We study the effects of jetlike explosion in SN 1987A. Calculations of the explosive nucleosynthesis and the matter mixing in a jetlike explosion are performed, and their results are compared with the observations of SN 1987A. It is shown that the jetlike explosion model is favored because the radioactive nuclei 44Ti is produced in a sufficient amount to explain the observed luminosity at 3600 days after the explosion. This is because the active alpha-rich freeze-out takes place behind the strong shock wave in the polar region. It is also shown that the observed line profiles of Fe [II] are well reproduced by the jetlike explosion model. In particular, the fast-moving component traveling at 3000-4000 km s-1 is well reproduced; it has not been reproduced by the spherical explosion models. Moreover, we conclude that the favored degree of a jetlike explosion to explain the tail of the light curve is consistent with the one favored in the calculation of the matter mixing. The concluded ratio of the velocity along to the polar axis relative to that in the equatorial plane at the Si/Fe interface is ~ 2 : 1. This conclusion will give good constraints on the calculations of the dynamics of the collapse-driven supernova. We also found that the required amplitude for the initial velocity fluctuations as a seed of the matter mixing is ~30%. This result supports the idea that the origin of the fluctuations is the dynamics of the core collapse rather than the convection in the progenitor. The asymmetry of the observed line profiles of Fe [II] can be explained when the assumption of the equatorial symmetry of the system is removed, which can be caused by the asymmetry of the jetlike explosion with respect to the equatorial plane. In the case of SN 1987A, the jet on the north pole has to be stronger than that on the south pole in order to reproduce the observed asymmetric line profiles. Such an asymmetry may also be the origin of the pulsar kick. When we believe some theories that cause such an asymmetric explosion, the proto-neutron star born in SN 1987A will be moving in the southern part of the remnant.

Effects of Jetlike Explosion in SN 1987A

We present the discovery of several new regions of interaction between the ejecta and equatorial circumstellar ring of SN 1987A, an interaction leading to a much-expanded development of the supernova remnant. We also trace the development of the first such "hot spot," discovered in 1997, back to 1995. Later hot spots seem to have emerged by early 1999. We discuss mechanisms for the long delay between the first and later spots.

On the Emergence and Discovery of Hot Spots in SNR 1987A

We present a new formalism to describe the ratios and profiles of emission lines from hydrogen in Balmer-dominated shocks. We use this model to interpret the measured widths and ratios of broad and narrow H-alpha, H-beta and Ly-alpha emission lines in supernova remnants (SNRs). Our model results agree fairly well with those obtained previously by Chevalier, Kirshner & Raymond (1980) and are consistent with observations of several SNRs. The same model fails to account for the ratio of broad to narrow line emission from the reverse shock in SNR 1987A as observed by Heng et al. (2006). We suggest that this discrepancy between theory and observation results from a faulty assumption that Balmer-dominated shocks can be treated as sharp discontinuities. If the spatial structure of the shock transition zone is taken into account, the predicted ratios of broad to narrow line emission in most SNRs will change by modest factors, but the ratio in SNR 1987A will increase substantially. Significantly greater shock velocities will be required to account for the observed full widths at half-maximum of the broad emission lines in most SNRs.

Balmer-Dominated Shocks Revisited

We present a new formalism to describe the ratios and profiles of emission lines from hydrogen in Balmer- dominated shocks. We use this model to interpret the measured widths and ratios of broad and narrow H� ,H � , and Lyemissionlinesinsupernovaremnants(SNRs).Ourmodelresultsagreefairlywellwiththoseobtainedpreviously by Chevalier, Kirshner, & Raymond and are consistent with observations of several SNRs. The same model fails to accountfortheratioof broadtonarrowlineemission fromthereverseshockinSNR1987Aasobserved byHengand coworkers. We suggest that this discrepancy between theory and observation results from a faulty assumption that Balmer-dominatedshockscanbetreatedassharpdiscontinuities.Ifthespatialstructureoftheshocktransitionzoneis taken into account, the predicted ratios of broad to narrow line emission in most SNRs will change by modest fac- tors, but the ratio in SNR 1987Awill increase substantially. Significantly greater shock velocities will be required to account for the observed full widths at half-maximum of the broad emission lines in most SNRs. Subject headingg shock waves — supernova remnants

http://jilawww.colorado.edu/~dick//Balmer.pdf

Balmer‐dominated Shocks Revisited

We discuss the X-ray emission observed from supernova remnant 1987A with the Chandra X-Ray Observatory. We analyze a high-resolution spectrum obtained in 1999 October with the high-energy transmission grating (HETG). From this spectrum we measure the strengths and an average profile of the observed X-ray lines. We also analyze a high signal-to-noise ratio CCD spectrum obtained in 2000 December. The good statistics (?9250 counts) of this spectrum and the high spatial resolution provided by the telescope allow us to perform spectroscopic analyses of different regions of the remnant. We discuss the relevant shock physics that can explain the observed X-ray emission. The X-ray spectra are well fitted by plane-parallel shock models with postshock electron temperatures of ?2.6 keV and ionization ages of ?6 ? 1010 cm-3 s. The combined X-ray line profile has a FWHM of ?5000 km s-1, indicating a blast-wave speed of ?3500 km s-1. At this speed, plasma with a mean postshock temperature of ?17 keV is produced. This is direct evidence for incomplete electron-ion temperature equilibration behind the shock. Assuming this shock temperature, we constrain the amount of collisionless electron heating at the shock front at Te0/Ts = 0.11. We find that the plasma has low metallicity (abundances are ?0.1-0.4 solar) and is nitrogen enriched (N/O ? 0.8 by number), similar to abundances found for the equatorial ring. Analysis of the spectra from different regions of the remnant reveals slight differences in the parameters of the emitting plasma. The plasma is cooler near the optical spot 1 (at position angle ?30?) and in the eastern half of the remnant, where the bright optical spots are found, than in the western half, consistent with the presence of slower (?500 km s-1) shocks entering denser ring material. There is an overall flux asymmetry between the two halves, with the eastern half being 15%-50% brighter (depending on how the center of the remnant is defined). However, our spectroscopic analysis shows that less than 5% of the overall X-ray emission could come from a slow shock component. Therefore the flux asymmetry cannot fully be due to X-rays produced by the blast wave entering the ring, but rather indicates an asymmetry in the global interaction with the circumstellar material interior to the ring.

The X-Ray Spectrum of Supernova Remnant 1987A

We describe and model high velocity (~15,000 km/s) Lyman alpha and Balmer alpha emission from supernova remnant 1987A seen in September and October 1997 with the Space Telescope Imaging Spectrograph. Part of this emission comes from a reverse shock located at ~75% of the radius of the inner boundary of the inner circumstellar ring and confined within 30 degrees of the equatorial plane. Departure from axisymmetry in the Lyman alpha and Balmer alpha emission correlates with that seen in nonthermal radio emission and reveals an asymmetry in the circumstellar gas distribution. We also see diffuse high velocity Lyman alpha emission from supernova debris inside the reverse shock that may be due to excitation by nonthermal particles accelerated by the shock.

New HST Observations of High Velocity Lyman Alpha and Balmer Alpha in SNR 1987A

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New HST Observations of High Velocity Lyman Alpha and Balmer Alpha in SNR 1987A