597 research outputs found
Probing supernovae ejecta by Halpha damping wings
It is predicted that H emission line at the early nebular epoch of
type II-P supernovae may display robust observational effects of damping wings.
This is illustrated by Monte-Carlo simulations. The strength of damping wing
effects may be used to constrain parameters of the line-emitting zone. An
anomalous redshift, width and red wing of H revealed by SN 1997D on day
150 are explained in terms of damping wing effects.Comment: 8 pages, 2 figure
Circumstellar interaction in type Ibn supernovae and SN 2006jc
I analyse peculiar properties of light curve and continua of enigmatic Ibn
supernovae, including SN 2006jc, and argue in favour of the early strong
circumstellar interaction. This interaction explains the high luminosity and
fast flux rise of SN 1999cq, while the cool dense shell formed in shocked
ejecta can explain the smooth early continuum of SN 2000er and unusual blue
continuum of SN 2006jc. The dust is shown to condense in the cool dense shell
at about day 50. Monte Carlo modelling of the He I 7065 \AA line profile
affected by the dust occultation supports a picture, in which the dust resides
in the fragmented cool dense shell, whereas He I lines originate from
circumstellar clouds shocked and fragmented in the forward shock wave.Comment: 10 pages, 6 figures, MNRAS accepte
Moderate Asphericity of the SN 2002ic Circumstellar Envelope
The polarization of SN 2002ic interacting with a dense circumstellar envelope
is calculated in the context of the asymmetric version of a previously proposed
spherical interaction model. The circumstellar envelope is taken to be oblate.
The observed polarization (Wang et al. 2004) can be reproduced for an aspect
ratio of 0.65-0.7 assuming inclination angles >60 degrees. This model predicts
a weak sensitivity of the line profiles to the orientation, in agreement with
the absence of significant variations of the line profiles among SN 2002ic-like
supernovae. We propose a test for distinguishing between the binary and single
star progenitor scenarios based upon the polarization distribution function for
the growing sample of these events.Comment: 13 pages, 4 figs., ApJ, accepte
Macroscopic Parity Violation and Supernova Asymmetries
Core collapse supernovae are dominated by weakly interacting neutrinos. This
provides a unique opportunity for macroscopic parity violation. We speculate
that parity violation in a strong magnetic field can lead to an asymmetry in
the explosion and a recoil of the newly formed neutron star. We estimate the
asymmetry from neutrino-polarized-neutron elastic scattering, polarized
electron capture and neutrino-nucleus elastic scattering in a (partially)
polarized electron gas.Comment: Nine pages Revtex, two postscript figures (included
Type IIP supernova 2008in: the explosion of a normal red supergiant
The explosion energy and the ejecta mass of a type IIP supernova make up the
basis for the theory of explosion mechanism. So far, these parameters have only
been determined for seven events. Type IIP supernova 2008in is another
well-observed event for which a detailed hydrodynamic modeling can be used to
derive the supernova parameters. Hydrodynamic modeling was employed to describe
the bolometric light curve and the expansion velocities at the photosphere
level. A time-dependent model for hydrogen ionization and excitation was
applied to model the Halpha and Hbeta line profiles. We found an ejecta mass of
13.6 Msun, an explosion energy of 5.05x10^50 erg, a presupernova radius of 570
Rsun, and a radioactive Ni-56 mass of 0.015 Msun. The estimated progenitor mass
is 15.5 Msun. We uncovered a problem of the Halpha and Hbeta description at the
early phase, which cannot be resolved within a spherically symmetric model. The
presupernova of SN 2008in was a normal red supergiant with the minimum mass of
the progenitor among eight type IIP supernovae explored by means of the
hydrodynamic modeling. The problem of the absence of type IIP supernovae with
the progenitor masses <15 Msun in this sample remains open.Comment: 6 pages, 8 figures, 1 table, accepted for publication in A&
Luminous type IIP SN 2013ej with high-velocity Ni-56 ejecta
We explore the well-observed type IIP SN 2013ej with peculiar luminosity
evolution. It is found that the hydrodynamic model cannot reproduce in detail
the bolometric luminosity at both the plateau and the radioactive tail. Yet the
ejecta mass of 23-26 Msun and the kinetic energy of (1.2-1.4)x10^51 erg are
determined rather confidently. We suggest that the controversy revealed in
hydrodynamic simulations stems from the strong asphericity of the Ni-56 ejecta.
An analysis of the asymmetric nebular H-alpha line and of the peculiar
radioactive tail made it possible to recover parameters of the asymmetric
bipolar Ni-56 ejecta with the heavier jet residing in the rear hemisphere. The
inferred Ni-56 mass is 0.039 Msun, twice as large compared to a straightforward
estimate from the bolometric luminosity at the early radioactive tail. The bulk
of ejected Ni-56 has velocities in the range of 4000-6500 km/s. The linear
polarization predicted by the model with the asymmetric ionization produced by
bipolar Ni-56 ejecta is consistent with the observational value.Comment: 7 pages, 8 figures, 3 tables. Accepted for publication in MNRA
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