The late-time expansion of the ejecta of SN 1987A

Jansen, Rolf A.; Jakobsen, P.

doi:10.1051/0004-6361:20010292

Cited by 6 publications

(5 citation statements)

References 14 publications

(27 reference statements)

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“…There is a growing body of evidence that suggests that the supernova explosions at the end of the life of massive stars are not spherically symmetric events. The most notable evidence was the resolved asymmetric structure of SN 1987A, as observed in late time HST imaging (Jansen & Jakobsen 2001;Larsson et al 2013;Sinnott et al 2013). Complex aspherical morphologies have also been observed in Galactic supernova remnants (SNRs), including that of Cassiopeia A (Fesen et al 2001;Wheeler et al 2008;Milisavljevic & Fesen 2013;Rest et al 2011b).…”

Section: Introductionmentioning

confidence: 93%

Spectropolarimetry of the 2012 outburst of SN 2009ip: a bi-polar explosion in a dense, disc-like CSM

Reilly

Maund

Baade

et al. 2017

Monthly Notices of the Royal Astronomical Society

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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.

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Section: Introductionmentioning

confidence: 93%

Spectropolarimetry of the 2012 outburst of SN 2009ip: a bi-polar explosion in a dense, disc-like CSM

Reilly

Maund

Baade

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…-7 -Recent HST images are able to spatially resolve the ejecta. Figure 1 shows an image taken in the F439W filter on 2000 June 11 (see also Jansen & Jakobsen 2001). The ejecta are obviously elongated at a PA of about 14±5 o .…”

Section: The Supernova Ejectamentioning

confidence: 99%

The Axisymmetric Ejecta of Supernova 1987A

Wang

Wheeler

Höflich

et al. 2002

ApJ

173

153

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Extensive early observations proved that the ejecta of supernova 1987A (SN 1987A) are aspherical. The most important of these early observations include (a) the "Bochum event" that revealed small-scale spectroscopic structure indicating chemical inhomogeneities of the ejecta; (b) spectropolarimetry that showed deviations from spherical symmetry; (c) speckle observations that revealed both the asymmetry of the ejecta and the "mystery spot" manifested as a secondary source off center from the bulk of the supernova ejecta. Fifteen years after the supernova explosion, the Hubble Space Telescope has resolved the rapidly expanding ejecta. The late-time images and spectroscopy provide a geometrical picture that is consistent with early observations and suggests a highly structured, axially symmetric geometry. We present here a new synthesis of the old and new data. We show that the Bochum event, presumably a clump of 56 Ni, and the latetime image, the locus of excitation by 44 Ti, are most naturally accounted for by sharing a common position angle of about 14 o , the same as the mystery spot and early speckle data on the ejecta, and that they are both oriented along the axis of the inner circumstellar ring at 45 o to the plane of the sky. We also demonstrate that the polarization represents a prolate geometry with the same position angle and axis as the early speckle data and the late-time image and hence that the geometry has been fixed in time and throughout the ejecta. The Bochum event and the Doppler kinematics of the [Ca II]/[O II] emission in spatially resolved HST spectra of the ejecta can be consistently integrated into this geometry. The radioactive clump is deduced to fall approximately along the axis of the inner circumstellar ring and therefore to be redshifted in the North whereas the [Ca II]/[O II] 7300Å emission is redshifted in the South. We present a jet-induced model for the explosion and argue that such a model can account for many of -3the observed asymmetries. In the jet models, the oxygen and calcium are not expected to be distributed along the jet, but primarily in an expanding torus that shares the plane and northern blue shift of the inner circumstellar ring.

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“…In recent years it has become clear that many if not all supernova (SN) explosions are inherently aspherical processes, whether they arise from thermonuclear (Reinecke, Hillebrandt, & Niemeyer 2002;Gamezo, Khokhlov, & Oran 2005;Kozma 2005) or core-collapse (Burrows et al 2006;Maeda, Mazzali, & Nomoto 2006;Matt, Frank, & Blackman 2006) scenarios. Observational indications of deviation from spherical symmetry in the geometry of SN ejecta include the elongated debris cloud and complex ring structure of SN 1987A (e.g., Wang & Hu 1994;Wang et al 2002;Jansen & Jakobsen 2001), asymmetric structures and velocities in SN remnants (e.g., Fesen et al 2006;Hwang et al 2004), emission line profiles that suggest bipolar ejecta structures (Chugai et al 2005;Taubenberger et al 2006), high-velocity absorption lines in SN spectra (Mazzali et al 2005), and net polarization of the continuum light (e.g., Wang et al 1996;Leonard & Filippenko 2001;Wang et al 2001;Leonard et al 2006;Pereyra et al 2006). In addition to continuum polarization, which points to global asymmetries, line polarization features can provide specific clues to the nature of SN ejecta and their surrounding circumstellar material (CSM; Leonard et al 2000a;Kawabata et al 2002;Kasen et al 2003;Wang et al 2003a,b;Wang et al 2004;Filippenko & Leonard 2004;Chornock et al 2006;.…”

Section: Introductionmentioning

confidence: 99%

The Dual‐Axis Circumstellar Environment of the Type IIn Supernova 1997eg

Hoffman

Leonard

Chornock

et al. 2008

Astrophysical Journal

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We present multi-epoch spectral and spectropolarimetric observations of the Type IIn supernova (SN ) 1997eg that indicate the presence of a flattened disklike concentration of circumstellar material surrounding aspherical ejecta, with which the disk is misaligned. The polarization across the broad H , H , and He i k5876 lines of SN 1997eg forms closed loops when viewed in the Stokes q-u plane. Such loops occur when the geometrical symmetry of one or both of the Stokes parameters across spectral lines is broken, in this case most likely by occultation of the ejecta by the equatorial circumstellar matter concentration. The polarization of the narrow Balmer lines possesses an intrinsic axis that differs by 12 from that of the elongated ejecta and probably indicates the orientation of the disklike circumstellar material. The existence of two different axes of symmetry in SN 1997eg suggests that neither rotation of the progenitor nor the influence of a companion star can be the sole mechanism creating a preferred axis within the supernova system. Our model supports the emerging hypothesis that the progenitors of some Type IIn supernovae are luminous blue variable stars, whose presupernova mass eruptions form the circumstellar shells that physically characterize the SN IIn subclass. These conclusions, which are independent of interstellar polarization effects, would have been unobservable with only a single epoch of spectropolarimetry.

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The late-time expansion of the ejecta of SN 1987A

Cited by 6 publications

References 14 publications

Spectropolarimetry of the 2012 outburst of SN 2009ip: a bi-polar explosion in a dense, disc-like CSM

Spectropolarimetry of the 2012 outburst of SN 2009ip: a bi-polar explosion in a dense, disc-like CSM

The Axisymmetric Ejecta of Supernova 1987A

The Dual‐Axis Circumstellar Environment of the Type IIn Supernova 1997eg

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