak deflagration explosions of Ch-mass CO WDs seem to provide a viable physical scenario for SNe Iax. Here, comparing theoretical predictions from BPS calculations with SN Iax observations, we put constraints on the SD Ch-mass model as a possible Iax progenitor. A long delay times of >3Gy…
We estimate the total dust input from the cool evolved stars in the Small Magellanic Cloud (SMC), using the 8 micron excess emission as a proxy for the dust-production rate. We find that Asymptotic Giant Branch (AGB) and red supergiant (RSG) stars produce (8.6-9.5) x 10^7 solar masses per year of dust, depending on the fraction of far-infrared sources that belong to the evolved star population (with 10%-50% uncertainty in individual dust-production rates). RSGs contribute the least (<4%), while carbon-rich AGB stars (especially the so-called "extreme" AGB stars) account for 87%-89% of the tota…
We study the effects of neutron captures in AGB stars on \oq Fe-group\cqb elements, with an emphasis on Cr, Fe, and Ni. These elements show anomalies in $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni in solar-system materials, which are commonly attributed to SNe. However, as large fractions of the interstellar medium (ISM) were reprocessed in AGB stars, these elements were reprocessed, too. We calculate the effects of such reprocessing on Cr, Fe, and Ni through 1.5\msb and 3\msb AGB models, adopting solar and 1/3 solar metallicities. All cases produce excesses of $^{54}$Cr, $^{58}$Fe, and $^{64}$Ni, whi…
We review the lives, deaths and nucleosynthetic signatures of intermediate mass stars in the range approximately 6.5-12 Msun, which form super-AGB stars near the end of their lives. We examine the critical mass boundaries both between different types of massive white dwarfs (CO, CO-Ne, ONe) and between white dwarfs and supernovae and discuss the relative fraction of super-AGB stars that end life as either an ONe white dwarf or as a neutron star (or an ONeFe white dwarf), after undergoing an electron capture supernova. We also discuss the contribution of the other potential single-star channels…
Luminous blue variable (LBV) stars are very massive, luminous, unstable stars that suffer frequent eruptions. In the last few years, these stars have been proposed as the direct progenitors of some core-collapse supernovae (SNe), particularly Type IIn SNe, in conflict with stellar evolution theory. In this paper we investigate various scenarios wherein LBV stars have been suggested as the immediate progenitors of SNe. Many of these suggestions stem from the fact that the SNe appear to be expanding in a high density medium, which has been interpreted as resulting from a wind with a high mass-lo…
We show the initial and final parameter space for SNe Ia in a ($\log P^{\rm i}, M_{\rm 2}^{\rm i}$) plane and find that the positions of some famous recurrent novae, as well as a supersoft X-ray source (SSS), RX J0513.9-6951, are well explained by our model. The model can also explain the space velocity and mass of Tycho G, which is now suggested to be the companion star of Tycho's supernova. Our study indicates that the SSS, V Sge, might be the potential progenitor of supernovae like SN 2002ic if the delayed dynamical-instability model due to Han & Podsiadlowski (2006) is appropriate. Followi…
Origin of enhanced abundance of heavy elements observed in the surface chemical composition of carbon-enhanced metal-poor (CEMP) stars still remain poorly understood. Here, we present detailed abundance analysis of seven CEMP stars based on high resolution (R${\sim}$ 50\,000) spectra that reveal enough evidence of Asymptotic Giant Branch (AGB) stars being possible progenitors for these objects. For the objects HE0110$-$0406, HE1425$-$2052 and HE1428$-$1950, we present for the first time a detailed abundance analysis. Our sample is found to consists of one metal-poor ([Fe/H]$<$$-1.0$) and six v…
Type IIb supernovae (SNe) present a unique opportunity for understanding the progenitors of stripped-envelope (SE) SNe as the stellar progenitor of several Type IIb SNe have been identified in pre-explosion images. In this paper, we use Bayesian inference and a large grid of non-rotating solar-metallicity single and binary stellar models to derive the associated probability distributions of single and binary progenitors of the Type IIb SN 2016gkg using existing observational constraints. We find that potential binary star progenitors have smaller pre-SN hydrogen-envelope and helium-core masses…
Incorporating the effect of mass-stripping and accretion-disk instability on the evolution of WD binary, we carried out binary stellar evolution calculations for more than 1600 close WD binaries. As a result, the initial parameter spaces for SNe Ia are presented in an orbital period-secondary mass ($\log P_{\rm i}, M_{\rm 2}^{\rm i}$) plane. We confirmed that in a WD + MS system, the initial companion leading to SNe Ia may have mass from 1 $M_{\odot}$ to 5 $M_{\odot}$. The initial WD mass for SNe Ia from WD + MS channel is as low as 0.565 $M_{\odot}$, while the lowest WD mass from the WD + RG …
Type Ia supernovae (SNe Ia) play an important role in astrophysics and are crucial for the studies of stellar evolution, galaxy evolution and cosmology. They are generally thought to be thermonuclear explosions of accreting carbon-oxygen white dwarfs (CO WDs) in close binaries, however, the nature of the mass donor star is still unclear. In this article, we review various progenitor models proposed in the past years and summarize many observational results that can be used to put constraints on the nature of their progenitors. We also discuss the origin of SN Ia diversity and the impacts of SN…
Abridged: Getting a better understanding of the evolution and nucleosynthetic yields of the most metal-poor stars (appr. Z<=10^-5) is critical because they are part of the big picture of the history of the primitive Universe. Yet many of the remaining unknowns of stellar evolution lie in the birth, life, and death of these objects. We review stellar evolution of intermediate-mass (IMS) Z<=10-5 models existing in the literature, with a focus on the problem of their final fates. The depth and efficiency of mixing episodes are critical to determine the mass limits for the formation of electron-ca…
Type Ia supernovae (SNe Ia) play an important role in the study of cosmic evolution, especially in cosmology. There are several progenitor models for SNe Ia proposed in the past years. In this paper, by considering the effect of accretion disk instability on the evolution of white dwarf (WD) binaries, we performed detailed binary evolution calculations for the WD + red-giant (RG) channel of SNe Ia, in which a carbon-oxygen WD accretes material from a RG star to increase its mass to the Chandrasekhar mass limit. According to these calculations, we mapped out the initial and final parameters for…
Type Iax supernovae (SNe Iax) are proposed as one new sub-class of SNe Ia since they present observational properties that are sufficiently distinct from the bulk of SNe Ia. SNe Iax are the most common of all types of peculiar SNe by both number and rate, with an estimated rate of occurrence of about 5-30% of the total SN Ia rate. However, the progenitor systems of SNe Iax are still uncertain. Analyzing pre-explosion images at SN Iax positions provides a direct way to place strong constraints on the nature of progenitor systems of SNe Iax. In this work, we predict pre-explosion properties of b…
I propose that some irregular `messy' planetary nebulae owe their morphologies to triple-stellar evolution where tight binary systems evolve inside and/or on the outskirts the envelope of asymptotic giant branch (AGB) stars. In some cases the tight binary system can survive, in other it is destroyed. The tight binary system might breakup with one star leaving the system. In an alternative evolution, one of the stars of the brook-up tight binary system falls toward the AGB envelope with low specific angular momentum, and drowns in the envelope. In a different type of destruction process the dra…
The acquisition of late-time imaging is an important step in the analysis of pre-explosion observations of the progenitors of supernovae. We present late-time HST ACS WFC observations of the sites of five Type IIP SNe: 1999ev, 2003gd, 2004A, 2005cs and 2006my. Observations were conducted using the F435W, F555W and F814W filters. We confirm the progenitor identifications for SNe 2003gd, 2004A and 2005cs, through their disappearance. We find that a source previously excluded as being the progenitor of SN 2006my has now disappeared. The late-time observations of the site of SN 1999ev cast signifi…
We conduct a population synthesis study of the common envelope evolution (CEE) of a white dwarf (WD) and an asymptotic giant branch (AGB) star and find that the potential number of type Ia supernovae (SNe Ia) from the core degenerate (CD) and from the double degenerate (DD) scenarios are of the same order of magnitude. For the CD scenario we consider cases where a carbon oxygen rich (CO) AGB core and a CO WD merge during the CEE and leave a WD remnant with a mass of >1.35Mo, and for the DD scenario we count surviving CO WD binary systems that merge within a time of 10 Gyr. When either the AGB …
After off-center C ignition in the cores of super-AGB stars the C flame propagates all the way down to the center, trailing behind it the C-shell convective zone, and thus building a degenerate ONe core. This standard picture is obtained in stellar evolution simulations if the bottom C-shell convection boundary is assumed to be a discontinuity associated with a strict interpretation of the Schwarzschild condition for convective instability. However, this boundary is prone to additional mixing processes, such as thermohaline convection and convective boundary mixing. Using hydrodynamic simulati…
In the single degenerate (SD) scenario for type Ia supernovae (SNe Ia), a mass-accreting white dwarf is expected to experience a supersoft X-ray source (SSS) phase. However, some recent observations showed that the expected number of the mass-accreting WD is much lower than that predicted from theory, whatever in spiral or elliptical galaxies. In this paper, we did a binary population synthesis study on the relative duration of the SSS phase to their whole mass-increasing phase of WDs leading to SNe Ia. We found that for about 40% progenitor systems, the relative duration is shorter than 2% an…
We present comprehensive photometric and spectroscopic observations of the faint transient SN 2008S discovered in NGC 6946. SN 2008S exhibited slow photometric evolution and almost no spectral variability during the first nine months, implying a high density CS medium. The light curve is similar in shape to that of SN 1998S and SN 1979C, although significantly fainter at maximum light. Our quasi-bolometric lightcurve extends to 300 days and shows a tail phase decay rate consistent with that of ^{56}Co. We propose that this is evidence for an explosion and formation of ^{56}Ni (0.0015 +/- 0.000…
The discovery of the accelerated expansion of the universe using Type Ia supernovae (SNe Ia) has stimulated a tremendous amount of interest in the use of SNe Type Ia events as standard cosmological candles, and as a probe of the fundamental physics of dark energy. Recent observations of SNe Ia have indicated a significant population difference depending on the host galaxy. These observational findings are consistent with SNe Ia Ni-56 production in star-forming spiral galaxies some 0.1 solar masses higher - and therefore more luminous than in elliptical galaxies. We present recent full-star, 3D…
It has recently been proposed that one sub-class of type Ia supernovae (SNe Ia) is sufficiently both distinct and common to be classified separately from the bulk of SNe Ia, with a suggested class name of "type Iax supernovae" (SNe Iax), after SN 2002cx. We show that the population properties of this class can be understood if the events originate from helium double-detonation sub-Chandrasekhar mass explosions, in which a carbon--oxygen white dwarf (CO WD) accumulates a helium layer from a non-degenerate helium star. We have incorporated detailed binary evolution calculations for the progenito…
Type Ia supernovae (SNe Ia) are thermonuclear explosions of carbon-oxygen white dwarfs (WDs) that accrete mass from a binary companion, which can be either a non-degenerate star (a main-sequence star or a giant) or an other WD in a binary merger (single- and double-degenerate scenario, respectively). In population-synthesis studies of SNe Ia the contribution of asymptotic giant branch (AGB) stars to either scenario is marginal. However, most of these studies adopt simplified assumptions to compute the effects of wind mass loss and accretion in binary systems. This work investigates the impact …
We present narrow-, broad-band, and WISE archive images, and high- and intermediate-resolution long-slit spectra of K 4-37, a planetary nebula that has never been analyzed in detail. Although K 4-37 appears bipolar, the morphokinematical analysis discloses the existence of three distinct axes and additional particular directions in the object, indicating that K 4-37 is a multi-axis planetary nebula that has probably been shaped by several bipolar outflows at different directions. A 4-6 M$_{\odot}$ main-sequence progenitor is estimated from the derived high nebular He and N abundances, and very…
We discuss the properties of the progenitors of core collapse SNe, as they can be deduced from rotating stellar models of single stars. The type of the SN progenitor was determined from the surface abundances at the pre-SN stage. The type of the SN event was obtained from the masses of hydrogen and helium ejected at the time of the core-collapse SN event. We find that the minimum amount of helium ejected by a core-collapse SN (of whatever type) is around 0.3 MSun. There is no difference between the WC and WO stars in the ejected masses of helium, CNO elements, and heavy elements. Also no diffe…
The most massive stars on the asymptotic giant branch (AGB), so called super-AGB stars, are thought to produce supernovae (SNe) triggered by electron captures in their degenerate O+Ne+Mg cores. Super-AGB stars are expected to have slow winds with high mass-loss rates, so their wind density is high. The explosions of super-AGB stars are therefore presumed to occur in this dense wind. We provide the first synthetic light curves (LCs) for such events by exploding realistic electron-capture supernova (ecSN) progenitors within their super-AGB winds. We find that the early LC, i.e. before the recomb…
The bolometric properties (nickel mass, ejecta mass and kinetic energies) of 61 Ibc supernovae (SNe), including 20 Gamma-Ray Burst and X-Ray Flash (GRB/XRF), 19 Ib, 13 Ic and 9 Ic-BL (broad-lined) SNe are presented. All of the available $BVRI$ photometry in the literature have been collected and used in a new method that utilizes a template supernova (SN 1998bw) and an analytical model based on Arnett (1982) to accurately estimate the bolometric properties of each SN. A statistical analysis of the bolometric properties is then performed, where it is found that GRB/XRF SNe are the most energeti…
Type Iax supernovae (SNe~Iax) are the most common class of peculiar SNe. While they are thought to be thermonuclear white-dwarf (WD) SNe, SNe~Iax are observationally similar to, but distinct from SNe~Ia. Unlike SNe~Ia, where roughly 30\% occur in early-type galaxies, only one SN~Iax has been discovered in an early-type galaxy, suggesting a relatively short delay time and a distinct progenitor system. Furthermore, one SN~Iax progenitor system has been detected in pre-explosion images with its properties consistent with either of two models: a short-lived (<100 Myr) progenitor system consisting …
We study the chemical abundances of a wide sample of 142 Galactic planetary nebulae (PNe) with good quality observations, for which the abundances have been derived more or less homogeneously, thus allowing a reasonable comparison with stellar models. The goal is the determination of mass, chemical composition and formation epoch of their progenitors, through comparison of the data with results from AGB evolution. The dust properties of PNe, when available, were also used to further support our interpretation. We find that the majority ($\sim60\%$) of the Galactic PNe studied has nearly solar …
Context: The nature of type Ia supernovae (SNe Ia) is still unclear. Metallicities may have an important effect on their properties. Aims: In this paper, we study the He star donor channel towards SNe Ia comprehensively and systematically at various metallicities. Methods: Employing Eggleton's stellar evolution code with the optically thick wind assumption, we calculated about 10 000 WD + He star systems and obtained SN Ia production regions of the He star donor channel with metallicities Z=0.03, 0.02, 0.004 and 0.0001. According to a detailed binary population synthesis approach, we also obta…
The core-degenerate (CD) scenario has been suggested to be a possible progenitor model of type Ia supernovae (SNe Ia), in which a carbon-oxygen white dwarf (CO WD) merges with the hot CO core of a massive asymptotic giant branch (AGB) star during their common-envelope phase. However, the SN Ia birthrates for this scenario are still uncertain. We conducted a detailed investigation into the CD scenario and then gave the birthrates for this scenario using a detailed Monte Carlo binary population synthesis approach. We found that the delay times of SNe Ia from this scenario are ~70Myrs-1400Myrs, w…
Using the largest spectroscopic dataset of stripped-envelope core-collapse supernovae (stripped SNe), we present a systematic investigation of spectral properties of Type IIb SNe (SNe IIb), Type Ib SNe (SNe Ib), and Type Ic SNe (SNe Ic). Prior studies have been based on individual objects or small samples. Here, we analyze 227 spectra of 14 SNe IIb, 258 spectra of 21 SNe Ib, and 207 spectra of 17 SNe Ic based on the stripped SN dataset of Modjaz et al. (2014) and other published spectra of individual SNe. Each SN in our sample has a secure spectroscopic ID, a date of $V$-band maximum light, an…
There are a growing number of nearby SNe for which the progenitor star is detected in archival pre-explosion imaging. From these images it is possible to measure the progenitor's brightness a few years before explosion, and ultimately estimate its initial mass. Previous work has shown that II-P and II-L supernovae (SNe) have Red Supergiant (RSG) progenitors, and that the range of initial masses for these progenitors seems to be limited to $<$17M$_\odot$. This is in contrast with the cutoff of 25-30M$_\odot$ predicted by evolutionary models, a result which is termed the 'Red Supergiant Problem'…
Using resolved stellar photometry measured from archival HST imaging, we generate color-magnitude diagrams of the stars within 50 pc of the locations of historic core-collapse supernovae that took place in galaxies within 8 Mpc. We fit these color-magnitude distributions with stellar evolution models to determine the best-fit age distribution of the young population. We then translate these age distributions into probability distributions for the progenitor mass of each SNe. The measurements are anchored by the main-sequence stars surrounding the event, making them less sensitive to assumption…
Two "twin" Type Ia supernovae (SNe Ia), SNe 2011by and 2011fe, have extremely similar optical light-curve shapes, colors, and spectra, yet have different ultraviolet (UV) continua as measured in Hubble Space Telescope spectra and measurably different peak luminosities. We attribute the difference in the UV continua to significantly different progenitor metallicities. This is the first robust detection of different metallicities for SN Ia progenitors. Theoretical reasoning suggests that differences in metallicity also lead to differences in luminosity. SNe Ia with higher progenitor metallicitie…
We calculate the expected number of type Ia supernovae (SN Ia) in the core-degenerate (CD) scenario and find it to match observations within the uncertainties of the code. In the CD scenario the super-Chandrasekhar mass white dwarf (WD) is formed at the termination of the common envelope phase from a merger of a WD companion with the hot core of a massive asymptotic giant branch (AGB) star. We use a simple population synthesis code that avoids the large uncertainties involved in estimating the final orbital separation of the common envelope evolution. Instead, we assume that systems where the …
High-quality collections of Type II supernova (SN) light curves are scarce because they evolve for hundreds of days, making follow-up observations time consuming and often extending over multiple observing seasons. In light of these difficulties, the diversity of SNe II is not fully understood. Here we present ultraviolet and optical photometry of 12 SNe II monitored by the Las Cumbres Observatory Global Telescope Network (LCOGT) during 2013-2014, and compare them with previously studied SNe having well-sampled light curves. We explore SN II diversity by searching for correlations between the …
We present a comprehensive abundance analysis of two newly-discovered carbon-enhanced metal-poor (CEMP) stars. HE2138-3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if NLTE corrections are included ([Pb/Fe] = +3.84). HE2258-6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R ~ 2,000) spectroscopy with GEMINI/GMOS. We report here on derived abu…
The most favored progenitor scenarios for Type Ia supernovae (SNe Ia) involve the single-degenerate (SD) scenario and the double-degenerate scenario. The absence of stripped hydrogen (H) in the nebular spectra of SNe Ia challenges the SD progenitor models. Recently, it was shown that pure deflagration explosion models of Chandrasekhar-mass white dwarfs ignited off-center reproduce the characteristic observational features of 2002cx-like SNe Ia very well. In this work we predict, for the first time, the amount of stripped H for the off-center pure deflagration explosions. We find that their low…
Type IIn Supernovae (SNe IIn) are rare events, constituting only a few percent of all core-collapse SNe, and the current sample of well observed SNe IIn is small. Here, we study the four SNe IIn observed by the Caltech Core-Collapse Project (CCCP). The CCCP SN sample is unbiased to the extent that object selection was not influenced by target SN properties. Therefore, these events are representative of the observed population of SNe IIn. We find that a narrow P-Cygni profile in the hydrogen Balmer lines appears to be a ubiquitous feature of SNe IIn. Our light curves show a relatively long rise…
The Galactic population of close white dwarf binaries is expected to provide the largest number of gravitational wave sources for low frequency detectors such as the Laser Interferometer Space Antenna (LISA). Current data analysis techniques have demonstrated the capability of resolving on the order of $10^4$ white dwarf binaries from a 2 year observation. Resolved binaries are either at high frequencies or large amplitudes. Such systems are more likely to be high-mass binaries, a subset of which will be progenitors of SNe Ia in the double degenerate scenario. We report on results of a study o…
Comparing the ejecta velocities at maximum brightness and narrow circumstellar/interstellar Na D absorption line profiles of a sample of 23 Type Ia supernovae (SNe Ia), we determine that the properties of SN Ia progenitor systems and explosions are intimately connected. As demonstrated by Sternberg et al. (2011), half of all SNe Ia with detectable Na D absorption at the host-galaxy redshift in high-resolution spectroscopy have Na D line profiles with significant blueshifted absorption relative to the strongest absorption component, which indicates that a large fraction of SN Ia progenitor syst…
I study the possibility that within the frame of the core degenerate (CD) scenario for type Ia supernovae (SNe Ia) the merger process of the core of the asymptotic giant branch (AGB) star and the white dwarf (WD) maintains an envelope mass of ~0.03Mo that causes a later helium shell flash. I estimate the number of pre-explosion helium shell flash events to be less than few per cents of all CD scenario SNe Ia. A helium shell flash while the star moves to the left on the HR diagram as a post-AGB star (late thermal pulse; LTP) or along the WD cooling track (very LTP) causes the star to expand and…
The origin of the progenitors of type Ia supernovae (SNe Ia) is still uncertain. The core-degenerate (CD) scenario has been proposed as an alternative way for the production of SNe Ia. In this scenario, SNe Ia are formed at the final stage of common-envelope evolution from a merger of a carbon-oxygen white dwarf (CO WD) with the CO core of an asymptotic giant branch companion. However, the birthrates of SNe Ia from this scenario are still not well determined. In this work, we performed a detailed investigation on the CD scenario based on a binary population synthesis approach. The SN Ia delay …
Type IIb supernovae (SNe) are important candidates to understand mechanisms that drive the stripping of stripped-envelope (SE) supernova (SN) progenitors. While binary interactions and their high incidence are generally cited to favor them as Type IIb SN progenitors, this idea has not been tested using models covering a broad parameter space. In this paper, we use non-rotating single- and binary-star models at solar and low metallicities spanning a wide parameter space in primary mass, mass ratio, orbital period, and mass transfer efficiencies. We find that our single- and binary-star models c…
We investigate the effect of mixing of radioactive nickel ($^{56}$Ni) on the early-time color evolution of Type Ib and Ic supernovae (SNe Ib/Ic) using multi-group radiation hydrodynamics simulations. We consider both helium-rich and helium-poor progenitors. Mixing of $^{56}$Ni is parameterized using a Gaussian distribution function. We find that the early-time color evolution with a weak $^{56}$Ni mixing is characterized by three different phases: initial rapid reddening, blueward evolution due to the delayed effect of $^{56}$Ni heating, and redward evolution thereafter until the transition to…
We present direct spectroscopic modeling of 44 Type Iax supernovae (SNe Iax) using spectral synthesis code SYNAPPS. We confirm detections of helium emission in the early-time spectra of two SNe Iax: SNe 2004cs and 2007J. These He I features are better fit by a pure-emission Gaussian than by a P-Cygni profile, indicating that the helium emission originates from the circumstellar environment rather than the SN ejecta. Based on the modeling of the remaining 42 SNe Iax, we find no obvious helium features in other SN Iax spectra. However, $\approx 76\%$ of our sample lack sufficiently deep luminosi…
The lines-of-sight to highly reddened SNe Ia show peculiar continuum polarization curves, growing toward blue wavelengths and peaking at $λ_{max} \lesssim 0.4 μm$, like no other sight line to any normal Galactic star. We examined continuum polarization measurements of a sample of asymptotic giant branch (AGB) and post-AGB stars from the literature, finding that some PPNe have polarization curves similar to those observed along SNe Ia sight lines. Those polarization curves are produced by scattering on circumstellar dust. We discuss the similarity and the possibility that at least some SNe Ia m…
Type Ia supernovae (SNe Ia) play a prominent role in understanding the evolution of Universe. They are thought to be thermonuclear explosions of mass-accreting carbon-oxygen white dwarfs (CO WDs) in binaries, although the mass donors of the accreting WDs are still not well determined. In this article, I review recent studies on mass-accreting WDs, including H- and He-accreting WDs. I also review currently most studied progenitor models of SNe Ia, i.e., the single-degenerate model (including the WD+MS channel, the WD+RG channel and the WD+He star channel), the double-degenerate model (including…
Natures of progenitors of type Ia Supernovae (SNe Ia) have not yet been clarified. There has been long and intensive discussion on whether the so-called single degenerate (SD) scenario or the double degenerate (DD) scenario, or anything else, could explain a major population of SNe Ia, but the conclusion has not yet been reached. With rapidly increasing observational data and new theoretical ideas, the field of studying the SN Ia progenitors has been quickly developing, and various new insights have been obtained in recent years. This article aims at providing a summary of the current situatio…
