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.
ABSTRACT
SN 2009kf is an exceptionally bright Type IIP supernova (SN IIP) discovered by the Pan-STARRS 1 survey. The V-band magnitude in the plateau phase is MV = −18.4 mag, which is much brighter ...than that for typical SNe IIP. We propose that its unusual properties can be naturally explained if we assume that there was a super-Eddington energy injection into the envelope in the last few years of the evolution before the SN explosion. Using a progenitor model with such a pre-SN energy injection, we can fit the observational data of SN 2009kf with a reasonable explosion energy of Eexp = 2.8 × 1051 erg and 56Ni mass of 0.25 M⊙. Specifically, we injected the energy into the envelope at a constant rate of 3.0 × 1039 erg s−1 in the last 3.0 yr of evolution before the core collapse. We propose that some unusually bright SNe IIP might result from pre-SN energy injection into the envelope.
Recent works have indicated that the 56Ni masses estimated for stripped envelope supernovae (SESNe) are systematically higher than those estimated for SNe II. Although this may suggest a distinct ...progenitor structure between these types of SNe, the possibility remains that this may be caused by observational bias. One important possible bias is that SESNe with low 56Ni mass are dim, and therefore more likely to escape detection. By investigating the distributions of 56Ni mass and distance of the samples collected from the literature, we find that the current literature SESN sample indeed suffers from a significant observational bias, i.e., objects with low 56Ni mass—if they exist—will be missed, especially at larger distances. Note, however, that those distant objects in our sample are mostly SNe Ic-BL. We also conducted mock observations assuming that the 56Ni mass distribution for SESNe is intrinsically the same as that of SNe II. We find that the 56Ni mass distribution of the detected SESN samples moves toward higher mass than the assumed intrinsic distribution because of the difficulty in detecting the low-56Ni mass SESNe. These results could explain the general trend of the higher 56Ni mass distribution (than SNe II) of SESNe found thus far in the literature. However, further finding clear examples of low-56Ni mass SESNe (≤ 0.01 M ⊙) is required to strengthen this hypothesis. Also, objects with high 56Ni mass (≳ 0.2 M ⊙) are not explained by our model, which may require an additional explanation.
Recent observations of supernovae (SNe) just after the explosion suggest that a good fraction of SNe have the confined circumstellar material (CSM) in the vicinity, and the pre-SN enhanced mass loss ...may be a common property. The physical mechanism of this phenomenon is still unclarified, and the energy deposition into the envelope has been proposed as a possible cause of the confined CSM. In this work, we have calculated the response of the envelope to various types of sustained energy deposition starting from a few years before the core collapse. We have further investigated how the resulting progenitor structure would affect the appearance of the ensuing supernova. While it has been suspected that a super-Eddington energy deposition may lead to a strong and/or eruptive mass loss to account for the confined CSM, we have found that a highly super-Eddington energy injection into the envelope changes the structure of the progenitor star substantially, and the properties of the resulting SNe become inconsistent with typical SNe. This argument constrains the energy budget involved in the possible stellar activity in the final years to be at most one order of magnitude higher than the Eddington luminosity. Such an energy generation, however, would not dynamically develop a strong wind on a timescale of a few years. We therefore propose that a secondary effect (e.g., pulsation or binary interaction) triggered by moderate envelope inflation, which is caused by sub-Eddington energy injection, likely induces the mass loss.
ABSTRACT
Photometric and spectroscopic analyses of the intermediate-luminosity Type Ib supernova (SN) 2015ap and of the heavily reddened Type Ib SN 2016bau are discussed. Photometric properties of ...the two SNe, such as colour evolution, bolometric luminosity, photospheric radius, temperature, and velocity evolution, are also constrained. The ejecta mass, synthesized nickel mass, and kinetic energy of the ejecta are calculated from their light-curve analysis. We also model and compare the spectra of SN 2015ap and SN 2016bau at various stages of their evolution. The P Cygni profiles of various lines present in the spectra are used to determine the velocity evolution of the ejecta. To account for the observed photometric and spectroscopic properties of the two SNe, we have computed 12 M⊙ zero-age main-sequence (ZAMS) star models and evolved them until the onset of core-collapse using the publicly available stellar-evolution codeMESA. Synthetic explosions were produced using the public version of STELLA and another publicly available code, SNEC, utilizing the MESA models. SNEC and stella provide various observable properties such as the bolometric luminosity and velocity evolution. The parameters produced by SNEC/STELLA and our observations show close agreement with each other, thus supporting a 12 M⊙ ZAMS star as the possible progenitor for SN 2015ap, while the progenitor of SN 2016bau is slightly less massive, being close to the boundary between SN and non-SN as the final product.
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 H 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.
Abstract
Recent works have indicated that the
56
Ni masses estimated for stripped envelope supernovae (SESNe) are systematically higher than those estimated for SNe II. Although this may suggest a ...distinct progenitor structure between these types of SNe, the possibility remains that this may be caused by observational bias. One important possible bias is that SESNe with low
56
Ni mass are dim, and therefore more likely to escape detection. By investigating the distributions of
56
Ni mass and distance of the samples collected from the literature, we find that the current literature SESN sample indeed suffers from a significant observational bias, i.e., objects with low
56
Ni mass—if they exist—will be missed, especially at larger distances. Note, however, that those distant objects in our sample are mostly SNe Ic-BL. We also conducted mock observations assuming that the
56
Ni mass distribution for SESNe is intrinsically the same as that of SNe II. We find that the
56
Ni mass distribution of the detected SESN samples moves toward higher mass than the assumed intrinsic distribution because of the difficulty in detecting the low-
56
Ni mass SESNe. These results could explain the general trend of the higher
56
Ni mass distribution (than SNe II) of SESNe found thus far in the literature. However, further finding clear examples of low-
56
Ni mass SESNe (≤ 0.01
M
⊙
) is required to strengthen this hypothesis. Also, objects with high
56
Ni mass (≳ 0.2
M
⊙
) are not explained by our model, which may require an additional explanation.
ABSTRACT
In this work, photometric and spectroscopic analyses of a very low-luminosity Type IIb supernova (SN) 2016iyc have been performed. SN 2016iyc lies near the faint end among the distribution ...of similar supernovae (SNe). Given lower ejecta mass (Mej) and low nickel mass (MNi) from the literature, combined with SN 2016iyc lying near the faint end, one-dimensional stellar evolution models of 9–14 M⊙ zero-age main-sequence (ZAMS) stars as the possible progenitors of SN 2016iyc have been performed using the publicly available code mesa. Moreover, synthetic explosions of the progenitor models have been simulated, using the hydrodynamic evolution codes stella and snec. The bolometric luminosity light curve and photospheric velocities produced through synthetic explosions of ZAMS stars of mass in the range of 12–13 M⊙ having a pre-supernova radius R0 = (204–300) R⊙, with Mej = (1.89–1.93) M⊙, explosion energy Eexp = (0.28–0.35) × 1051 erg, and MNi < 0.09 M⊙, are in good agreement with observations; thus, SN 2016iyc probably exploded from a progenitor near the lower mass limits for SNe IIb. Finally, hydrodynamic simulations of the explosions of SN 2016gkg and SN 2011fu have also been performed to compare intermediate- and high-luminosity examples among well-studied SNe IIb. The results of progenitor modelling and synthetic explosions for SN 2016iyc, SN 2016gkg, and SN 2011fu exhibit a diverse range of mass for the possible progenitors of SNe IIb.
SN 2009kf is an exceptionally bright Type IIP Supernova (SN IIP) discovered by the Pan-STARRS 1 survey. The \(V\)-band magnitude at the plateau phase is \(M_{V} = -18.4\) mag, which is much brighter ...than typical SNe IIP. We propose that its unusual properties can be naturally explained, if we assume that there was an super-Eddington energy injection into the envelope in the last few years of the evolution before the SN explosion. Using a progenitor model with such an pre-SN energy injection, we can fit the observational data of SN 2009kf with the reasonable explosion energy of \(E_{\mathrm{exp}} = 2.8 \times 10^{51}\) erg and the \(^{56}\)Ni mass of \(0.25 M_{\odot}\). Specifically, we injected the energy into the envelope at a constant rate of \(3.0 \times 10^{39}\) erg s\(^{-1}\) in the last 3.0 years of evolution before the core collapse. We propose that some of the unusually bright SNe IIP might result from the pre-SN energy injection to the envelope.
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