scholarly journals FLASH SPECTROSCOPY: EMISSION LINES FROM THE IONIZED CIRCUMSTELLAR MATERIAL AROUND <10-DAY-OLD TYPE II SUPERNOVAE

2016 ◽  
Vol 818 (1) ◽  
pp. 3 ◽  
Author(s):  
D. Khazov ◽  
O. Yaron ◽  
A. Gal-Yam ◽  
I. Manulis ◽  
A. Rubin ◽  
...  
Keyword(s):  
Emission Lines ◽  
Type Ii ◽  
Circumstellar Material ◽  
Flash Spectroscopy

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 Luminous Type II supernovae for their low expansion velocities

2020 ◽  
Vol 494 (4) ◽  
pp. 5882-5901 ◽  
Author(s):  
Ó Rodríguez ◽  
G Pignata ◽  
J P Anderson ◽  
T J Moriya ◽  
A Clocchiatti ◽  
...  
Keyword(s):  
Near Infrared ◽  
Current Data ◽  
Type Ii ◽  
Data Set ◽  
Circumstellar Material ◽  
V Band ◽  
Dominant Component ◽  
Absolute Magnitudes ◽  
Using Data ◽  
Early Interaction

ABSTRACT We present optical and near-infrared data of three Type II supernovae (SNe II), SN 2008bm, SN 2009aj, and SN 2009au. These SNe display the following common characteristics: signs of early interaction of the ejecta with circumstellar material (CSM), blue B − V colours, weakness of metal lines, low expansion velocities, and V-band absolute magnitudes 2–3 mag brighter than those expected for normal SNe II based on their expansion velocities. Two more SNe reported in the literature (SN 1983K and LSQ13fn) share properties similar to our sample. Analysing this set of five SNe II, which are luminous for their low expansion velocities (LLEV), we find that their properties can be reproduced assuming ejecta–CSM interaction that lasts between 4 and 11 weeks post-explosion. The contribution of this interaction to the radiation field seems to be the dominant component determining the observed weakness of metal lines in the spectra rather than the progenitor metallicity. Based on hydrodynamic simulations, we find that the interaction of the ejecta with a CSM of ∼3.6 M⊙ can reproduce the light curves and expansion velocities of SN 2009aj. Using data collected by the Chilean Automatic Supernova Search, we estimate an upper limit for the LLEV SNe II fraction to be 2–4 per cent of all normal SNe II. With the current data set, it is not clear whether the LLEV events are a separated class of SNe II with a different progenitor system, or whether they are the extreme of a continuum mediated by CSM interaction with the rest of the normal SN II population.

scholarly journals Late-time Spectral Observations of Type IIP Supernovae

2015 ◽  
Vol 11 (A29B) ◽  
pp. 472-472
Author(s):  
Jeffrey M. Silverman ◽  
Stephanie Pickett ◽  
J. Craig Wheeler ◽  
Alexei V. Filippenko
Keyword(s):  
Temporal Evolution ◽  
Optical Spectra ◽  
Photometric Data ◽  
Emission Lines ◽  
Late Time ◽  
Type Ii ◽  
Insight Into

We are analysing late-time (older than about 150 d past explosion) optical spectra of Type II-Plateau (IIP) supernovae (SNe), which are H-rich SNe that come from red supergiant (RSG) progenitors. The dataset includes nearly 100 spectra of about 40 objects, making this the largest sample of SN IIP nebular spectra ever investigated. Quantitative criteria from within the spectra themselves are employed to determine if an observation is truly nebular, and thus should be included in the study. We present the temporal evolution of the fluxes, shapes, and velocities of various emission lines (see, for example, Fig. 1). These measured values are also compared to photometric data in order to search for correlations that can allow us to gain insight into the diversity of RSG progenitors and learn more about the details of the explosion itself.

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 The Evolution of Ultraviolet Emission Lines From Circumstellar Material Surrounding SN 1987A

1997 ◽  
Vol 477 (2) ◽  
pp. 848-864 ◽  
Author(s):  
George Sonneborn ◽  
Claes Fransson ◽  
Peter Lundqvist ◽  
Angelo Cassatella ◽  
Roberto Gilmozzi ◽  
...  
Keyword(s):  
Emission Lines ◽  
Ultraviolet Emission ◽  
Circumstellar Material ◽  
Sn 1987A

scholarly journals Lα Radiation and CaII Ionization in the TYPE II Supernovae at Late Times

1988 ◽  
Vol 108 ◽  
pp. 415-416
Author(s):  
Nikolai N. Chugai
Keyword(s):  
Emission Lines ◽  
Type Ii ◽  
Order Of Magnitude

AbstractThe ionization of CaII by the Lα quanta in the envelope of the type II supernova 1970g on 270th day is considered. The ratio CaII/CaIII is found to be very low (<0.1). This results in the low theoretical intensities of the CaII emission lines; they are at least an order of magnitude weaker than the observed ones. The implications are discussed.

scholarly journals Photometric and spectroscopic diversity of Type II supernovae

2019 ◽  
Vol 631 ◽  
pp. A8 ◽  
Author(s):  
Desmond John Hillier ◽  
Luc Dessart
Keyword(s):  
Stellar Evolution ◽  
Early Time ◽  
Light Curves ◽  
Type Ii ◽  
Line Profiles ◽  
Circumstellar Material ◽  
Spatially Extended ◽  
Line Widths ◽  
Optical Brightness ◽  
Optical Color

Hydrogen-rich (Type II) supernovae (SNe) exhibit considerable photometric and spectroscopic diversity. Extending previous work that focused exclusively on photometry, we simultaneously model the multi-band light curves and optical spectra of Type II SNe using red supergiant (RSG) progenitors that are characterized by their H-rich envelope masses or the mass and extent of an enshrouding cocoon at the star’s surface. Reducing the H-rich envelope mass yields faster declining light curves, a shorter duration of the photospheric phase, and broader line profiles at early times. However, there is only a modest boost in early-time optical brightness. Increasing the mass of the circumstellar material (CSM) is more effective at boosting the early-time brightness and producing a fast-declining light curve while leaving the duration of the photospheric phase intact. It also makes the optical color bluer, delays the onset of recombination, and can severely reduce the speed of the fastest ejecta material. The early ejecta interaction with CSM is conducive to producing featureless spectra at 10−20 d and a weak or absent Hα absorption during the recombination phase. The slow decliners SNe 1999em, 2012aw, and 2004et can be explained with a 1.2 × 1051 erg explosion in a compact (∼600 R⊙) RSG star from a 15 M⊙ stellar evolution model. A small amount of CSM (<0.2 M⊙) improves the match to the SN photometry before 10 d. With more extended RSG progenitors, models predict lower ejecta kinetic energies, but the SN color stays blue for too long and the spectral line widths are too narrow. The fast decliners SNe 2013ej and 2014G may require 0.5−1.0 M⊙ of CSM, although this depends on the CSM structure. A larger boost to the luminosity (as needed for the fast decliners SNe 1979C or 1998S) requires interaction with a more spatially extended CSM, which might also be detached from the star.

scholarly journals Infrared spectroscopy of Be/X-ray binaries

1994 ◽  
Vol 162 ◽  
pp. 204-205
Author(s):  
C. Everall ◽  
M.J. Coe ◽  
P. Roche ◽  
A. J. Norton ◽  
S. J. Unger
Keyword(s):  
Emission Lines ◽  
Circumstellar Disk ◽  
Density Structure ◽  
X Ray ◽  
Circumstellar Material ◽  
Field Temperature ◽  
Be Star ◽  
Ir Emission ◽  
X Ray Binaries ◽  
Depth Effects

We present infrared spectra of 4 Be/X-ray binaries in the K band, and 4 spectra in the J, H and K bands of 2 more sources. The HI IR emission lines are useful determinators of the conditions in the inner regions of the circumstellar disk about the Be star, due to optical depth effects. These are preliminary results, and hope to be followed up by high resolution echelle spectra, where we wish to estimate the velocity field, temperature and density structure of the circumstellar material.

scholarly journals Multiwavelength observations of the Be-star/X-ray binary EXO2030+375 during outburst

1994 ◽  
Vol 162 ◽  
pp. 206-207
Author(s):  
A.J. Norton ◽  
M.J. Coe ◽  
C. Everall ◽  
P. Roche ◽  
L. Bildsten ◽  
...  
Keyword(s):  
Neutron Star ◽  
Emission Lines ◽  
Be Stars ◽  
Infrared Excess ◽  
X Ray ◽  
Circumstellar Material ◽  
Spin Period ◽  
Be Star ◽  
Star Surface ◽  
X Ray Binaries

EXO2030+375 consists of a neutron star in an eccentric 46 day orbit around a 20th magnitude Be-star companion (Coe et al., 1988; Parmar et al., 1989; Stollberg et al., 1993). The Be-star is thought to be surrounded by a shell/disc of material which is responsible for the infrared excess and Balmer emission lines which are characteristic of Be-stars in general. At periastron, the neutron star passes through this circumstellar material, giving rise to enhanced accretion onto the neutron star surface. As a result of this, the X-ray emission (pulsed at the neutron star spin period of 41.8s) increases dramatically, so producing the transient, outburst behaviour which is commonly seen in Be-star / X-ray binaries.

Sign in / Sign up

Export Citation Format

Share Document