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http://hdl.handle.net/20.500.12386/30834
Titolo: | Indications of a Si-rich bilateral jet of ejecta in the Vela SNR observed with XMM-Newton | Autori: | García, F. Suárez, A. E. Miceli, Marco BOCCHINO, Fabrizio Combi, J. A. ORLANDO, Salvatore Sasaki, M. |
Data pubblicazione: | 2017 | Rivista: | ASTRONOMY & ASTROPHYSICS | Numero: | 604 | Da pagina:: | L5 | Abstract: | Context. The Vela supernova remnant displays several ejecta, which are fragment-like features protruding beyond the front of its primary blast shock wave. They appear to be "shrapnel", bowshock-shaped relics of the supernova explosion. One of these pieces of shrapnel (A), located in the northeastern edge of the remnant, is peculiar because its X-ray spectrum exhibits a high Si abundance, in contrast to the other observed ejecta fragments, which show enhanced O, Ne, and Mg abundances. <BR /> Aims: In this Letter we present the analysis of another ejecta fragment located opposite to shrapnel A with respect to the center of the shell, in the southwestern boundary of the remnant, named shrapnel G. We aim to fully characterize its X-ray emission to gather new information about the core-collapse supernova explosion mechanism. <BR /> Methods: We thoroughly analyzed a dedicated XMM-Newton observation of shrapnel G by producing background-subtracted and exposure-corrected maps in different energy ranges, which we complemented with a spatially resolved spectral analysis of the X-ray emission. <BR /> Results: The fragment presents a bowshock-like shape with its anti-apex pointing to the center of the remnant. Its X-ray spectrum is best fit by a thermal plasma out of equilibrium of ionization with low O and Fe, roughly solar Ne and Mg, and a significantly high Si abundance, which is required to fit a very clear Si line at 1.85 keV. Its chemical composition and spectral properties are compatible with those of shrapnel A, which is located on the opposite side of the remnant. <BR /> Conclusions: As a consequence of the nucleosynthesis, pieces of Si-rich shrapnel are expected to originate in deeper layers of the progenitor star compared to ejecta with lower-Z elements. A high velocity and density contrast with respect to the surrounding ejecta are necessary to make shrapnel A and G overtake the forward shock. The line connecting shrapnel A and G crosses almost exactly the expansion center of the remnant, strongly suggesting a Si-rich jet-counterjet structure, reminiscent of that observed in the young remnant Cas A. | URI: | http://hdl.handle.net/20.500.12386/30834 | URL: | http://arxiv.org/abs/1707.05215v1 https://www.aanda.org/articles/aa/full_html/2017/08/aa31418-17/aa31418-17.html |
ISSN: | 0004-6361 | DOI: | 10.1051/0004-6361/201731418 | Bibcode ADS: | 2017A&A...604L...5G | Fulltext: | open |
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