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71.
72.
M.F. Graham R.J. Smith J. Meaburn M. Bryce 《Monthly notices of the Royal Astronomical Society》2001,326(2):539-542
The giant filamentary shell, DEM 171, is found to be expanding at approximately 37 km s−1 . A supernova and stellar wind origin are both explored as possible causes for the expanding shell. A stellar wind origin would imply a mass-loss rate of the order of 10−5 M⊙ yr−1 , indicating that it could be caused by a Wolf–Rayet star. A number of blue stars are found to lie within the shell and one is identified as a Wolf–Rayet candidate. 相似文献
73.
T. Morel R. Doyon N. St-Louis 《Monthly notices of the Royal Astronomical Society》2002,329(2):398-410
In an effort better to calibrate the supernova rate of starburst galaxies as determined from near-infrared [Fe ii ] features, we report on a [Fe ii ] λ 1.644 μm line-imaging survey of a sample of 42 optically selected supernova remnants (SNRs) in M33. A wide range of [Fe ii ] luminosities are observed within our sample (from less than 6 to 695 L⊙ ). Our data suggest that the bright [Fe ii ] SNRs are entering the radiative phase and that the density of the local interstellar medium (ISM) largely controls the amount of [Fe ii ] emission. We derive the following relation between the [Fe ii ] λ 1.644 μm line luminosity of radiative SNRs and the electronic density of the post-shock gas, n e : L [Fe ii ] (cm−3 ). We also find a correlation in our data between L [Fe ii ] and the metallicity of the shock-heated gas, but the physical interpretation of this result remains inconclusive, as our data also show a correlation between the metallicity and n e . The dramatically higher level of [Fe ii ] emission from SNRs in the central regions of starburst galaxies is most likely due to their dense environments, although metallicity effects might also be important. The typical [Fe ii ]-emitting lifetime of a SNR in the central regions of starburst galaxies is found to be of the order of 104 yr. On the basis of these results, we provide a new empirical relation allowing the determination of the current supernova rate of starburst galaxies from their integrated near-infrared [Fe ii ] luminosity. 相似文献
74.
S. O. Tagieva 《Astronomy Letters》2002,28(5):310-315
The dependences of various parameters for S-and C-type supernova remnants (SNRs) on their diameters are investigated. Only SNRs with D≤40 pc that expand initially within H II regions and, subsequently, in dense media are considered. The expansion velocities and thermal electron densities of these SNRs were found to decrease with increasing diameter, on average, as D ?1 and D ?0.5, respectively. H II regions hamper the detection of SNRs; this effect is particularly pronounced in regions with 270°≤1≤300° and 330°≤1≤360°. The X-ray luminosities of SNRs born in dense media increase by an order of magnitude when their diameters reach ~30 pc. After the SNR diameters reach ~40 pc, their radio and X-ray luminosities decrease sharply. 相似文献
75.
Sidney Van den Bergh 《Journal of Astrophysics and Astronomy》1980,1(1):67-70
A massive binary, in which the primary becomes a supernova, should leave a luminous secondary near the centre of its remnant.
Contrary to expectation no statistically significant excess of OB stars is, however, found near the centres of optically visible
galactic supernova remnants. 相似文献
76.
We use the recently introduced concept of a ‘window’ of magnetic field strengths in which pulsars can be active to explain
the variation in morphology of supernova remnants. The striking difference between shell-type and filled-type remnants is
attributed to differences in he magnetic field strengths of the neutron stars left by the respective Supernovae. Field strengths
of a value permitting pulsar activity result in particle production and Crab-like centrally concentrated remnants. Other field
values lead to strong magnetic dipole radiation and consequent shell formation (e.g. Cas A). Several apparent inconsistencies concerning pulsar-supernova associations appear to find a logical explanation on
the basis of this hypothesis. 相似文献
77.
Based on observations of SN 1999em, we determined the physical parameters of this supernova using hydrodynamic calculations including nonequilibrium radiative transfer. Taking the distance to SN 1999em estimated by the expanding photosphere method (EPM) to be D = 7.5 Mpc, we found the parameters of the presupernova: radius R = 450R⊙, mass M = 15M⊙, and explosion energy E = 7 × 1050 erg. For the distance D = 12 Mpc determined from Cepheids, R, M, and E must be increased to the following values: R = 1000R⊙, M = 18M⊙, and E = 1051 erg. We show that one cannot restrict oneself to using the simple analytical formulas relating the supernova and presupernova parameters to obtain reliable parameters for type-IIP presupernovae. 相似文献
78.
The commonly used classical equipartition or minimum‐energy estimate of total magnetic fields strengths from radio synchrotron intensities is of limited practical use because it is based on the hardly known ratio K of the total energies of cosmic ray protons and electrons and also has inherent problems. We present a revised formula, using the number density ratio K for which we give estimates. For particle acceleration in strong shocks K is about 40 and increases with decreasing shock strength. Our revised estimate for the field strength gives larger values than the classical estimate for flat radio spectra with spectral indices of about 0.5–0.6, but smaller values for steep spectra and total fields stronger than about 10 µG. In very young supernova remnants, for example, the classical estimate may be too large by up to 10×. On the other hand, if energy losses of cosmic ray electrons are important, K increases with particle energy and the equipartition field may be underestimated significantly. Our revised larger equipartition estimates in galaxy clusters and radio lobes are consistent with independent estimates from Faraday rotation measures, while estimates from the ratio between radio synchrotron and X‐ray inverse Compton intensities generally give much weaker fields. This may be explained e.g. by a concentration of the field in filaments. Our revised field strengths may also lead to major revisions of electron lifetimes in jets and radio lobes estimated from the synchrotron break frequency in the radio spectrum. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
79.
D. W. E. Green 《Astronomische Nachrichten》2005,326(2):101-111
The position of the supernova of 1604 (V843 Oph) is re‐assessed, with relevant discussion pertaining to the present‐day remnant, 3C 358. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
80.
We present high spatial resolution X-ray spectroscopy of supernova remnant G292.0+1.8 made with Chandra observations.The X-ray emitting region of this remnant was divided into 25×25 pixels with a scale of 20 " ×20" each.Spectra of328 pixels were created and fitted with an absorbed one component non-equilibrium ionization model.With the spectral analysis results,we obtained maps of absorbing column density,temperature,ionization age and abundances for O,Ne,Mg,Si,S and Fe.The abundances of O,Ne and Mg show tight correlations between each other in the range of about two orders of magnitude,suggesting that they are all from explosive C/Ne burning.Meanwhile,the abundances of Si and S are also well correlated,indicating that they are the ashes of explosive O-burning or incomplete Si-burning.The Fe emission lines are not prominent in the whole remnant,and their abundance is significantly reduced,indicating that the reverse shock may not have propagated to the Fe-rich ejecta.Based on relative abundances of O,Ne,Mg,Si and Fe to Si,we suggest a progenitor mass of 25- 30 M_⊙ for this remnant. 相似文献