Radio Supernova 1987 A

1992 ◽  
Vol 10 (1) ◽  
pp. 38-40 ◽  
Author(s):  
Lewis Ball ◽  
J.G. Kirk
Keyword(s):  
Shock Wave ◽  
Synchrotron Radiation ◽  
Radio Emission ◽  
Density Jump ◽  
Circumstellar Material ◽  
Sn 1987A

AbstractThe reappearance of radio emission from SN 1987A is discussed. We propose a model involving synchrotron radiation from electrons which are accelerated when the expanding supernova shock wave runs into a density jump in the circumstellar material, and which then expand adiabatically.

AT Monitoring of SNR 1987A

1991 ◽  
Vol 9 (1) ◽  
pp. 108-108
Author(s):  
L. Staveley-Smith ◽  
R. N. Manchester ◽  
M. J. Kesteven
Keyword(s):  
Radio Emission ◽  
High Velocity ◽  
High Sensitivity ◽  
Circumstellar Material ◽  
Sn 1987A ◽  
Upper Limit ◽  
Compact Array

AbstractThe prompt radio emission associated with SN 1987A appeared and disappeared within the space of a few days. The next radio emission is expected as the high velocity ejecta expand into the circumstellar material. The evidence from the timing of the initial UV-flash is that this stage may occur shortly. We have therefore begun to monitor the field around SNR 1987A at high sensitivity with the Australia Telescope Compact Array. At λ6cm, an upper limit to the radio emission of 180μJy has been obtained. Continued observations are planned.

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.

Conditions needed for generation of type II radio emission in the interplanetary space

2021 ◽  
Author(s):  
Immanuel Christopher Jebaraj ◽  
Athanasios Kouloumvakos ◽  
Jasmina Magdalenic ◽  
Alexis Rouillard ◽  
Vratislav Krupar ◽  
...  
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Radio Emission ◽  
Interplanetary Space ◽  
Region Of Interest ◽  
Type Ii ◽  
Radio Observations ◽  
Wave Parameters ◽  
First Results ◽  
Radio Signature

<p>Eruptive events such as Coronal mass ejections (CMEs) and flares cangenerate shock waves. Tracking shock waves and predicting their arrival at Earth is a subject of numerous space weather studies. Ground-based radio observations allow us to locate shock waves in the low corona while space-based radio observations provide us opportunity to track shock waves in the inner heliosphere. We present a case study of CME/flare event, associated shock wave and its radio signature, i.e. type II radio burst.</p><p>In order to analyze the shock wave parameters, we employed a robust paradigm. We reconstructed the shock wave in 3D using multi-viewpoint observations and modelled the evolution of its parameters using a 3D MHD background coronal model produced by the MAS (Magnetohydrodynamics Around a Sphere).</p><p>To map regions on the shock wave surface, possibly associated with the electron acceleration, we combined 3D shock modelling results with the 3D source positions of the type II burst obtained using the radio triangulation technique. We localize the region of interest on the shock surface and examine the shock wave parameters to understand the relationship between the shock wave and the radio event. We analyzed the evolution of the upstream plasma characteristics and shock wave parameters during the full duration of the type II radio emission. First results indicate that shock wave geometry and its relationship with shock strength play an important role in the acceleration of electrons responsible for the generation of type II radio bursts.</p>

scholarly journals Super-Resolution of the Radio Remnant of SN 1987A

1998 ◽  
Vol 164 ◽  
pp. 359-360
Author(s):  
B. M. Gaensler ◽  
A. K. Tzioumis ◽  
R. N. Manchester ◽  
L. Staveley-Smith ◽  
J. E. Reynolds ◽  
...  
Keyword(s):  
Shock Front ◽  
Flux Density ◽  
Super Resolution ◽  
Circumstellar Material ◽  
Sn 1987A

AbstractThe radio remnant of SN 1987A is now of sufficient flux density that super-resolution is possible at 9 GHz. We present a sequence of images from 1992 to 1996 with a resolution of ≈ 0″.5xb, showing the continuing interaction between the expanding shock front and the surrounding axisymmetric circumstellar material.

scholarly journals Peculiar Differences in Radio and X-ray Synchrotron Radiation from Pulsar Wind Nebulae

2004 ◽  
Vol 218 ◽  
pp. 221-224
Author(s):  
John R. Dickel ◽  
Shiya Wang
Keyword(s):  
Synchrotron Radiation ◽  
Radio Emission ◽  
Supernova Remnants ◽  
Crab Nebula ◽  
Pulsar Wind Nebulae ◽  
X Ray ◽  
Pulsar Wind ◽  
The Crab Nebula

Several Crab-type supernova remnants appear to have very bright non-thermal X-ray cores just around the pulsar or expected pulsar. This X-ray brightness is often not matched by a corresponding increase in radio emission. The best example of this phenomenon is in N157B in the LMC. G21.5−0.9 and possibly 3C 58 also show it while the Crab Nebula and 0540−69.3 do not. Some method to enhance the higher energy particles must be present in these objects.

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 An Update on Radio Supernovae

1998 ◽  
Vol 164 ◽  
pp. 357-358 ◽  
Author(s):  
Schuyler D. Van Dyk ◽  
Richard A. Sramek ◽  
Kurt W. Weiler ◽  
Marcos J. Montes ◽  
Nino Panagia
Keyword(s):  
Synchrotron Radiation ◽  
Radio Emission ◽  
Brightness Temperature ◽  
Power Law ◽  
Progress Report ◽  
Light Curves ◽  
High Brightness ◽  
Turn On ◽  
Distance Indicators ◽  
Circumstellar Environment

AbstractThe radio emission from supernovae (SNe) is nonthermal synchrotron radiation of high brightness temperature, with a “turn-on” delay at longer wavelengths, power-law decline after maximum with index β, and spectral index α asymptotically decreasing with time to a final, optically thin value. Radio supernovae (RSNe) are best described by the Chevalier (1982) “mini-shell” model, with modifications by Weiler et al. (1990). RSNe observations provide a valuable probe of the SN circumstellar environment and constraints on progenitor masses. We present a progress report on a number of recent RSNe, as well as on new behavior from RSNe 1979C and 1980K, and on RSNe as potential distance indicators. In particular, we present updated radio light curves for SN 1993J in M81.

scholarly journals Radio Emission from Young Supernova Remnants: Effects of an Inhomogeneous Circumstellar Medium

1988 ◽  
Vol 101 ◽  
pp. 235-238
Author(s):  
John R. Dickel ◽  
Jean A. Eilek ◽  
Eric M. Jones
Keyword(s):  
Magnetic Fields ◽  
Radio Emission ◽  
Supernova Remnants ◽  
Homogeneous Medium ◽  
Shock Acceleration ◽  
Relativistic Electrons ◽  
Circumstellar Material ◽  
Turbulent Dynamo ◽  
Synchotron Radiation ◽  
Hydrodynamic Code

AbstractThe evolution of young supernova remnants has been modeled using a 1-dimensional hydrodynamic code. Turbulent dynamo amplification of magnetic fields and both turbulent and shock acceleration of relativistic electrons have been included macroscopically to produce synchotron radiation. The observed radio morphology cannot be reproduced by expansion into a homogeneous medium; it appears that many small cloudlets must be present in the circumstellar material.

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