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Supernova 1987A
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Title: Hard X-ray emission lines from the decay of Ti-44 in the remnant of supernova 1987A
Authors: S. A. Grebenev (1), A. A. Lutovinov (1), S. S. Tsygankov (1, 2, 3, 4), C. Winkler (5) ((1) Space Research Institute, Russian Academy of Sciences, (2) Max-Planck-Institut für Astrophysik, (3) FINCA, University of Turku, (4) Astronomy Division, Department of Physics, University of Oulu, (5) European Space Agency, ESTEC)

It is assumed that the radioactive decay of Ti-44 powers the infrared, optical and UV emission of supernova remnants after the complete decay of Co-56 and Co-57 (the isotopes that dominated the energy balance during the first three to four years after the explosion) until the beginning of active interaction of the ejecta with the surrounding matter. Simulations show that the initial mass of Ti-44 synthesized in core-collapse supernovae is (0.02-2.5) x 10^{-4} solar masses. Hard X-rays and gamma-rays from the decay of this Ti-44 have been unambiguously observed from Cassiopeia A only, leading to the suggestion that the values of the initial mass of Ti-44 near the upper bound of the predictions occur only in exceptional cases. For the remnant of supernova 1987A, an upper limit to the initial mass of Ti-44 of < 10^{-3} solar masses has been obtained from direct X-ray observations, and an estimate of (1-2) x 10^{-4} solar masses has been made from infrared light curves and ultraviolet spectra by complex model-dependent computations. Here we report observations of hard X-rays from the remnant of supernova 1987A in the narrow band containing two direct-escape lines of Ti-44 at 67.9 and 78.4 keV. The measured line fluxes imply that this decay provided sufficient energy to power the remnant at late times. We estimate that the initial mass of Ti-44 was (3.1±0.8) x 10^{-4} solar masses, which is near the upper bound of theoretical predictions.

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Radioactive decay of titanium powers supernova remnant

The first direct detection of radioactive titanium associated with supernova remnant 1987A has been made by ESAs Integral space observatory. The radioactive decay has likely been powering the glowing remnant around the exploded star for the last 20 years.
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RE: (SN) 1987A
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Zoom on Supernova 1987A



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Posts: 130177
Date:
Supernova 1987A
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SN 1987A was a supernova in the outskirts of the Tarantula Nebula in the Large Magellanic Cloud, a nearby dwarf galaxy.
The light from the supernova reached Earth on February 23, 1987.

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Title: The missing compact star of SN1987A: a solid quark star?
Authors: X. W. Liu, J. D. Liang, R. X. Xu, J. L. Han, G. J. Qiao

To investigate the missing compact star of Supernova 1987A, we analysed both the cooling and the heating processes of a possible compact star based on the observational X-ray luminosity upper limit. From the cooling process we found that a solid quark cluster star (Lai & Xu 2011), with harder equation of state than liquid quark star, has heat capacity much smaller than neutron star and would cool quickly below the observational X-ray luminosity upper limit, which can naturally explain the non-detection of a point source (neutron star or quark star) in X-ray band. On the other hand, we considered the heating process from magnetospheric activity and possible accretion and obtained some constraints to the parameters of a possible pulsar. We conclude that a solid quark cluster star can accord with the observational limit in a large and normal parameter space, while a pulsar with short period and strong magnetic field (or with long period and weak field) would has luminosity higher than the limit if the optical depth is not large enough to hide the compact star. We expect that the constraints would be tested if the central compact object in 1987A could be discovered by advanced facilities (e.g., in radio bands) in the future.

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Title: Herschel Detects a Massive Dust Reservoir in Supernova 1987A
Authors: M. Matsuura (1 and 2), E. Dwek (3), M. Meixner (4), M. Otsuka (4), B. Babler (5), M.J. Barlow (1), J. Roman-Duval (4), C. Engelbracht (6), K. Sandstrom (7), M. Lakicevic (8 and 9), J.Th. van Loon (8), G. Sonneborn (3), G.C. Clayton (10), K.S. Long (4), P. Lundqvist (11), T. Nozawa (12), K.D. Gordon (4), S. Hony (13), K. Okumura (13), K.A. Misselt (6), E. Montiel (6), M. Sauvage (13) ((1) P&A, University College London, (2) MSSL, University College London, (3) NASA Goddard Space Flight Center, (4) STScI, (5) University of Wisconsin, (6) University of Arizona, (7) Max Planck Institut fur Astronomie, (8) Keele University, (9) ESO, (10) Louisiana State University, (11) Stockholm University, (12) IPMU, University of Tokyo, (13) CEA)

We report far-infrared and submillimetre observations of Supernova 1987A, the star that exploded on February 23, 1987 in the Large Magellanic Cloud, a galaxy located 160,000 lightyears away. The observations reveal the presence of a population of cold dust grains radiating with a temperature of ~17-23 K at a rate of about 220 solar luminosity. The intensity and spectral energy distribution of the emission suggests a dust mass of ~0.4-0.7 solar mass. The radiation must originate from the SN ejecta and requires the efficient precipitation of all refractory material into dust. Our observations imply that supernovae can produce the large dust masses detected in young galaxies at very high redshifts.

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Title: The remnant of SN1987A revealed at (sub-)mm wavelengths
Authors: Masha Lakicevic (ESO/Keele University), Jacco Th. van Loon (Keele University), Ferdinando Patat (ESO), Lister Staveley-Smith (ICRAR - University of Western Australia), Giovanna Zanardo (ICRAR - University of Western Australia)

Context: Supernova 1987A (SN1987A) exploded in the Large Magellanic Cloud (LMC). Its proximity and rapid evolution makes it a unique case study of the early phases in the development of a supernova remnant. One particular aspect of interest is the possible formation of dust in SN1987A, as SNe could contribute significantly to the dust seen at high redshifts.
Aims: We explore the properties of SN1987A and its circumburst medium as seen at mm and sub-mm wavelengths, bridging the gap between extant radio and infrared (IR) observations of respectively the synchrotron and dust emission. Methods: SN1987A was observed with the Australia Telescope Compact Array (ATCA) at 3.2 mm in July 2005, and with the Atacama Pathfinder EXperiment (APEX) at 0.87 mm in May 2007. We present the images and brightness measurements of SN1987A at these wavelengths for the first time. Results: SN1987A is detected as an unresolved point source of 11.2 ±2.0 mJy at 3.2 mm (5" beam) and 21 ±4 mJy at 0.87 mm (18" beam). These flux densities are in perfect agreement with extrapolations of the powerlaw radio spectrum and modified-blackbody dust emission, respectively. This places limits on the presence of free-free emission, which is similar to the expected free-free emission from the ionised ejecta from SN1987A. Adjacent, fainter emission is observed at 0.87 mm extending ~0.5' towards the south-west. This could be the impact of the supernova progenitor's wind when it was still a red supergiant upon a dense medium.
Conclusions: We have established a continuous spectral energy distribution for the emission from SN1987A and its immediate surroundings, linking the IR and radio data. This places limits on the contribution from ionised plasma. Our sub-mm image reveals complexity in the distribution of cold dust surrounding SN1987A, but leaves room for freshly synthesised dust in the SN ejecta.

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Herschel Helps Solve Mystery of Cosmic Dust Origins

New observations from the infrared Herschel Space Observatory reveal that an exploding star expelled the equivalent of between 160,000 and 230,000 Earth masses of fresh dust. This enormous quantity suggests that exploding stars, called supernovae, are the answer to the long-standing puzzle of what supplied our early universe with dust.
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New Supernova Remnant Lights Up

In 1987, light from an exploding star in a neighbouring galaxy, the Large Magellanic Cloud, reached Earth. Named Supernova 1987A, it was the closest supernova explosion witnessed in almost 400 years, allowing astronomers to study it in unprecedented detail as it evolves.
Today a team of astronomers announced that the supernova debris, which has faded over the years, is brightening. This shows that a different power source has begun to light the debris, and marks the transition from a supernova to a supernova remnant.

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SNR 1987A
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Title: A New Evolutionary Phase of Supernova Remnant 1987A
Authors: Sangwook Park (UT Arlinton), Svetozar A. Zhekov (STRI), David N. Burrows (Penn State), Judith L. Racusin (GSFC), Daniel Dewey (MIT), Richard McCray (Colorado)

We have been monitoring the supernova remnant (SNR) 1987A with {\it Chandra} observations since 1999. Here we report on the latest change in the soft X-ray light curve of SNR 1987A. For the last ~1.5 yr (since day ~8000), the soft X-ray flux has significantly flattened, staying (within uncertainties) at f_{X} ~ 5.7 x 10^{-12} erg cm^{-2} s^{-1} (corresponding to L_{X} ~ 3.6 x 10^{36} erg s^{-1}) in the 0.5--2 keV band. This remarkable change in the recent soft X-ray light curve suggests that the forward shock is now interacting with a decreasing density structure, after interacting with an increasing density gradient over ~10 yr prior to day ~8000. Possibilities may include the case that the shock is now propagating beyond a density peak of the inner ring. We briefly discuss some possible implications on the nature of the progenitor and the future prospects of our  Chandra monitoring observations.

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