Evidence of Asymmetry in SN 2007rt, a Type IIn Supernova - Astrophysics > Solar and Stellar AstrophysicsReport as inadecuate

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Abstract: An optical photometric and spectroscopic analysis of the slowly-evolving TypeIIn SN2007rt is presented, covering a duration of 481 days after discovery. Itsearliest spectrum, taken approximately 100 days after the explosion epoch,indicates the presence of a dense circumstellar medium, with which thesupernova ejecta is interacting. This is supported by the slowly-evolving lightcurve. A notable feature in the spectrum of SN 2007rt is the presence of abroad He I 5875 line, not usually detected in Type IIn supernovae. This mayimply that the progenitor star has a high He-H ratio, having shed a significantportion of its hydrogen shell via mass-loss. An intermediate resolutionspectrum reveals a narrow Halpha P-Cygni profile, the absorption component ofwhich has a width of 128 km-s. This slow velocity suggests that the progenitorof SN 2007rt recently underwent mass-loss with wind speeds comparable to thelower limits of those detected in luminous blue variables. Asymmetries in theline profiles of H and He at early phases bears some resemblance todouble-peaked features observed in a number of Ib-c spectra. These asymmetriesmay be indicative of an asymmetric or bipolar outflow or alternatively dustformation in the fast expanding ejecta. In addition, the late time spectrum, atover 240 days post-explosion, shows clear evidence for the presence of newlyformed dust.

Author: C. Trundle 1, A. Pastorello 1, S. Benetti 2, R. Kotak 1, S. Valenti 1, I. Agnoletto 2, F. Bufano 2, M. Dolci 3, N. Elias-Rosa 4,

Source: https://arxiv.org/

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