scholarly journals Spectral Evolution of the X-Ray Remnant of SN 1987A: A High-resolution Chandra HETG Study

2021 ◽  
Vol 922 (2) ◽  
pp. 140
Author(s):  
Aravind P. Ravi ◽  
Sangwook Park ◽  
Svetozar A. Zhekov ◽  
Marco Miceli ◽  
Salvatore Orlando ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Analysis ◽  
Thermal Conditions ◽  
Line Flux ◽  
Spectral Evolution ◽  
X Ray ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Volume Emission ◽  
Post Shock

Abstract Based on observations with the Chandra X-ray Observatory, we present the latest spectral evolution of the X-ray remnant of SN 1987A (SNR 1987A). We present a high-resolution spectroscopic analysis using our new deep (∼312 ks) Chandra HETG observation taken in 2018 March as well as archival Chandra grating spectroscopic data taken in 2004, 2007, and 2011 with similarly deep exposures (∼170–350 ks). We perform detailed spectral model fits to quantify changing plasma conditions over the last 14 yr. Recent changes in electron temperatures and volume-emission measures suggest that the shocks moving through the inner ring have started interacting with less dense circumstellar material, probably beyond the inner ring. We find significant changes in the X-ray line-flux ratios (among H- and He-like Si and Mg ions) in 2018, consistent with changes in the thermal conditions of the X-ray-emitting plasma that we infer based on the broadband spectral analysis. Post-shock electron temperatures suggested by line-flux ratios are in the range ∼0.8–2.5 keV as of 2018. We do not yet observe any evidence of substantial abundance enhancement, suggesting that the X-ray emission component from the reverse-shocked metal-rich ejecta is not yet significant in the observed X-ray spectrum.

scholarly journals High-resolution spectroscopy of SN 2017hcc and its blueshifted line profiles from post-shock dust formation

2020 ◽  
Vol 499 (3) ◽  
pp. 3544-3562
Author(s):  
Nathan Smith ◽  
Jennifer E Andrews
Keyword(s):  
High Resolution ◽  
Electron Scattering ◽  
Wavelength Dependence ◽  
High Resolution Spectroscopy ◽  
Shock Acceleration ◽  
Dust Formation ◽  
Line Profiles ◽  
Circumstellar Material ◽  
Post Shock ◽  
The Continuum

ABSTRACT SN 2017hcc was remarkable for being a nearby and strongly polarized superluminous Type IIn supernova (SN). We obtained high-resolution Echelle spectra that we combine with other spectra to investigate its line-profile evolution. All epochs reveal narrow P Cygni components from pre-shock circumstellar material (CSM), indicating an axisymmetric outflow from the progenitor of 40–50 km s−1. Broad and intermediate-width components exhibit the classic evolution seen in luminous SNe IIn: symmetric Lorentzian profiles from pre-shock CSM lines broadened by electron scattering at early times, transitioning at late times to multicomponent, irregular profiles coming from the SN ejecta and post-shock shell. As in many SNe IIn, profiles show a progressively increasing blueshift, with a clear flux deficit in red wings of the intermediate and broad velocity components after day 200. This blueshift develops after the continuum luminosity fades, and in the intermediate-width component, persists at late times even after the SN ejecta fade. In SN 2017hcc, the blueshift cannot be explained as occultation by the SN photosphere, pre-shock acceleration of CSM, or a lopsided explosion of CSM. Instead, the blueshift arises from dust formation in the post-shock shell and in the SN ejecta. The effect has a wavelength dependence characteristic of dust, exhibiting an extinction law consistent with large grains. Thus, SN 2017hcc experienced post-shock dust formation and had a mildly bipolar CSM shell, similar to SN 2010jl. Like other superluminous SNe IIn, the progenitor lost around 10 M⊙ due to extreme eruptive mass-loss in the decade before exploding.

scholarly journals Review of Contributions to the Workshop on SN1993J

1996 ◽  
Vol 145 ◽  
pp. 241-276
Author(s):  
J. Craig Wheeler ◽  
Alexei V. Filippenko
Keyword(s):  
Gamma Rays ◽  
Electromagnetic Spectrum ◽  
Type Ii ◽  
Spectral Evolution ◽  
X Ray ◽  
Sn 1987A ◽  
Original Mass

At its peak, SN 1993J was one of the brightest supernovae in this century, and it is being studied more thoroughly than any supernova except SN 1987A. It is proving to be similar to the transition object SN 1987K, which metamorphosed from being a hydrogen-rich Type II near peak to having a hydrogen-deficient nebular phase. SN 1993J has been observed throughout the electromagnetic spectrum and with optical spectropolarimetry. It is interacting with a dense circumstellar nebula and is generating radio and X-ray flux, but it has probably not been detected in gamma rays. The photometric and spectral evolution are consistent with a star of original mass ∼ 15 Mʘ that lost appreciable mass to a binary companion leaving an extended, helium-rich hydrogen envelope of ≲ 0.5 Mʘ and a helium core of ∼ 4 Mʘ. The spectral evolution will put strong constraints on the mixing of 66Ni and other species.

scholarly journals Radio Emission from SN 1987A

1996 ◽  
Vol 145 ◽  
pp. 309-315 ◽  
Author(s):  
L. Staveley-Smith ◽  
R. N. Manchester ◽  
A. K. Tzioumis ◽  
J. E. Reynolds ◽  
D. S. Briggs
Keyword(s):  
Radio Emission ◽  
Radio Observations ◽  
Density Profiles ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Supernova 1987A ◽  
Radio Outburst ◽  
Post Shock ◽  
Two Phases ◽  
Relativistic Particles

We review the first six years of radio observations of Supernova 1987A. The evolution can be divided into two phases: the initial radio outburst which lasted a few weeks, and the period from mid-1990 to the present, during which the radio emission has steadily increased. Both phases can be explained by a small fraction (0.1-0.5%) of the post-shock thermal energy being converted to energy in relativistic particles and magnetic fields, which give rise to synchrotron radiation. The optical depths, densities and density profiles for the pre-shocked circumstellar material are somewhat different for the two phases, but consistent with models of the density structure of the material within the circumstellar ring. New high-resolution radio observations show that the SN shock front is already at about three-quarters of the radius of the circumstellar ring, and that there exists a bright equatorial component of emission aligned with this ring which is probably due to a polar density gradient in the ‘hourglass’ structure.

Structure in the Radio Remnant of Supernova 1987A

1993 ◽  
Vol 10 (4) ◽  
pp. 331-334 ◽  
Author(s):  
L. Staveley-Smith ◽  
R.N. Manchester ◽  
M.J. Kesteven ◽  
A.K. Tzioumis ◽  
J.E.R. Reynolds
Keyword(s):  
Radio Emission ◽  
Expansion Velocity ◽  
Synchrotron Emission ◽  
Low Density ◽  
Radial Expansion ◽  
X Ray ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Supernova 1987A ◽  
Compact Array

AbstractThe radio emission associated with SN 1987A appears to be synchrotron emission resulting from the acceleration of electrons at the interface between the outward moving shock wave and clumps of circumstellar material. The Australia Telescope Compact Array is now able to resolve this region, which has dimensions of ~ arcsec, revealing a slight (10%) asphericity in the distribution of the low density gas within the [OIII] circumstellar ring. Assuming that the radio emission arises from a region just behind the shock front, we deduce a mean radial expansion velocity, from 1987 to 1992, of 29 200 kms. First observed contact of the shock with the [OIII] circumstellar ring could occur as early as mid-1993, depending on the deceleration in the intervening gas. This will probably be closely followed by shock-excited optical lines, a strong X-ray outburst and a further increase in the radio emission.

scholarly journals High Resolution EUV & Soft X-Ray Spectrometers Using Variable Groove Spacings

1984 ◽  
Vol 86 ◽  
pp. 84-87
Author(s):  
M. Lampton ◽  
M.C Hettrick ◽  
S. Bowyer
Keyword(s):  
High Resolution ◽  
Optical System ◽  
Spectroscopic Analysis ◽  
Grazing Incidence ◽  
Focus Beam ◽  
Astrophysical Plasmas ◽  
X Ray ◽  
Stellar Spectroscopy ◽  
Grating Spectrometer ◽  
Reflection Grating

Spectroscopic analysis is a powerful technique for the diagnosis of temperatures and compositions of astrophysical plasmas. The EUV (100–1000Å) and soft x-ray (10–100Å) bands contain hundreds of potentially useful diagnostic lines. Unfortunately, traditional types of grating spectrometer become inefficient or unwieldy when adapted to stellar spectroscopy onboard a spacecraft. At grazing incidence, the required length of a high-resolution plane-grating spectrometer can easily exceed the length of the telescope feeding it. For these reasons, we have systematically explored ways to introduce a reflection grating into the converging beam formed by a given objective optical system ahead of its first focus. A spectrometer of this type results in an optical train no longer than the telescope’s existing prime-focus beam.

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