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تسجيل مستخدم جديدSN2002bu -- Another SN2008S-like Transient
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D. M. Szczygiel
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We observed SN2002bu in the near-IR with the Hubble Space Telescope, the mid-IR with the Spitzer Space Telescope and in X-rays with Swift 10 years after the explosion. If the faint L_Hsim100 Lsun HST near-IR source at the transient position is the near-IR counterpart of SN2002bu, then the source has dramatically faded between 2004 and 2012, from Lsim10^6.0 Lsun to Lsim10^4.5 Lsun. It is still heavily obscured, tau_Vsim5 in graphitic dust models, with almost all the energy radiated in the mid-IR. The radius of the dust emission is increasing as Rsimt^(0.7+/-0.4) and the optical depth is dropping as tau_Vsimt^(-1.3+/-0.4). The evolution expected for an expanding shell of material, tau_Vsim1/t^2, is ruled out at approximately 2 sigma while the tau_Vsimt^(-0.8) to t^(-1) optical depth scaling for a shock passing through a pre-existing wind is consistent with the data. If the near-IR source is a chance superposition, the present day source can be moderately more luminous, significantly more obscured and evolving more slowly. While we failed to detect X-ray emission, the X-ray flux limits are consistent with the present day emissions being powered by an expanding shock wave. SN2002bu is clearly a member of the SN2008S class of transients, but continued monitoring of the evolution of the spectral energy distribution is needed to conclusively determine the nature of the transient.
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