Explosion of a massive, He-rich star at z = 0.16
Date Issued
2015
Author(s)
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Nicholl, M.
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Valenti, S.
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Monard, L. A. G.
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Riello, M.
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Description
We are grateful to M. Hamuy, G. Pignata and J. B. Vanssay for the SN 2002hy data. NER acknowledges the support from the European Union Seventh Framework Programme (FP7/2007–13) under grant agreement no. 267251 ‘Astronomy Fellowships in Italy’ (AstroFIt). NER, AP, SB and MT are partially supported by the PRIN-INAF 2014 with the project ‘Transient Universe: unveiling new types of stellar explosions with PESSTO’. This work is based on observations made with ESO Telescopes at the La Silla and Paranal Observatories under programme ID 064.H-0390, 067.A-0497, 068.A-0443, 068.D-0273, 069.A-0312 and 070.D-0721. This work has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.
Abstract
We present spectroscopic and photometric data of the peculiar SN 2001gh, discovered by the Southern inTermediate Redshift ESO Supernova Search at a redshift z = 0.16. SN 2001gh has relatively high luminosity at maximum (MB = -18.55 mag), while the light curve shows a broad peak. An early-time spectrum shows an almost featureless, blue continuum with a few weak and shallow P-Cygni lines that we attribute to He I. He I lines remain the only spectral features visible in a subsequent spectrum, obtained one month later. A remarkable property of SN 2001gh is the lack of significant spectral evolution over the temporal window of nearly one month separating the two spectra. In order to explain the properties of SN 2001gh, three powering mechanism are explored, including radioactive decays of a moderately large amount of 56Ni, magnetar spin-down, and interaction of SN ejecta with circumstellar medium. We favour the latter scenario, with a SN Ib wrapped in a dense, circumstellar shell. The fact that no models provide an excellent fit with observations, confirms the troublesome interpretation of the nature of SN 2001gh. A rate estimate for SN 2001gh-like event is also provided, confirming the intrinsic rarity of these objects.
Volume
451
Issue
3
Start page
3151
Issn Identifier
0035-8711
Ads BibCode
2015MNRAS.451.3151E
Rights
open.access
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