SNe IIP Research Articles

GALEXDETECTION OF SHOCK BREAKOUT IN TYPE IIP SUPERNOVA PS1-13arp: IMPLICATIONS FOR THE PROGENITOR STAR WIND

We present the GALEX detection of a UV burst at the time of explosion of an optically normal Type II-P supernova (PS1-13arp) from the Pan-STARRS1 survey at z=0.1665. The temperature and luminosity of the UV burst match the theoretical predictions for shock breakout in a red supergiant, but with a duration a factor of ~50 longer than expected. We compare the $NUV$ light curve of PS1-13arp to previous GALEX detections of Type IIP SNe, and find clear distinctions that indicate that the UV emission is powered by shock breakout, and not by the subsequent cooling envelope emission previously detected in these systems. We interpret the ~ 1 d duration of the UV signal with a shock breakout in the wind of a red supergiant with a pre-explosion mass-loss rate of ~ 10^-3 Msun yr^-1. This mass-loss rate is enough to prolong the duration of the shock breakout signal, but not enough to produce an excess in the optical plateau light curve or narrow emission lines powered by circumstellar interaction. This detection of non-standard, potentially episodic high mass-loss in a RSG SN progenitor has favorable consequences for the prospects of future wide-field UV surveys to detect shock breakout directly in these systems, and provide a sensitive probe of the pre-explosion conditions of SN progenitors.

PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

PTF11iqb was initially classified as a TypeIIn event caught very early after explosion. It showed narrow Wolf-Rayet (WR) spectral features on day 2, but the narrow emission weakened quickly and the spectrum morphed to resemble those of Types II-L and II-P. At late times, Halpha emission exhibited a complex, multipeaked profile reminiscent of SN1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN~1998S, although with weaker interaction with circumstellar material (CSM) at early times, and stronger CSM interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for weak CSM interaction added to the light curve of a normal SN~II-P. This plateau requires that the progenitor had an extended H envelope like a red supergiant, consistent with the slow progenitor wind speed indicated by narrow emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum --- meaning that the presence of such WR features in an early SN spectrum does not necessarily indicate a WR-like progenitor. [abridged] Overall, PTF11iqb bridges SNe~IIn with weaker pre-SN mass loss seen in SNe II-L and II-P, implying a continuum between these types.

Parameters of type IIP SN 2012A and clumpiness effects

The explosion energy and the ejecta mass of a type IIP supernova (SN IIP) derived from hydrodynamic simulations are principal parameters of the explosion theory. However, the number of SNe IIP studied by hydrodynamic modeling is small. Moreover, some doubts exist in regard to the reliability of derived SN IIP parameters. The well-observed type IIP SN 2012A will be studied via hydrodynamic modeling. Their early spectra will be checked for a presence of the ejecta clumpiness. Other observational effects of clumpiness will be explored. Supernova parameters are determined by means of the standard hydrodynamic modeling. The early hydrogen Halpha and Hbeta lines are used for the clumpiness diagnostics. The modified hydrodynamic code is employed to study the clumpiness effect in the light curve and expansion kinematics. We found that SN 20012A is the result of the explosion of a red supergiant with the radius of 715 Rsun. The explosion energy is 5.25x10^50 erg, the ejecta mass is 13.1 Msun, and the total Ni-56 mass is 0.012 Msun. The estimated mass of a progenitor, a main-sequence star, is 15 Msun. The Halpha and Hbeta lines in early spectra indicate that outer ejecta are clumpy. Hydrodynamic simulations show that the clumpiness modifies the early light curve and increases the maximum velocity of the outer layers. The pre-SN 2012A was a normal red supergiant with the progenitor mass of about 15 Msun. The outer layers of ejecta indicate the clumpy structure. The clumpiness of the external layers can increase the maximum expansion velocity.

SN 2012ec: mass of the progenitor from PESSTO follow-up of the photospheric phase

We present the results of a photometric and spectroscopic monitoring campaign of SN 2012ec, which exploded in the spiral galaxy NGC 1084, during the photospheric phase. The photometric light curve exhibits a plateau with luminosity L= 0.9 x 10^{42} erg/s and duration ~90 days, which is somewhat shorter than standard Type II-P supernovae. We estimate the nickel mass as 0.040 +/- 0.015 Msun from the luminosity at the beginning of the radioactive tail of the light curve. The explosion parameters of SN 2012ec were estimated from the comparison of the bolometric light curve and the observed temperature and velocity evolution of the ejecta with predictions from hydrodynamical models. We derived an envelope mass of 12.6 Msun, an initial progenitor radius of 1.6 x 10^{13} cm and an explosion energy of 1.2 foe. These estimates agree with an independent study of the progenitor star identified in pre-explosion images, for which an initial mass of M=14-22 Msun was determined. We have applied the same analysis to two other type II-P supernovae (SNe 2012aw and 2012A), and carried out a comparison with the properties of SN 2012ec derived in this paper. We find a reasonable agreement between the masses of the progenitors obtained from pre-explosion images and masses derived from hydrodynamical models. We estimate the distance to SN 2012ec with the Standardized Candle Method (SCM) and compare it with other estimates based on other primary and secondary indicators. SNe 2012A, 2012aw and 2012ec all follow the standard relations for the SCM for the use of Type II-P SNe as distance indicators.

TOWARD CHARACTERIZATION OF THE TYPE IIP SUPERNOVA PROGENITOR POPULATION: A STATISTICAL SAMPLE OF LIGHT CURVES FROM Pan-STARRS1

In recent years, wide-field sky surveys providing deep multi-band imaging have presented a new path for indirectly characterizing the progenitor populations of core-collapse supernovae (SN): systematic light curve studies. We assemble a set of 76 grizy-band Type IIP SN light curves from Pan-STARRS1, obtained over a constant survey program of 4 years and classified using both spectroscopy and machine learning-based photometric techniques. We develop and apply a new Bayesian model for the full multi-band evolution of each light curve in the sample. We find no evidence of a sub-population of fast-declining explosions (historically referred to as "Type IIL" SNe). However, we identify a highly significant relation between the plateau phase decay rate and peak luminosity among our SNe IIP. These results argue in favor of a single parameter, likely determined by initial stellar mass, predominantly controlling the explosions of red supergiants. This relation could also be applied for supernova cosmology, offering a standardizable candle good to an intrinsic scatter of 0.2 mag. We compare each light curve to physical models from hydrodynamic simulations to estimate progenitor initial masses and other properties of the Pan-STARRS1 Type IIP SN sample. We show that correction of systematic discrepancies between modeled and observed SN IIP light curve properties and an expanded grid of progenitor properties, are needed to enable robust progenitor inferences from multi-band light curve samples of this kind. This work will serve as a pathfinder for photometric studies of core-collapse SNe to be conducted through future wide field transient searches.

Supernova spectra below strong circumstellar interaction

We construct spectra of supernovae interacting strongly with a circumstellar medium (CSM) by adding SN templates, a black-body continuum and an emission-line spectrum. In a Monte Carlo simulation we generate more than 800 spectra, distribute them to 10 different classifiers and study how the different simulation parameters affect the appearance of the spectra. SNe IIn showing some structure over the continuum were characterized as SNe IInS. We demonstrate that the flux ratio of the underlying SN to the continuum fv is the most important parameter determining the spectral classification. Thermonuclear SNe get progressively classified as Ia-CSM, IInS and IIn as fv decreases. The transition between Ia-CSM and IInS occurs at fv~0.2-0.3. It shown that SNe Ia-CSM are found at the magnitude range -19.5> M >-21.6, in good agreement with observations, and that the faintest SN IIn that can hide a SN Ia has M = -20.1. The sample of SNe Ia-CSM shows an association with 91T-like SNe Ia. Our experiment does not support that this association is due to a luminosity bias (91T-like being brighter than normal Ia). We therefore conclude that this association has real physical origins and we propose that 91T-like explosions result from single degenerate progenitors. Despite the similarities between SNe Ibc and SNe Ia, the number of misclassifications between these types was small and mostly at low S/N. Combined with the luminosity function needed to reproduce the observed SN Ia-CSM luminosities, it is unlikely that SNe Ibc constitute an important contaminant within this sample. We show how Type II spectra transition to IIn and how the Ha profiles vary with fv. SNe IIn fainter than M = -17.2 are unable to mask SNe IIP brighter than M = -15. A simulation including radiative transfer shows that our simplified model is a good first order approximation. The spectra obtained are in good agreement with real data.

OPTICAL AND ULTRAVIOLET OBSERVATIONS OF A LOW-VELOCITY TYPE II PLATEAU SUPERNOVA 2013am IN M65

Optical and ultraviolet observations for the nearby type II-plateau supernova (SN IIP) 2013am in the nearby spiral galaxy M65 are presented in this paper. The early spectra are characterized by relatively narrow P-Cygni features, with ejecta velocities much lower than observed in normal SNe IIP (i.e., $\sim$2000 km s$^{-1}$ vs. $\sim$5000 km $^{-1}$ in the middle of the plateau phase). Moreover, prominent Ca II absorptions are also detected in SN 2013am at relatively early phases. These spectral features are reminiscent of those seen in the low-velocity and low-luminosity SN IIP 2005cs. However, SN 2013am exhibits different photometric properties, having shorter plateau phases and brighter light-curve tails if compared to SN 2005cs. Adopting $R_{V}$=3.1 and a mean value of total reddening derived from the photometric and spectroscopic methods(i.e., $E(B-V)=0.55\pm$0.19 mag), we find that SN 2013am may have reached an absolute $V$-band peak magnitude of $-15.83\pm0.71$ mag, and produced a $^{56}$Ni mass of $0.016^{+0.010}_{-0.006} solar masses in the explosion. These parameters are close to those derived for SN 2008in and SN 2009N which have been regarded as "gap-filler" objects linking the faint SNe IIP to the normal ones. This indicates that some low-velocity SNe IIP may not necessarily result from the low-energetic explosions, and the low expansion velocities could be due to a lower metallicity of the progenitor stars, a larger envelope mass ejected in the explosion, or that is was observed at an angle that is away from the polar direction.

A sample of Type II-L supernovae

What are Type II-Linear supernovae (SNe II-L)? This class, which has been ill defined for decades, now receives significant attention -- both theoretically, in order to understand what happens to stars in the ~15-25Mo range, and observationally, with two independent studies suggesting that they cannot be cleanly separated photometrically from the regular hydrogen-rich SNe II-P characterised by a marked plateau in their light curve. Here, we analyze the multi-band light curves and extensive spectroscopic coverage of a sample of 35 SNe II and find that 11 of them could be SNe II-L. The spectra of these SNe are hydrogen deficient, typically have shallow Halpha absorption, may show indirect signs of helium via strong OI 7774 absorption, and have faster line velocities consistent with a thin hydrogen shell. The light curves can be mostly differentiated from those of the regular, hydrogen-rich SNe II-P by their steeper decline rates and higher luminosity, and we propose as a defining photometric characteristic the decline in the V band: SNe II-L seem to decline by more than 0.5 mag from peak brightness by day 50 after explosion. Using our sample we provide template light curves for SNe II-L and II-P in 4 photometric bands.

Photometric and spectroscopic properties of Type II-P supernovae

We study a sample of 23 Type II Plateau supernovae (SNe II-P), all observed with the same set of instruments. Analysis of their photometric evolution confirms that their typical plateau duration is 100 days with little scatter, showing a tendency to get shorter for more energetic SNe. The rise time from explosion to plateau does not seem to correlate with luminosity. We analyze their spectra, measuring typical ejecta velocities, and confirm that they follow a well behaved power-law decline. We find indications of high-velocity material in the spectra of six of our SNe. We test different dust extinction correction methods by asking the following -- does the uniformity of the sample increase after the application of a given method? A reasonably behaved underlying distribution should become tighter after correction. No method we tested made a significant improvement.

Environments of interacting transients: impostors and Type IIn supernovae

This paper presents one of the first environmental analyses of the locations of the class of `interacting transients', namely type IIn supernovae and supernova Impostors. We discuss the association of these transients with star formation, host galaxy type, metallicity, and the locations of each event within the respective host. Given the frequent assumption of very high mass progenitors for these explosions from various studies, most notably a direct progenitor detection, it is interesting to note the weak association of these subtypes with star formation as traced by H{\alpha} emission, particularly in comparison with type Ic supernovae, which trace the H{\alpha} emission and are thought to arise from high mass progenitors. The radial distributions of these transients compared to type Ic supernovae are also very different. This provides evidence for the growing hypothesis that these `interacting transients' are in fact comprised of a variety of progenitor systems. The events contained within this sample are discussed in detail, where information in the literature exists, and compared to the environmental data provided. Impostors are found to split into two main classes, in terms of environment: SN2008S-like Impostors fall on regions of zero H{\alpha} emission, whereas {\eta}-Carina-like Impostors all fall on regions with positive H{\alpha} emission. We also find indications that the Impostor class originate from lower metallicity environments than type IIn, Ic and IIP SNe.

Low luminosity Type II supernovae – II. Pointing towards moderate mass precursors

We present new data for five underluminous Type II-plateau supernovae (SNe IIP), namely SN 1999gn, SN 2002gd, SN 2003Z, SN 2004eg and SN 2006ov. This new sample of low-luminosity SNe IIP (LL SNe IIP) is analysed together with similar objects studied in the past. All of them show a flat light-curve plateau lasting about 100 d, an underluminous late-time exponential tail, intrinsic colours that are unusually red, and spectra showing prominent and narrow P Cygni lines. A velocity of the ejected material below 103 km s−1 is inferred from measurements at the end of the plateau. The 56Ni masses ejected in the explosion are very small (≤10−2 M⊙). We investigate the correlations among 56Ni mass, expansion velocity of the ejecta and absolute magnitude in the middle of the plateau, confirming the main findings of Hamuy, according to which events showing brighter plateau and larger expansion velocities are expected to produce more 56Ni. We propose that these faint objects represent the LL tail of a continuous distribution in parameters space of SNe IIP. The physical properties of the progenitors at the explosion are estimated through the hydrodynamical modelling of the observables for two representative events of this class, namely SN 2005cs and SN 2008in. We find that the majority of LL SNe IIP, and quite possibly all, originate in the core collapse of intermediate-mass stars, in the mass range 10–15 M⊙.

A late-time view of the progenitors of five Type IIP supernovae

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 significant doubt over the nature of the source previously identified as the progenitor in pre-explosion WFPC2 images. The use of image subtraction techniques yields improved precision over photometry conducted on just the pre-explosion images alone. In particular, we note the increased depth of detection limits derived on pre-explosion frames in conjunction with late-time images. We use SED fitting techniques to explore the effect of different reddening components towards the progenitors. For SNe 2003gd and 2005cs, the pre-explosion observations are sufficiently constraining that only limited amounts of dust (either interstellar or circumstellar) are permitted. Assuming only a Galactic reddening law, we determine the initial masses for the progenitors of SNe 2003gd, 2004A, 2005cs and 2006my of 8.4+/-2.0, 12.0+/-2.1, 9.5(+3.4,-2.2) and 9.8+/-1.7Msun, respectively.

A metallicity study of 1987A-like supernova host galaxies

The origin of the blue supergiant (BSG) progenitor of Supernova (SN) 1987A has long been debated, along with the role that its sub-solar metallicity played. We now have a sample of 1987A-like SNe that arise from the core collapse (CC) of BSGs. The metallicity of the explosion sites of the known BSG SNe is investigated, as well as their association to star-forming regions. Both indirect and direct metallicity measurements of 13 BSG SN host galaxies are presented, and compared to those of other CC SN types. Indirect measurements are based on the known luminosity-metallicity relation and on published metallicity gradients of spiral galaxies. To provide direct estimates based on strong line diagnostics, we obtained spectra of each BSG SN host both at the SN explosion site and at the positions of other HII regions. Continuum-subtracted Ha images allowed us to quantify the association between BSG SNe and star-forming regions. BSG SNe explode either in low-luminosity galaxies or at large distances from the nuclei of luminous hosts. Therefore, their indirectly measured metallicities are typically lower than those of SNe IIP and Ibc. This is confirmed by the direct estimates, which show slightly sub-solar values (12+log(O/H)=8.3-8.4 dex), similar to that of the Large Magellanic Cloud (LMC), where SN 1987A exploded. However, two SNe (1998A and 2004em) were found at near solar metallicity. SNe IIb have a metallicity distribution similar to that of BSG SNe. Finally, the association to star-forming regions is similar among BSG SNe, SNe IIP and IIn. Our results suggest that LMC metal abundances play a role in the formation of some 1987A-like SNe. This would naturally fit in a single star scenario for the progenitors. However, the existence of two events at nearly solar metallicity suggests that also other channels, e.g. binarity, contribute to produce BSG SNe.

Comparison of progenitor mass estimates for the Type IIP SN 2012A

We present the one-year long observing campaign of SN 2012A which exploded in the nearby (9.8 Mpc) irregular galaxy NGC 3239. The photometric evolution is that of a normal type IIP supernova. The absolute maximum magnitude, with MB = -16.23 +- 0.16 mag. SN2012A reached a peak luminosity of about 2X10**42 erg/s, which is brighter than those of other SNe with a similar 56Ni mass. The latter was estimated from the luminosity in the exponential tail of the light curve and found to be M(56Ni) = 0.011 +-0.004 Msun. The spectral evolution of SN 2012A is also typical of SN IIP, from the early spectra dominated by a blue continuum and very broad (~10**4 km/s) Balmer lines, to the late-photospheric spectra characterized by prominent P-Cygni features of metal lines (Fe II, Sc II, Ba II, Ti II, Ca II, Na ID). The photospheric velocity is moderately low, ~3X10**3 km/s at 50 days, for the low optical depth metal lines. The nebular spectrum obtained 394 days after the shock breakout shows the typical features of SNe IIP and the strength of the [O I] doublet suggests a progenitor of intermediate mass, similar to SN 2004et (~15 Msun). A candidate progenitor for SN 2012A has been identified in deep, pre-explosion K'-band Gemini North (NIRI) images, and found to be consistent with a star with a bolometric magnitude -7.08+-0.36 (log L/Lsun = 4.73 +- 0.14$ dex). The magnitude of the recovered progenitor in archival images points toward a moderate-mass 10.5 (-2/+4.5) Msun star as the precursor of SN 2012A. The explosion parameters and progenitor mass were also estimated by means of a hydrodynamical model, fitting the bolometric light curve, the velocity and the temperature evolution. We found a best fit for a kinetic energy of 0.48 foe, an initial radius of 1.8X10**13 cm and ejecta mass of 12.5 Msun.

Moderately luminous Type II supernovae

Core-collapse Supernovae (CC-SNe) descend from progenitors more massive than about 8 Msun. Because of the young age of the progenitors, the ejecta may eventually interact with the circumstellar medium (CSM) via highly energetic processes detectable in the radio, X-ray, ultraviolet (UV) and, sometimes, in the optical domains. In this paper we present ultraviolet, optical and near infrared observations of five type II SNe, namely SNe 2009dd, 2007pk, 2010aj, 1995ad, and 1996W. Together with few other SNe they form a group of moderately luminous type II events. We collected photometry and spectroscopy with several telescopes in order to construct well-sampled light curves and spectral evolutions from the photospheric to the nebular phases. Both photometry and spectroscopy indicate a degree of heterogeneity in this sample. The light curves have luminous peak magnitudes ($-16.95<M_{B}<-18.70$). The ejected masses of ^56\ni for three SNe span a wide range of values ($2.8\times10^{-2}$Msun$<$M(\ni)$<1.4\times10^{-1}$Msun), while for a fourth (SN2010aj) we could determine a stringent upper limit ($7\times10^{-3}$Msun). Clues of interaction, such as the presence of high velocity (HV) features of the Balmer lines, are visible in the photospheric spectra of SNe 2009dd and 1996W. For SN2007pk we observe a spectral transition from a type IIn to a standard type II SN. Modelling the observations of SNe 2009dd, 2010aj and 1995ad with radiation hydrodynamics codes, we infer kinetic plus thermal energies of about 0.2-0.5 foe, initial radii of 2-5$\times10^{13}$ cm and ejected masses of $\sim$5.0-9.5 Msun. These values suggest moderate-mass, super-asymptotic giant branch (SAGB) or red super-giants (RSG) stars as SN precursors, in analogy with other luminous type IIP SNe 2007od and 2009bw.

Supernova 2012aw – a high-energy clone of archetypal Type IIP SN 1999em

We present densely-sampled UBVRI/griz photometric and low-resolution (6-10A) optical spectroscopic observations from 4 to 270 days after explosion of a newly discovered type II SN 2012aw in a nearby (~9.9 Mpc) galaxy M95. The light-curve characteristics of apparent magnitudes, colors, bolometric luminosity and the presence and evolution of prominent spectral features are found to have striking similarity with the archetypal IIP SNe 1999em, 1999gi and 2004et. The early time observations of SN 2012aw clearly detect minima in the light-curve of V, R and I bands near 37 days after explosion and this we suggest to be an observational evidence for emergence of recombination phase. The mid-plateau MV magnitude (-16.67 $\pm$ 0.04) lies in between the bright (~ -18) and subluminous (~ -15) IIP SNe. The mass of nickel is 0.06$\pm$0.01 M_sun. The SYNOW modelling of spectra indicate that the value and evolution of photospheric velocity is similar to SN 2004et, but about ~600 km/s higher than that of SNe 1999em and 1999gi at comparable epochs. This trend is more apparent in the line velocities of H alpha and H beta. A comparison of ejecta velocity properties with that of existing radiation-hydrodynamical simulations indicate that the energy of explosion lies in the range 1-2x10^51 ergs; a further comparison of nebular phase [Oi] doublet luminosity with SNe 2004et and 1987A indicate that the mass of progenitor star is about 14-15 M_sun. The presence of high-velocity absorption features in the mid-to-late plateau and possibly in early phase spectra show signs of interaction between ejecta and the circumstellar matter; being consistent with its early-time detection at X-ray and radio wavebands.

X-ray and optical plateaus following the main bursts in GRBs and SNe II-P: a hint about similar late injection behaviors?

We analyze the emission plateaus in the X-ray afterglow light curves of gamma-ray bursts (GRBs) and those in the optical light curves of type II plateau supernovae (SNe II-P) in order to study whether they have similar late energy injection behaviors. We show that correlations of bolometric energies (or luminosities) between the prompt explosions and the plateaus for the two phenomena are similar. The energy emitted by SNe II-P are at the lower end of the range of possible energies for GRBs. The bolometric energies (or luminosities) in the prompt phase Eexpl (or Lexpl) and in the plateau phase Eplateau (or Lplateau) share relations of Eexpl ∝ E0.73±0.14plateau and Lexpl ∝ L∼0.70plateau. These results may indicate a similar late energy injection behavior that produces the observed plateaus in these two phenomena.

THE 2012 RISE OF THE REMARKABLE TYPE IIn SN 2009ip

Recent observations by Mauerhan et al. have shown the unprecedented transition of the previously identified luminous blue variable (and supernova impostor) SN 2009ip to a real Type IIn supernova (SN) explosion. We present high-cadence optical imaging of SN 2009ip obtained between 2012 UT Sep. 23.6 and Oct. 9.6, using 0.3-0.4 meter aperture telescopes from the Coral Towers Observatory in Cairns, Australia. The light curves show well-defined phases, including very rapid brightening early on (0.5 mag in 6 hr observed during the night of Sep. 24), a transition to a much slower rise between Sep. 25 and Sep. 28, and a plateau/peak around Oct. 7. These changes are coincident with the reported spectroscopic changes that, most likely, mark the start of a strong interaction between the fast SN ejecta and a dense circumstellar medium formed during the earlier LBV eruptions. In the 16-day observing period SN 2009ip brightened by 3.7 mag from I = 17.4 mag on Sep. 23.6 (MI = -14.2) to I = 13.7 mag (MI = -17.9) on Oct. 9.6, radiating ~2x10^49 erg in the optical wavelength range. Currently, SN 2009ip is more luminous than most Type IIP SNe and comparable to other Type IIn SNe.

Multi-band optical light-curve behavior of core-collapse supernovae

AbstractWe present survey results obtained from the UBVRI optical photometric follow-up of 19 bright core-collapse SNe during 2002-2012 using 1-m class optical telescopes operated by the Aryabhatta Research Institute of Observational Science (acronym ARIES), Nainital India. This homogeneous set of data have been used to study behavior of optical light/color curve, and to gain insight into objet-to-object peculiarity. We derive integrated luminosities for types IIP, Ibc and luminous SNe. Two peculiar type IIP events having photometric properties similar to normal IIP and spectroscopic properties similar to sub-lumnious IIP have been identified.

A tale of two shocks in SN 2004dj

AbstractType IIP SNe constitute a major fraction of all core-collapse supernovae and arise from massive stars that end their lives close to Red Supergiants. The blastwave from the SN interacting with the progenitor's circumstellar matter produces a hot region bounded by a forward and a reverse shock from which most of the X-ray emission originates. Analysis of archival Chandra observations of SN 2004dj, one of the nearest supernovae since SN 1987A, together with published data from radio and optical bands determines the pre-explosion mass-loss rate, blastwave speed, electron acceleration and magnetic field amplification efficiencies. X-ray emission arises from both inverse Compton scattering by non-thermal electrons accelerated in the forward shock and from thermal emission from the supernova ejecta hit by the reverse shock. Determination of the properties of the radiating plasma based on the separation of thermal and non-thermal radiation differentiates different types of supernovae and their environments.