The 3D shape of Type IIb SN 2011hs. (arXiv:1901.07562v1 [astro-ph.SR])
<a href="http://arxiv.org/find/astro-ph/1/au:+Stevance_H/0/1/0/all/0/1">H. F. Stevance</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Maund_J/0/1/0/all/0/1">J.R. Maund</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baade_D/0/1/0/all/0/1">D. Baade</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bruten_J/0/1/0/all/0/1">J. Bruten</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Cikota_A/0/1/0/all/0/1">A. Cikota</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hoflich_P/0/1/0/all/0/1">P. Höflich</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wang_L/0/1/0/all/0/1">L. Wang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wheeler_J/0/1/0/all/0/1">J.C. Wheeler</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Clocchiatti_A/0/1/0/all/0/1">A. Clocchiatti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Spyromilio_J/0/1/0/all/0/1">J. Spyromilio</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Patat_F/0/1/0/all/0/1">F. Patat</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Yang_Y/0/1/0/all/0/1">Y. Yang</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Crowther_P/0/1/0/all/0/1">P. Crowther</a>
We observed seven epochs of spectropolarimetry in optical wavelengths for the
Type IIb SN 2011hs, ranging from -3 to +40 days with respect to V -band
maximum. A high degree of interstellar polarization was detected (up to ~3
percent), with a peak lying blueward of 4500A. Similar behaviours have been
seen in some Type Ia SNe, but had never been observed in a Type IIb. We find
that it is most likely the result of a relative enhancement of small silicate
grains in the vicinity of the SN. Significant intrinsic continuum polarization
was recovered at -3 and +2 days (p = 0.55 +- 0.12 percent and p = 0.75 +-
0.11 percent, respectively). We discuss the change of the polarization angle
across spectral lines and in the continuum as diagnostics for the 3D structure
of the ejecta. We see a gradual rotation by about -50 degree in the continuum
polarization angle between -2 and +18 days after V – band maximum. A similar
rotation in He I {lambda}5876, H{alpha} and the Ca II infrared triplet seems
to indicate a strong influence of the global geometry on the line polarization
features. The differences in the evolution of their respective loops on the
Stokes q – u plane suggest that line specific geometries are also being probed.
Possible interpretations are discussed and placed in the context of literature.
We find that the spectropolarimetry of SN 2011hs is most similar to that of SN
2011dh, albeit with notable differences.
We observed seven epochs of spectropolarimetry in optical wavelengths for the
Type IIb SN 2011hs, ranging from -3 to +40 days with respect to V -band
maximum. A high degree of interstellar polarization was detected (up to ~3
percent), with a peak lying blueward of 4500A. Similar behaviours have been
seen in some Type Ia SNe, but had never been observed in a Type IIb. We find
that it is most likely the result of a relative enhancement of small silicate
grains in the vicinity of the SN. Significant intrinsic continuum polarization
was recovered at -3 and +2 days (p = 0.55 +- 0.12 percent and p = 0.75 +-
0.11 percent, respectively). We discuss the change of the polarization angle
across spectral lines and in the continuum as diagnostics for the 3D structure
of the ejecta. We see a gradual rotation by about -50 degree in the continuum
polarization angle between -2 and +18 days after V – band maximum. A similar
rotation in He I {lambda}5876, H{alpha} and the Ca II infrared triplet seems
to indicate a strong influence of the global geometry on the line polarization
features. The differences in the evolution of their respective loops on the
Stokes q – u plane suggest that line specific geometries are also being probed.
Possible interpretations are discussed and placed in the context of literature.
We find that the spectropolarimetry of SN 2011hs is most similar to that of SN
2011dh, albeit with notable differences.
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