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Supernova Explosions (supernova + explosion)

Distribution by Scientific Domains
Physics and Astronomy100%

Selected Abstracts

PSR J0609+2130: a disrupted binary pulsar?

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2004
D. R. Lorimer
ABSTRACT We report the discovery and initial timing observations of a 55.7-ms pulsar, J0609+2130, found during a 430-MHz drift-scan survey with the Arecibo radio telescope. With a spin-down rate of 3.1 × 10,19 s s,1 and an inferred surface dipole magnetic field of only 4.2 × 109 G, J0609+2130 has very similar spin parameters to the isolated pulsar J2235+1506 found by Camilo, Nice & Taylor. While the origin of these weakly magnetized isolated neutron stars is not fully understood, one intriguing possibility is that they are the remains of high-mass X-ray binary systems which were disrupted by the supernova explosion of the secondary star. [source]

Isotopic compositions of different presolar silicon carbide size fractions from the Murchison meteorite

METEORITICS & PLANETARY SCIENCE, Issue 5 2000
Sachiko AMARI
Ratios of 12C/13C range from 37 to 42 and 14N/15N ratios from 370 to 520, within the range of single-grain measurements on coarser samples and in agreement with an asymptotic giant branch (AGB) star origin of most of the grains. Variations among size fractions do not show any simple trend and can be explained by varying contamination with isotopically normal material. Silicon isotopic ratios vary only little and, with one exception, lie to the right of the singlegrain mainstream correlation line. This might indicate a higher percentage of the minor populations Y and Z among finer grain-size fractions. All bulk samples have large 26Mg excesses attributed to the presence of short-lived 26Al at the time of grain formation. Inferred 26Al/27Al ratios are much larger than those measured in single larger mainstream grains. This is probably because of the presence of SiC grains of type X; we obtain an estimate of 0.4 for their 26Al/27Al ratio. Our Ca-isotopic measurements, the first made on presolar SiC grains, show excesses in 42Ca and 43Ca, which is in general agreement with theoretical expectations for AGB stars. Calcium-44 excesses are much larger than expected and are probably because of X grains, which have high44Ca excesses because of the decay of short-lived 44Ti produced in supernova explosions. We arrive at an estimate of 0.014 for the initial 44Ti/48Ti ratio of the X grains, within the range obtained from previous single X grain measurements. The Ti-isotopic ratios of the bulk samples show a V-shaped pattern with excesses of all isotopes relative to 48Ti. Isotopes 46Ti, 47Ti, and 50Ti show excesses relative to the correlation between Ti and Si ratios for single grains and are in general agreement with theoretical models of s-process nucleosynthesis in AGB stars. In contrast, 49Ti does not show any excess relative to the singlegrain data; it also fails to agree with theory, which predicts much larger excesses than observed. Measured 53Cr/52Cr and 57Fe/56Fe ratios are normal within errors. The first result is expected even for Cr in AGB star envelopes, but the second result suggests that most of the Fe analyzed originates from contamination. We have found no simple trends in isotopic composition with respect to grain size that can be interpreted in terms of nucleosynthetic origin, unlike the results for Kr, Xe, Ba, and Sr. [source]

Massive stars exploding in a He-rich circumstellar medium , I. Type Ibn (SN 2006jc-like) events

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2008
A. Pastorello
ABSTRACT We present new spectroscopic and photometric data of the Type Ibn supernovae 2006jc, 2000er and 2002ao. We discuss the general properties of this recently proposed supernova family, which also includes SN 1999cq. The early-time monitoring of SN 2000er traces the evolution of this class of objects during the first few days after the shock breakout. An overall similarity in the photometric and spectroscopic evolution is found among the members of this group, which would be unexpected if the energy in these core-collapse events was dominated by the interaction between supernova ejecta and circumstellar medium. Type Ibn supernovae appear to be rather normal Type Ib/c supernova explosions which occur within a He-rich circumstellar environment. SNe Ibn are therefore likely produced by the explosion of Wolf,Rayet progenitors still embedded in the He-rich material lost by the star in recent mass-loss episodes, which resemble known luminous blue variable eruptions. The evolved Wolf,Rayet star could either result from the evolution of a very massive star or be the more evolved member of a massive binary system. We also suggest that there are a number of arguments in favour of a Type Ibn classification for the historical SN 1885A (S-Andromedae), previously considered as an anomalous Type Ia event with some resemblance to SN 1991bg. [source]

Light curves for off-centre ignition models of Type Ia supernovae

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2007
S. A. Sim
ABSTRACT Motivated by recent models involving off-centre ignition of Type Ia supernova explosions, we undertake three-dimensional time-dependent radiation transport simulations to investigate the range of bolometric light-curve properties that could be observed from supernovae in which there is a lop-sided distribution of the products from nuclear burning. We consider both a grid of artificial toy models which illustrate the conceivable range of effects and a recent three-dimensional hydrodynamical explosion model. We find that observationally significant viewing angle effects are likely to arise in such supernovae and that these may have important ramifications for the interpretation of the observed diversity of Type Ia supernova and the systematic uncertainties which relate to their use as standard candles in contemporary cosmology. [source]

Deep H, imagery of the Eridanus shells

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 1 2001
P. Boumis
A deep H, image of interlocking filamentary arcs of nebulosity has been obtained with a wide-field (,30° diameter) narrow-band filter camera combined with a charge-coupled device as a detector. The resultant mosaic of images, extending to a galactic latitude of ,65°, has been corrected for field distortions and had galactic coordinates superimposed on it to permit accurate correlations with the most recent H i (21 cm), X-ray (0.75 keV) and FIR (IRAS 100 ,m) maps. Furthermore, an upper limit of 0.13 arcsec yr,1 to the expansion proper motion of the primary 25° long nebulous arc has been obtained by comparing a recent H, image obtained with the San Pedro Martir telescope of its filamentary edge with that on a Palomar Observatory Sky Survey E plate obtained in 1951. It is concluded that these filamentary arcs are the superimposed images of separate shells (driven by supernova explosions and/or stellar winds) rather than the edges of a single ,superbubble' stretching from Barnard's Arc (and the Orion Nebula) to these high galactic latitudes. The proper motion measurement argues against the primary H,-emitting arc being associated with the giant radio loop (Loop 2) except in extraordinary circumstances. [source]

Influence of Ohmic diffusion on the excitation and dynamics of MRI

ASTRONOMISCHE NACHRICHTEN, Issue 1 2010
M.J. Korpi
Abstract In this paper we make an effort to understand the interaction of turbulence generated by the magnetorotational instability (MRI) with turbulence from other sources, such as supernova explosions (SNe) in galactic disks. First we perform a linear stability analysis (LSA) of non-ideal MRI to derive the limiting value of Ohmic diffusion that is needed to inhibit the growth of the instability for different types of rotation laws. With the help of a simple analytical expression derived under first-order smoothing approximation (FOSA), an estimate of the limiting turbulence level and hence the turbulent diffusion needed to damp the MRI is derived. Secondly, we perform numerical simulations in local cubes of isothermal nonstratified gas with external forcing of varying strength to see whether the linear result holds for more complex systems. Purely hydrodynamic calculations with forcing, rotation and shear are made for reference purposes, and as expected, non-zero Reynolds stresses are found. In the magnetohydrodynamic calculations, therefore, the total stresses generated are a sum of the forcing and MRI contributions. To separate these contributions, we perform reference runs with MRI-stable shear profiles (angular velocity increasing outwards), which suggest that the MRI-generated stresses indeed become strongly suppressed as function of the forcing. The Maxwell to Reynolds stress ratio is observed to decrease by an order of magnitude as the turbulence level due to external forcing exceeds the predicted limiting value, which we interpret as a sign of MRI suppression. Finally, we apply these results to estimate the limiting radius inside of which the SN activity can suppress the MRI, arriving at a value of 14 kpc (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]