Reilly, E., Maund, J.R. orcid.org/0000-0003-0733-7215, Baade, D. et al. (5 more authors) (2017) Spectropolarimetry of the 2012 outburst of SN 2009ip: A bi-polar explosion in a dense, disc-like CSM. Monthly Notices of the Royal Astronomical Society, 470 (2). pp. 1491-1511. ISSN 0035-8711
Abstract
We present a sequence of eight spectropolarimetric observations monitoring the geometric evolution of the late phase of the major 2012 outburst of SN 2009ip. These were acquired with the Focal Reducer and Low Dispersion Spectrograph polarimeter mounted on European Southern Observatory VLT. The continuum was polarized at 0.3-0.8 per cent throughout the observations, showing that the photosphere deviated substantially from spherical symmetry by 10-15 per cent. Significant line polarization is detected for both hydrogen and helium at high velocities. The similarity in the polarized signal between these elements indicates that they form in the same location in the ejecta. The line polarization (p ~ 1-1.5 per cent) at low velocities revealed the presence of a highly aspherical hydrogen- and helium-rich circumstellar medium (CSM). Monte Carlo simulations of the observed polarimetry were performed in an effort to constrain the shape of the CSM. The simulations imply that the polarimetry can be understood within the framework of a disc-like CSM inclined by 14° ± 2° out of the line of sight, obscuring the photosphere only at certain epochs. The varying temporal evolution of polarization at high and low velocities indicated that the fast-moving ejecta expanded with a preferred direction orthogonal to that of the CSM.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | This article has been accepted for publication in Monthly Notices of the Royal Astronomical Society. © 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. All rights reserved. |
Keywords: | techniques: polarimetric; circumstellar matter; stars: mass-loss; supernovae: general; supernovae: individual: SN 2009ip |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Physics and Astronomy (Sheffield) |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 09 Oct 2017 15:19 |
Last Modified: | 09 Oct 2017 15:28 |
Published Version: | https://doi.org/10.1093/mnras/stx1228 |
Status: | Published |
Publisher: | Oxford University Press |
Refereed: | Yes |
Identification Number: | 10.1093/mnras/stx1228 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:122220 |