scholarly journals SN 2016gsd: an unusually luminous and linear Type II supernova with high velocities

2020 ◽  
Vol 493 (2) ◽  
pp. 1761-1781 ◽  
Author(s):  
T M Reynolds ◽  
M Fraser ◽  
S Mattila ◽  
M Ergon ◽  
L Dessart ◽  
...  
Keyword(s):  
Light Curve ◽  
Massive Star ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Type Ii ◽  
High Luminosity ◽  
Linear Type ◽  
Circumstellar Material ◽  
Low Metallicity ◽  
Edge Tracing

ABSTRACT We present observations of the unusually luminous Type II supernova (SN) 2016gsd. With a peak absolute magnitude of V = −19.95 ± 0.08, this object is one of the brightest Type II SNe, and lies in the gap of magnitudes between the majority of Type II SNe and the superluminous SNe. Its light curve shows little evidence of the expected drop from the optically thick phase to the radioactively powered tail. The velocities derived from the absorption in H α are also unusually high with the blue edge tracing the fastest moving gas initially at 20 000 km s−1, and then declining approximately linearly to 15 000 km s−1 over ∼100 d. The dwarf host galaxy of the SN indicates a low-metallicity progenitor which may also contribute to the weakness of the metal lines in its spectra. We examine SN 2016gsd with reference to similarly luminous, linear Type II SNe such as SNe 1979C and 1998S, and discuss the interpretation of its observational characteristics. We compare the observations with a model produced by the jekyll code and find that a massive star with a depleted and inflated hydrogen envelope struggles to reproduce the high luminosity and extreme linearity of SN 2016gsd. Instead, we suggest that the influence of interaction between the SN ejecta and circumstellar material can explain the majority of the observed properties of the SN. The high velocities and strong H α absorption present throughout the evolution of the SN may imply a circumstellar medium configured in an asymmetric geometry.

scholarly journals Supernovae from blue supergiant progenitors: What a mess!

2019 ◽  
Vol 622 ◽  
pp. A70 ◽  
Author(s):  
Luc Dessart ◽  
D. John Hillier
Keyword(s):  
Light Curve ◽  
Line Width ◽  
Spectroscopic Properties ◽  
Blue Color ◽  
Type Ii ◽  
Spectral Evolution ◽  
Sn 1987A ◽  
Rich Diversity ◽  
Alternative Power ◽  
Low Metallicity

Supernova (SN) 1987A was classified as a peculiar Type II SN because of its long rising light curve and the persistent presence of H I lines in optical spectra. It was subsequently realized that its progenitor was a blue supergiant (BSG), rather than a red supergiant (RSG) as for normal, Type II-P, SNe. Since then, the number of Type II-pec SNe has grown, revealing a rich diversity in photometric and spectroscopic properties. In this study, using a single 15 M⊙ low-metallicity progenitor that dies as a BSG, we have generated explosions with a range of energies and 56Ni masses. We then performed the radiative transfer modeling with CMFGEN, from 1 d until 300 d after explosion for all ejecta. Our models yield light curves that rise to optical maximum in about 100 d, with a similar brightening rate, and with a peak absolute V-band magnitude spanning −14 to −16.5 mag. All models follow a similar color evolution, entering the recombination phase within a few days of explosion, and reddening further until the nebular phase. Their spectral evolution is analogous, mostly differing in line width. With this model set, we study the Type II-pec SNe 1987A, 2000cb, 2006V, 2006au, 2009E, and 2009mw. The photometric and spectroscopic diversity of observed SNe II-pec suggests that there is no prototype for this class. All these SNe brighten to maximum faster than our limited set of models, except perhaps SN 2009mw. The spectral evolution of SN 1987A conflicts with other observations in this set and conflicts with model predictions from 20 d until maximum: Hα narrows and weakens while Ba II lines strengthen faster than expected, which we interpret as signatures of clumping. SN 2000cb rises to maximum in only 20 d and shows weak Ba II lines. Its spectral evolution (color, line width and strength) is well matched by an energetic ejecta but the light curve may require strong asymmetry. The persistent blue color, narrow lines, and weak Hα absorption, seen in SN 2006V conflicts with expectations for a BSG explosion powered by 56Ni and may require an alternative power source. In contrast with theoretical expectations, observed spectra reveal a diverse behavior for lines like Ba II 6142 Å, Na I D, and Hα. In addition to diversity arising from different BSG progenitors, we surmise that their ejecta are asymmetric, clumped, and, in some cases, not solely powered by 56Ni decay.

scholarly journals The Flavours of SN II Light Curves

2011 ◽  
Vol 7 (S279) ◽  
pp. 34-39 ◽  
Author(s):  
Iair Arcavi
Keyword(s):  
Light Curve ◽  
Rare Events ◽  
Light Curves ◽  
Host Galaxy ◽  
Core Collapse ◽  
Type Ii

AbstractWe present R-Band light curves of Type II supernovae (SNe) from the Caltech Core Collapse Program (CCCP). With the exception of interacting (Type IIn) SNe and rare events with long rise times, we find that most light curve shapes belong to one of three distinct classes: plateau, slowly declining and rapidly declining events. The latter class is composed solely of Type IIb SNe which present similar light curve shapes to those of SNe Ib, suggesting, perhaps, similar progenitor channels. We do not find any intermediate light curves, implying that these subclasses are unlikely to reflect variance of continuous parameters, but rather might result from physically distinct progenitor systems, strengthening the suggestion of a binary origin for at least some stripped SNe. We find a large plateau luminosity range for SNe IIP, while the plateau lengths seem rather uniform at approximately 100 days. We present also host galaxy trends from the Palomar Transien Factory (PTF) core collapse SN sample, which augment some of the photometric results.

scholarly journals AT 2019abn: multi-wavelength observations over the first 200 days

2020 ◽  
Vol 637 ◽  
pp. A20 ◽  
Author(s):  
S. C. Williams ◽  
D. Jones ◽  
P. Pessev ◽  
S. Geier ◽  
R. L. M. Corradi ◽  
...  
Keyword(s):  
Light Curve ◽  
Near Infrared ◽  
Infrared Imaging ◽  
Absolute Magnitude ◽  
Low Velocity ◽  
Optical Telescope ◽  
Circumstellar Material ◽  
Medium Resolution ◽  
Multi Wavelength ◽  
Optical Light Curve

Context. AT 2019abn was discovered in the nearby M51 galaxy by the Zwicky Transient Facility at more than two magnitudes and around three weeks prior to its optical peak. Aims. We aim to conduct a detailed photometric and spectroscopic follow-up campaign for AT 2019abn, with early discovery allowing for significant pre-maximum observations of an intermediate luminosity red transient (ILRT) for the first time. Methods. This work is based on the analysis of u′BVr′i′z′H photometry and low-resolution spectroscopy using the Liverpool Telescope, medium-resolution spectroscopy with the Gran Telescopio Canarias (GTC), and near-infrared imaging with the GTC and the Nordic Optical Telescope. Results. We present the most detailed optical light curve of an ILRT to date, with multi-band photometry starting around three weeks before peak brightness. The transient peaked at an observed absolute magnitude of Mr′ = −13.1, although it is subject to significant reddening from dust in M51, implying an intrinsic Mr′ ∼ −15.2. The initial light curve showed a linear, achromatic rise in magnitude before becoming bluer at peak. After peak brightness, the transient gradually cooled. This is reflected in our spectra, which at later times show absorption from such species as Fe I, Ni I and Li I. A spectrum taken around peak brightness shows narrow, low-velocity absorption lines, which we interpret as likely to originate from pre-existing circumstellar material. Conclusions. We conclude that while there are some peculiarities, such as the radius evolution, AT 2019abn fits in well overall with the ILRT class of objects and is the most luminous member of the class seen to date.

scholarly journals Final Moments. I. Precursor Emission, Envelope Inflation, and Enhanced Mass Loss Preceding the Luminous Type II Supernova 2020tlf

2022 ◽  
Vol 924 (1) ◽  
pp. 15
Author(s):  
W. V. Jacobson-Galán ◽  
L. Dessart ◽  
D. O. Jones ◽  
R. Margutti ◽  
D. L. Coppejans ◽  
...  
Keyword(s):  
Light Curve ◽  
Mass Loss ◽  
Loss Rate ◽  
Main Sequence ◽  
Mass Loss Rate ◽  
Type Ii ◽  
Stellar Envelope ◽  
Circumstellar Material ◽  
Associated Mass ◽  
Flash Spectroscopy

Abstract We present panchromatic observations and modeling of supernova (SN) 2020tlf, the first normal Type II-P/L SN with confirmed precursor emission, as detected by the Young Supernova Experiment transient survey. Pre-SN activity was detected in riz-bands at −130 days and persisted at relatively constant flux until first light. Soon after discovery, “flash” spectroscopy of SN 2020tlf revealed narrow, symmetric emission lines that resulted from the photoionization of circumstellar material (CSM) shed in progenitor mass-loss episodes before explosion. Surprisingly, this novel display of pre-SN emission and associated mass loss occurred in a red supergiant (RSG) progenitor with zero-age main-sequence mass of only 10–12 M ⊙, as inferred from nebular spectra. Modeling of the light curve and multi-epoch spectra with the non-LTE radiative-transfer code CMFGEN and radiation-hydrodynamical code HERACLES suggests a dense CSM limited to r ≈ 1015 cm, and mass-loss rate of 10−2 M ⊙ yr−1. The luminous light-curve plateau and persistent blue excess indicates an extended progenitor, compatible with an RSG model with R ⋆ = 1100 R ⊙. Limits on the shock-powered X-ray and radio luminosity are consistent with model conclusions and suggest a CSM density of ρ < 2 × 10−16 g cm−3 for distances from the progenitor star of r ≈ 5 × 1015 cm, as well as a mass-loss rate of M ̇ < 1.3 × 10 − 5 M ☉ yr − 1 at larger distances. A promising power source for the observed precursor emission is the ejection of stellar material following energy disposition into the stellar envelope as a result of gravity waves emitted during either neon/oxygen burning or a nuclear flash from silicon combustion.

scholarly journals The luminous host galaxy, faint supernova and rapid afterglow rebrightening of GRB 100418A

2018 ◽  
Vol 620 ◽  
pp. A190 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
K. Bensch ◽  
A. J. van der Horst ◽  
D. A. Kann ◽  
...  
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Formation Rate ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Absorption And Emission ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Central Engine

Context. Long gamma-ray bursts (GRBs) give us the chance to study both their extreme physics and the star-forming galaxies in which they form. Aims. GRB 100418A, at a redshift of z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission. Methods. We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova (SN) and three X-shooter spectra obtained during the first 60 h. Results. The light curve shows a very fast optical rebrightening, with an amplitude of ∼3 magnitudes, starting 2.4 h after the GRB onset. This cannot be explained by a standard external shock model and requires other contributions, such as late central-engine activity. Two weeks after the burst we detect an excess in the light curve consistent with a SN with peak absolute magnitude MV = −18.5 mag, among the faintest GRB-SNe detected to date. The host galaxy shows two components in emission, with velocities differing by 130 km s−1, but otherwise having similar properties. While some absorption and emission components coincide, the absorbing gas spans much higher velocities, indicating the presence of gas beyond the star-forming regions. The host has a star formation rate of SFR = 12.2 M⊙ yr−1, a metallicity of 12 + log(O/H) = 8.55, and a mass of 1.6 × 109 M⊙. Conclusions. GRB 100418A is a member of a class of afterglow light curves which show a steep rebrightening in the optical during the first day, which cannot be explained by traditional models. Its very faint associated SN shows that GRB-SNe can have a larger dispersion in luminosities than previously seen. Furthermore, we have obtained a complete view of the host of GRB 100418A owing to its spectrum, which contains a remarkable number of both emission and absorption lines.

scholarly journals Type II Supernovae in Binary Systems

1996 ◽  
Vol 165 ◽  
pp. 141-149
Author(s):  
P.C. Joss
Keyword(s):  
Binary Systems ◽  
Massive Star ◽  
Light Curves ◽  
Close Binary ◽  
Type Ii ◽  
Substantial Fraction ◽  
Circumstellar Material ◽  
Common Envelope ◽  
Monte Carlo Calculations ◽  
Sn 1987A

The presence of a close binary companion can affect the evolution of a massive star through one or more episodes of mass transfer, or by merger in a common-envelope phase. Monte Carlo calculations indicate that ∼20–35% of all massive supernovae are affected by such processes, and that a substantial fraction of these events will be supernovae of type II. The properties of the progenitor star, the distribution of circumstellar material, the peak supernova luminosity, the shape of the supernova light curve, and other observable features of the supernova event can be affected by prior binary membership. Binary interactions may be the cause of much of the variability among type II supernova light curves. In particular, many of the peculiarities of SN 1987A and SN 1993J may well have resulted from the prior duplicity of the progenitors.

scholarly journals Numerical modeling of the 1840s major eruption of η Carinae as an explosion

2018 ◽  
Vol 609 ◽  
pp. A69 ◽  
Author(s):  
Ricardo F. González
Keyword(s):  
Total Mass ◽  
Massive Star ◽  
Type Ii ◽  
Bipolar Structure ◽  
Circumstellar Material ◽  
Dense Shell ◽  
Hydrodynamical Simulations ◽  
Short Time ◽  
Major Eruption ◽  
Explosive Event

In this paper, new two-dimensional hydrodynamical simulations of η Car’s nebulae are performed. In the 1840s, the massive star η Car suffered a major eruption that resulted in the formation of a bipolar structure, which is commonly known as the large Homunculus. During this event, η Car expelled into the circumstellar material a total mass of ~10 M⊙ and released a total energy of Ek ~ 1050 erg over a very short time (≤5 yr). These kinds of explosive events are frequently called supernova impostors due to their resemblance to a type II supernova, but the stars survive the explosion. In the case of η Car, a brief explosion scenario provides a potential explanation for the behavior of the historical light curve of η Car a few years (~10 yr) after the nineteenth century outburst. Here, such an alternative scenario of an explosion is assumed (instead of a super-Eddington wind) in order to investigate whether an explosive event is also able to explain the shape and kinematics of the large Homunculus. I show that the numerical simulations presented here indeed resemble some of the observed features of the nebula, such as the present-day double-shell structure of the Homunculus, with a thin outer dense shell and a thicker inner layer, as well as thermal instabilities (Rayleigh-Taylor and Kelvin-Helmholtz) along the dense shell that may lead to the current mottled appearance of the large Homunculus. Nonetheless, the explosion model for the 1840s major eruption of η Car is not able to account for the estimated age of the large Homunculus.

scholarly journals SN 2016B a.k.a. ASASSN-16ab: a transitional Type II supernova

2019 ◽  
Vol 486 (2) ◽  
pp. 2850-2872 ◽  
Author(s):  
Raya Dastidar ◽  
Kuntal Misra ◽  
Mridweeka Singh ◽  
D K Sahu ◽  
A Pastorello ◽  
...  
Keyword(s):  
Kinetic Energy ◽  
Light Curve ◽  
High Velocity ◽  
Type Ii ◽  
Plateau Phase ◽  
Initial Radius ◽  
Circumstellar Material ◽  
Transitional Type ◽  
Material Interaction

Abstract We present photometry, polarimetry, and spectroscopy of the Type II supernova ASASSN-16ab/SN 2016B in PGC 037392. The photometric and spectroscopic follow-up commenced about 2 weeks after shock breakout and continued until nearly 6 months. The light curve of SN 2016B exhibits intermediate properties between those of Type IIP and IIL. The early decline is steep (1.68 ± 0.10 mag 100 d−1), followed by a shallower plateau phase (0.47 ± 0.24 mag 100 d−1). The optically thick phase lasts for 118 d, similar to Type IIP. The 56Ni mass estimated from the radioactive tail of the bolometric light curve is 0.082 ± 0.019 M⊙. High-velocity component contributing to the absorption trough of H α and H β in the photospheric spectra are identified from the spectral modelling from about 57–97 d after the outburst, suggesting a possible SN ejecta and circumstellar material interaction. Such high-velocity features are common in the spectra of Type IIL supernovae. By modelling the true bolometric light curve of SN 2016B, we estimated a total ejected mass of ∼15 M⊙, kinetic energy of ∼1.4 foe, and an initial radius of ∼400 R⊙.

scholarly journals SN 2015an: a normal luminosity type II supernova with low expansion velocity at early phases

2019 ◽  
Vol 490 (2) ◽  
pp. 1605-1619
Author(s):  
Raya Dastidar ◽  
Kuntal Misra ◽  
Stefano Valenti ◽  
Jamison Burke ◽  
Griffin Hosseinzadeh ◽  
...  
Keyword(s):  
Light Curve ◽  
High Velocity ◽  
Expansion Velocity ◽  
Type Ii ◽  
Mass Yield ◽  
Circumstellar Material ◽  
V Band ◽  
Material Interaction ◽  
Early Phases ◽  
The Continuum

ABSTRACT We present the photometry and spectroscopy of SN 2015an, a type II Supernova (SN) in IC 2367. The recombination phase of the SN lasts up to 120 d, with a decline rate of 1.24 mag/100d, higher than the typical SNe IIP. The SN exhibits bluer colours than most SNe II, indicating higher ejecta temperatures. The absolute V-band magnitude of SN 2015an at 50 d is −16.83 ± 0.04 mag, pretty typical for SNe II. However, the 56Ni mass yield, estimated from the tail V-band light curve to be 0.021 ± 0.010 M⊙, is comparatively low. The spectral properties of SN 2015an are atypical, with low H α expansion velocity and presence of high-velocity component of H α at early phases. Moreover, the continuum exhibits excess blue flux up to 50 d, which is interpreted as a progenitor metallicity effect. The high-velocity feature indicates ejecta-circumstellar material interaction at early phases. The semi-analytical modelling of the bolometric light curve yields a total ejected mass of 12 M⊙, a pre-SN radius of 388 R⊙ and explosion energy of 1.8 foe.

scholarly journals Progenitors and Hydrodynamics of Type II and lb Supernovae

1996 ◽  
Vol 145 ◽  
pp. 137-147
Author(s):  
S. E. Woosley ◽  
T. A. Weaver ◽  
R. G. Eastman
Keyword(s):  
Black Holes ◽  
Light Curve ◽  
Mass Loss ◽  
Massive Stars ◽  
The Other ◽  
Shock Interaction ◽  
Type Ii ◽  
Residual Hydrogen ◽  
Ordinary Type ◽  
The One

We review critical physics affecting the observational characteristics of those supernovae that occur in massive stars. Particular emphasis is given to 1) how mass loss, either to a binary companion or by a radiatively driven wind, affects the type and light curve of the supernova, and 2) the interaction of the outgoing supernova shock with regions of increasing pr3 in the stellar mantle. One conclusion is that Type II-L supernovae may occur in mass exchanging binaries very similar to the one that produced SN 1993J, but with slightly larger initial separations and residual hydrogen envelopes (∼1 Mʘ and radius ∼ several AU). The shock interaction, on the other hand, has important implications for the formation of black holes in explosions that are, near peak light, observationally indistinguishable from ordinary Type II-p and lb supernovae.

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