scholarly journals LSQ13ddu: a rapidly evolving stripped-envelope supernova with early circumstellar interaction signatures

2020 ◽  
Vol 492 (2) ◽  
pp. 2208-2228 ◽  
Author(s):  
Peter Clark ◽  
Kate Maguire ◽  
Cosimo Inserra ◽  
Simon Prentice ◽  
Stephen J Smartt ◽  
...  
Keyword(s):  
Light Curve ◽  
Time Behaviour ◽  
Rapid Rise ◽  
Circumstellar Material ◽  
Luminous Blue Variables ◽  
Decay Component ◽  
Wind Velocities

ABSTRACT This paper describes the rapidly evolving and unusual supernova LSQ13ddu, discovered by the La Silla-QUEST survey. LSQ13ddu displayed a rapid rise of just 4.8 ± 0.9 d to reach a peak brightness of −19.70 ± 0.02 mag in the LSQgr band. Early spectra of LSQ13ddu showed the presence of weak and narrow $\mathrm{ He}\, {\small I}$ features arising from interaction with circumstellar material (CSM). These interaction signatures weakened quickly, with broad features consistent with those seen in stripped-envelope SNe becoming dominant around two weeks after maximum. The narrow $\mathrm{ He}\, {\small I}$ velocities are consistent with the wind velocities of luminous blue variables but its spectra lack the typically seen hydrogen features. The fast and bright early light curve is inconsistent with radioactive 56Ni powering but can be explained through a combination of CSM interaction and an underlying 56Ni decay component that dominates the later time behaviour of LSQ13ddu. Based on the strength of the underlying broad features, LSQ13ddu appears deficient in He compared to standard SNe Ib.

scholarly journals Evolutionary Changes in LUMINOUS STARS

1998 ◽  
Vol 11 (1) ◽  
pp. 346-346
Author(s):  
E. Zsldos
Keyword(s):  
Light Curve ◽  
19Th Century ◽  
Stellar Evolution ◽  
Colour Change ◽  
Light Curves ◽  
Appreciable Change ◽  
Luminous Blue Variables ◽  
Secular Changes ◽  
Evolutionary Changes ◽  
The 19Th Century

The light curves of luminous stars often show spectacular secular changes which can be connected to stellar evolution. Such events are, e.g. the outbursts of P Cygni in the 17th century and 77 Carinae in the last century. Both stars belong to the Luminous Blue Variables, but these changes are not restricted to blue stars. The light curve of HR 8752 (V509 Cassiopeiae) shows a certain similarity to that of the former two stars. When it was first catalogued in the middle of the 19th century, it had been a 6m star. During 100 years the star showed a secular brightening of lm. A similar yellow hypergiant, p Cassiopeiae produced at least two outbursts this century, though both have smaller amplitudes than it is in the case of the LBVs. Moreover, these yellow variables also have an apparently secular colour change: the B − V colour of HR 8752 is decreasing while that of ρ Cassiopeiae is increasing. In both cases evolutionary changes are possible but one cannot exclude other causes. Besides these well studied stars there are several other yellow hypergiants with promising light curves. One of the most interesting cases seems to be R Puppis, which was discovered to be variable in the last century, but then did not show any appreciable change in the following 70-80 years. In the late 1970s, however, it began to vary once more.

scholarly journals The Long-Term Variability of Luminous Blue Variables

1999 ◽  
Vol 169 ◽  
pp. 243-248
Author(s):  
Roberta M. Humphreys
Keyword(s):  
Light Curve ◽  
Luminous Blue Variables ◽  
Second Peak ◽  
Hr Diagram

AbstractThe stars known as Luminous Blue Variables include two very distinctive subgroups - the S Dor-type variables which basically define what we call an LBV and the much rarer ‘giant eruption’ LBV’s which include famous stars like η Car and P Cyg. The distinctive characteristics and long term variability of these two groups is reviewed. The lesser 1890 eruption of η Car is shown to have been much more significant than previously believed and resembles the second peak seen in the historic light curve of P Cyg. Because so many, if not all, stars in certain parts of the HR diagram appear to be luminous, blue, and variable, I suggest returning to our previous designation - S Dor variables and η Car variables for these two important groups of stars.

Early Blue Excess from the Type Ia Supernova 2017cbv

2017 ◽  
Vol 14 (S339) ◽  
pp. 47-49
Author(s):  
G. Hosseinzadeh
Keyword(s):  
Light Curve ◽  
Standard Type ◽  
Circumstellar Material ◽  
Type Ia Supernova ◽  
Unusual Distribution ◽  
Photometric Observations ◽  
Type Ia ◽  
Optical Light Curve ◽  
Ia Supernovae

AbstractThis paper presented very early, high-cadence photometric observations of the nearby Type Ia SN 2017cbv. The light-curve is unique in that during the first five days of observations it has a blue bump in the U, B, and g bands which is clearly resolved by virtue of our photometric cadence of 5.7 hr during that time span. We modelled the light-curve as the combination of an early shock of the supernova ejecta against a non-degenerate companion star plus a standard Type Ia supernova component. Our best-fit model suggested the presence of a subgiant star 56 R⊙ from the exploding white dwarf, although that number is highly model-dependent. While the model matches the optical light-curve well, it over-predicts the flux expected in the ultraviolet bands. That may indicate that the shock is not a blackbody, perhaps because of line blanketing in the UV. Alternatively, it could point to another physical explanation for the optical blue bump, such as interaction with circumstellar material or an unusual distribution of the element Ni. Early optical spectra of SN 2017cbv show strong carbon absorption as far as day –13 with respect to maximum light, suggesting that the progenitor system contained a significant amount of unburnt material. These results for SN 2017cbv illustrate the power of early discovery and intense follow-up of nearby supernovæ for resolving standing questions about the progenitor systems and explosion mechanisms of Type Ia supernovæ.

scholarly journals A type Ia supernova at the heart of superluminous transient SN 2006gy

Science ◽  
2020 ◽  
Vol 367 (6476) ◽  
pp. 415-418 ◽  
Author(s):  
Anders Jerkstrand ◽  
Keiichi Maeda ◽  
Koji S. Kawabata
Keyword(s):  
Binary System ◽  
Light Curve ◽  
Supernova Explosion ◽  
Large Mass ◽  
Late Time ◽  
Standard Type ◽  
Circumstellar Material ◽  
Common Envelope ◽  
Type Ia Supernova ◽  
Type Ia

Superluminous supernovae radiate up to 100 times more energy than normal supernovae. The origin of this energy and the nature of the stellar progenitors of these transients are poorly understood. We identify neutral iron lines in the spectrum of one such supernova, SN 2006gy, and show that they require a large mass of iron (≳0.3 solar masses) expanding at 1500 kilometers per second. By modeling a standard type Ia supernova hitting a shell of circumstellar material, we produce a light curve and late-time iron-dominated spectrum that match the observations of SN 2006gy. In such a scenario, common envelope evolution of a progenitor binary system can synchronize envelope ejection and supernova explosion and may explain these bright transients.

scholarly journals On the Gaia DR2 distances for Galactic luminous blue variables

2019 ◽  
Vol 488 (2) ◽  
pp. 1760-1778 ◽  
Author(s):  
Nathan Smith ◽  
Mojgan Aghakhanloo ◽  
Jeremiah W Murphy ◽  
Maria R Drout ◽  
Keivan G Stassun ◽  
...  
Keyword(s):  
Main Sequence ◽  
Mass Range ◽  
Instability Strip ◽  
Single Star ◽  
Circumstellar Material ◽  
Luminous Blue Variables ◽  
Binary Evolution ◽  
Lower Luminosity ◽  
Gaia Dr2 ◽  
Wide Swath

ABSTRACT We examine parallaxes and distances for Galactic luminous blue variables (LBVs) in the Gaia second data release (DR2). The sample includes 11 LBVs and 14 LBV candidates. For about half of the sample, DR2 distances are either similar to commonly adopted literature values, or the DR2 values have large uncertainties. For the rest, reliable DR2 distances differ significantly from values in the literature, and in most cases the Gaia DR2 distance is smaller. Two key results are that the S Doradus instability strip may not be as clearly defined as previously thought, and that there exists a population of LBVs at relatively low luminosities. LBVs seem to occupy a wide swath from the end of the main sequence at the blue edge to ∼8000 K at the red side, with a spread in luminosity reaching as low as log(L/L⊙) ≈ 4.5. The lower-luminosity group corresponds to effective single-star initial masses of 10–25 M⊙, and includes objects that have been considered as confirmed LBVs. We discuss implications for LBVs including (1) their instability and origin in binary evolution, (2) connections to some supernova (SN) impostors such as the class of SN 2008S-like objects, and (3) LBVs that may be progenitors of SNe with dense circumstellar material across a wide initial mass range. Although some of the Gaia DR2 distances for LBVs have large uncertainty, this represents the most direct and consistent set of Galactic LBV distance estimates available in the literature.

scholarly journals Progenitors of early-time interacting supernovae

2020 ◽  
Vol 496 (2) ◽  
pp. 1325-1342 ◽  
Author(s):  
Ioana Boian ◽  
Jose H Groh
Keyword(s):  
Mass Loss ◽  
Large Scale ◽  
Massive Stars ◽  
Early Time ◽  
High Mass ◽  
Single Star ◽  
Circumstellar Material ◽  
Wide Range ◽  
Wind Velocities ◽  
Loss Rates

ABSTRACT We compute an extensive set of early-time spectra of supernovae interacting with circumstellar material using the radiative transfer code cmfgen. Our models are applicable to events observed from 1 to a few days after explosion. Using these models, we constrain the progenitor and explosion properties of a sample of 17 observed interacting supernovae at early times. Because massive stars have strong mass-loss, these spectra provide valuable information about supernova progenitors, such as mass-loss rates, wind velocities, and surface abundances. We show that these events span a wide range of explosion and progenitor properties, exhibiting supernova luminosities in the 108 to 1012 L⊙ range, temperatures from 10 000 to 60 000 K, progenitor mass-loss rates from a few 10−4 up to 1 M⊙ yr−1, wind velocities from 100 to 800 km s−1, and surface abundances from solar-like to H-depleted. Our results suggest that many progenitors of supernovae interacting with circumstellar material have significantly increased mass-loss before explosion compared to what massive stars show during the rest of their lifetimes. We also infer a lack of correlation between surface abundances and mass-loss rates. This may point to the pre-explosion mass-loss mechanism being independent of stellar mass. We find that the majority of these events have CNO-processed surface abundances. In the single star scenario this points to a preference towards high-mass RSGs as progenitors of interacting SNe, while binary evolution could impact this conclusion. Our models are publicly available and readily applicable to analyse results from ongoing and future large-scale surveys such as the Zwicky Transient Factory.

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 Broad-lined type Ic supernova iPTF16asu: A challenge to all popular models

2019 ◽  
Vol 489 (1) ◽  
pp. 1110-1119 ◽  
Author(s):  
L J Wang ◽  
X F Wang ◽  
Z Cano ◽  
S Q Wang ◽  
L D Liu ◽  
...  
Keyword(s):  
Light Curve ◽  
Rest Frame ◽  
Mass Loss Rate ◽  
Natural Extension ◽  
Late Time ◽  
Rapid Rise ◽  
Model Interaction ◽  
Cascade Decay ◽  
Radioactive Heating ◽  
Very High

ABSTRACT It is well known that ordinary supernovae (SNe) are powered by 56Ni cascade decay. Broad-lined type Ic SNe (SNe Ic-BL) are a subclass of SNe that are not all exclusively powered by 56Ni decay. It was suggested that some SNe Ic-BL are powered by magnetar spin-down. iPTF16asu is a peculiar broad-lined type Ic supernova discovered by the intermediate Palomar Transient Factory. With a rest-frame rise time of only 4 d, iPTF16asu challenges the existing popular models, for example, the radioactive heating (56Ni-only) and the magnetar +56Ni models. Here we show that this rapid rise could be attributed to interaction between the SN ejecta and a pre-existing circumstellar medium ejected by the progenitor during its final stages of evolution, while the late-time light curve can be better explained by energy input from a rapidly spinning magnetar. This model is a natural extension to the previous magnetar model. The mass-loss rate of the progenitor and ejecta mass are consistent with a progenitor that experienced a common envelope evolution in a binary. An alternative model for the early rapid rise of the light curve is the cooling of a shock propagating into an extended envelope of the progenitor. It is difficult at this stage to tell which model (interaction+magnetar + 56Ni or cooling+magnetar + 56Ni) is better for iPTF16asu. However, it is worth noting that the inferred envelope mass in the cooling+magnetar + 56Ni is very high.

scholarly journals Unraveling the variability of σ Ori E

2014 ◽  
Vol 9 (S307) ◽  
pp. 348-352
Author(s):  
M. E. Oksala ◽  
O. Kochukhov ◽  
J. Krtička ◽  
M. Prvák ◽  
Z. Mikulášek
Keyword(s):  
Magnetic Field ◽  
Light Curve ◽  
Elemental Abundance ◽  
Doppler Imaging ◽  
Thermodynamical Equilibrium ◽  
Circumstellar Material ◽  
Magnetic Field Topology ◽  
Non Local ◽  
Optical Brightness ◽  
Physical Phenomena

Abstractσ Ori E (HD 37479) is the prototypical helium-strong star shown to harbor a strong magnetic field, as well as a magnetosphere consisting of two clouds of plasma. The observed optical (ubvy) light curve of σ Ori E is dominated by eclipse features due to circumstellar material, however, there remain additional features unexplained by the Rigidly Rotating Magnetosphere (RRM) model of Townsend & Owocki (2005). Using the technique of magnetic Doppler imaging (MDI), spectropolarimetric observations of σ Ori E are used to produce maps of both the magnetic field topology and various elemental abundance distributions. We also present an analysis utilizing these computed MDI maps in conjunction with non-local thermodynamical equilibrium TLUSTY models to study the optical brightness variability of this star arising from surface inhomogeneities. It has been suggested that this physical phenomena may be responsible for the light curve inconsistencies between the model and observations.

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.

Sign in / Sign up

Export Citation Format

Share Document