The Axisymmetric Ejecta of Supernova 1987A

By Lifan Wang, J. C. Wheeler, P. Höflich, A. Khokhlov, D. Baade, D. Branch, P. Challis, A. Filippenko, C. Fransson, P. Garnavich and 8 more. 2002

151 citations recorded by the source corpus.

Extensive early observations proved that the ejecta of supernova 1987A (SN 1987A) are aspherical. The most important of these early observations include (1) the "Bochum event" that revealed small-scale spectroscopic structure indicating chemical inhomogeneities of the ejecta, (2) spectropolarimetry that showed deviations from spherical symmetry, and (3) 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 56Ni, and the late-time image, the locus of excitation by 44Ti, are most naturally accounted for by sharing a common position angle of about 14°, 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° 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 Hubble Space Telescope 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] 7300 Å 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 the 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.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

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Citations in the corpus

Simulations of Magnetically Driven Supernova and Hypernova Explosions in the Context of Rapid Rotation (2007, background): “%) of supernovae, and the detection of signatures of asphericity in the generic supernova (Wang et al. 2002, 2003), theMHDmechanism is experiencing a comeback (Ardeljan et al. 2000a, 2000b, 2005; Wheeler et al. 2000, 2002; Akiyama et al. 2003; Yamada & Sawai 2004; Kotake et al. 2004; Mizuno et al.…”
Multidimensional supernova simulations with approximative neutrino transport. I. Neutron star kicks and the anisotropy of neutrino-driven explosions in two spatial dimensions (2006, background): “Recent high-resolution imaging of SN 1987 A with the Hubble Space Telescope (Wang et al. 2002), as well as high values for the measured space velocities of young galactic pulsars, may be interpreted as supporting such a link.”
Non-spherical core collapse supernovae. I. Neutrino-driven convection, Rayleigh-Taylor instabilities, and the formation and propagation of metal clumps (2003, background): “While Nagataki et al. as well as Hungerford et al. do not rule out neutrino emission from the neutron star as an explanation for the assumed asphericity of their shocks, Khokhlov et al. (1999), Wheeler et al. (2002) and Wang et al. (2002) questioned the neutrinodriven mechanism.”
The Type Ic Hypernova SN 2002ap (2002, unknown): “The present data show no clear signature of asymmetry, except perhaps for some polarization (Wang et al. 2002; Kawabata et al. 2002), which is smaller than that of SN 1998bw.”
The Magnetorotational Instability in Core-Collapse Supernova Explosions (2002, background): “Iron, 954 silicon, and other heavy elements in Cas A are distributed in this way (Hwang et al. 2000), and there is some evidence for this distribution in SN 1987A (Wang et al. 2002).”
Nucleosynthesis in Stars and the Chemical Enrichment of Galaxies (2013, background): “Hypernovae are also characterized by asphericity according to observations of polarization and emission-line features (e.g., Maeda et al. 2002, Wang et al. 2002).”
General relativistic magnetohydrodynamic simulations of the jet formation and large-scale propagation from black hole accretion systems (2006, background): “…polarised, asymmetric, and often bi-polar indicating a strong role of rotation and a magnetic field (see, e.g., Wang & Wheeler 1996; Wheeler, Yi, Höflich, & Wang 2000; Wang, Howell, Höflich, & Wheeler 2001; Wang et al. 2002; Wang, Baade, Höflich, & Wheeler 2003, and references therein).”
Non-spherical core collapse supernovae - II. The late-time evolution of globally anisotropic neutrino-driven explosions and their implications for SN 1987 A (2005, methodology): “It is particularly noteworthy that the degree of polarization was only 0.1% two days after the explosion and increased to 1.1% at about day 200, indicating that the scattering surface became increasingly asymmetric as the observations probed the deeper layers of the ejecta (Wang et al. 2002).”
Multidimensional supernova simulations with approximative neutrino transport. II. Convection and the (2007, background): “In the case of Supernova 1987A this non-spherical distribution of the ejecta can even be directly imaged with the Hubble Space Telescope (Wang et al. 2002).”
Supernova Nucleosynthesis in Population III 13-50 M☉ Stars and Abundance Patterns of Extremely Metal-poor Stars (2007, background): “However, such one-dimensional hydrodynamic determinations may not be relevant, because SN explosions are found to be aspherical (e.g., Kawabata et al. 2002; Leonard et al. 2002; Wang et al. 2002, 2003;Maeda et al. 2002, 2006a, 2006b;Mazzali et al. 2005;Chugai et al. 2005).”
Experimental astrophysics with high power lasers and Z pinches (2004, background): “These have shown that between two weeks and two months after the explosion most SNe manifest gross deviations from spherical symmetry Jeffery 1991; Trammell et al., 1993; Tran et al., 1997; Leonard et al., 2000; Wang et al., 2002 .”
Numerical Analysis of Standing Accretion Shock Instability with Neutrino Heating in Supernova Cores (2005, background): “Over the last decades, it has been observationally suggested that the core-collapse su- pernovae are generally aspherical (Wang et al. 1996, 2001, 2002).”
Spectropolarimetry of Supernovae (2008, background): “…L., & Wheeler, J. C. 1998, ApJl, 504, L87 Wang et al. (2001)Wang, L., Howell, D. A., Höflich, P., & Wheeler, J. C. 2001, ApJ, 550, 1030 Wang et al.(2002)Wang, L., Wheeler, J. C., Höflich, P., Khokhlov, A., Baade, D., Branch, D., Challis, P., Filippenko, A. V., Fransson, C.,…”
The Rates of Hypernovae and Gamma-Ray Bursts: Implications for Their Progenitors (2004, background): “SN 1987A was not a hypernova, but there is some evidence that the explosion was jet-like (e.g., Wang et al. 2002; also see Joss & Becker 2003).”