The shape of SN 1993J re-analyzed

Abstract

SN 1993J is one of the best studied Type IIb supernovae. Spectropolarimetric data analyses were published over two decades ago at a time when the field of supernova spectropolarimetry was in its infancy. Here we present a new analysis of the spectropolarimetric data of SN 1993J and an improved estimate of its interstellar polarization (ISP) as well as a critical review of ISP removal techniques employed in the field. The polarization of SN 1993J is found to show significant alignment on the $q-u$ plane, suggesting the presence of a dominant axis and therefore of continuum polarization. We also see strong line polarization features, including $\mathrm{H}\beta$, He\,{\sc i} $\lambda 5876$, $\mathrm{H}\alpha$, He\,{\sc i} $\lambda 6678$, He\,{\sc i} $\lambda 7065$, and high velocity (HV) components of He\,{\sc i} $\lambda 5876$ and $\mathrm{H}\alpha$. SN 1993J is therefore the second example of a stripped envelope supernova, alongside iPTF13bvn, with prominent HV helium polarization features, and the first to show a likely HV \halpha contribution. Overall, we determine that the observed features can be interpreted as the superposition of anisotropically distributed line forming regions over ellipsoidal ejecta. We cannot exclude the possibility of an off-axis energy source within the ejecta. These data demonstrate the rich structures that are inaccessible if solely considering the flux spectra but can be probed by spectropolarimetric observations. In future studies, the new ISP corrected data can be used in conjunction with 3D radiative transfer models to better map the geometry of the ejecta of SN 1993J.

arXiv comment18 pages, 12 figures, Accepted for publication in MNRAS

References in corpus (54)

• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• Progenitors of core-collapse supernovae
• 9286 Stars: An Agglomeration of Stellar Polarization Catalogs
• An Empirical Relation between Sodium Absorption and Dust Extinction
• Spectropolarimetry of Supernovae
• The massive binary companion star to the progenitor of supernova 1993J
• The death of massive stars - II. Observational constraints on the progenitors of type Ibc supernovae
• A non-spherical core in the explosion of supernova SN 2004dj
• Evidence for Asphericity in a Subluminous Type Ia Supernova: Spectropolarimetry of SN 1999by
• Analysis of the Flux and Polarization Spectra of the Type Ia Supernova SN 2001el: Exploring the Geometry of the High-velocity Ejecta
• Error Analysis for Dual-Beam Optical Linear Polarimetry
• Is it Round? Spectropolarimetry of the Type II-P Supernova 1999em
• Optical Spectroscopy of Supernova 1993J During Its First 2500 Days
• Analyzing the Largest Spectroscopic Dataset of Stripped Supernovae to Improve Their Identifications and Constrain Their Progenitors
• Evidence for Spectropolarimetric Diversity in Type Ia Supernovae
• The Disappearance of the Progenitors of Supernovae 1993J and 2003gd
• Polarimetry of the Type Ia Supernova SN 1996X
• Spectropolarimetry of the Type Ic SN 2002ap in M74: More Evidence for Asymmetric Core Collapse
• Spectropolarimetry of the Peculiar Type Ia SN 2005hk
• Comparative Direct Analysis of Spectra of Type Ia Supernovae. I. SN 1994D
• Optical Spectropolarimetry of SN 2002ap: High Velocity Asymmetric Explosion
• VLT Spectropolarimetry of the fast expanding Type Ia SN2006X
• Spectropolarimetry of superluminous supernovae: insight into their geometry
• Spectropolarimetry of the Type Ib/c SN 2005bf
• Asymmetries in the Type IIn SN2010jl
• Photospheric-Phase Spectropolarimetry and Nebular-Phase Spectroscopy of the Peculiar Type Ic Supernova 2002ap
• Analysis of the Polarization and Flux Spectra of SN1993J
• Linear spectropolarimetry of 35 Type Ia Supernovae with VLT/FORS: An analysis of the Si II line polarization
• Light curve and spectral evolution of the Type IIb SN 2011fu
• The Transitional Stripped-Envelope SN 2008ax: Spectral Evolution and Evidence for Large Asphericity
• The Early Asymmetries of Supernova 2008D / XRF 080109
• Properties of extragalactic dust inferred from linear polarimetry of Type Ia Supernovae
• Spectropolarimetry of the Type IIb Supernova 2001ig
• VLT Spectropolarimetry of the Type Ia SN2005ke - A step towards understanding subluminous events
• Probing the Geometry and Circumstellar Environment of SN 1993J in M81
• Spectropolarimetry of the Type Ia Supernova 2012fr
• Spectropolarimetry of the Unique Type Ib Supernova 2005bf: Larger Asymmetry Revealed by Later-Phase Data
• Three-Dimensional Explosion Geometry of Stripped-Envelope Core-Collapse Supernovae. II. Modelling of Polarization
• Evidence for Extremely High Dust Polarization Efficiency in NGC 3184
• Direct Analysis of Spectra of the Peculiar Type Ia Supernova 2000cx
• Supernovae from massive stars with extended tenuous envelopes
• The evolution of the 3D shape of the broad-lined type Ic SN 2014ad
• Comparative Direct Analysis of Type Ia Supernova Spectra. III. Premaximum
• Spectropolarimetry of the Type Ib Supernova iPTF 13bvn: Revealing the complex explosion geometry of a stripped-envelope core-collapse supernova
• Spectropolarimetry of SN 2011dh in M51: geometric insights on a Type IIb supernova progenitor and explosion
• Common continuum polarization properties: a possible link between proto-planetary nebulae and Type Ia Supernovae progenitors
• Optical Photometry of SN 1993J: Years 1995 to 2003
• Polarization of SN 1987A Revisited
• The 3D shape of Type IIb SN 2011hs
• Spectropolarimetry of Galactic stars with anomalous extinction sightlines
• Mapping Circumstellar Matter with Polarized Light - The Case of Supernova 2014J in M82
• Spectropolarimetry of the Type IIb SN 2008aq
• Probing the rotational velocity of Galactic WO stars with spectropolarimetry
• Spectropolarimetry of stripped envelope core collapse supernovae and their progenitors

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