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Title: Physical nature of the [S II]-bright shell nebulae N70 and N185

Abstract

N70 and N185 are two large (≥100 pc in diameter) shell nebulae in the Large Magellanic Cloud (LMC). Their high [S II]/Hα ratios rival those of supernova remnants (SNRs), but they are not confirmed as SNRs. To study their physical nature, we have obtained XMM-Newton X-ray observations and high-dispersion long-slit echelle spectroscopic observations of these two nebulae. The X-ray spectra of both nebulae can be well interpreted with an optically thin thermal (∼0.2 keV) plasma with the average LMC abundance in a collisional ionization equilibrium. N70 encompasses the OB association LH114. Although N70 has a modest expansion velocity and essentially thermal radio emission, its diffuse X-ray luminosity (∼6.1 × 10{sup 35} erg s{sup –1}) is higher than that from a quiescent superbubble with N70's density, size, and expansion velocity; thus, N70 is most likely a superbubble that is recently energized by an interior SNR. N185 does not contain any known OB association, and its X-ray luminosity is an order of magnitude lower than expected if it is a quiescent superbubble. N185 has nonthermal radio emission and has high-velocity material expanding at nearly 200 km s{sup –1}, similar to many known SNRs in the LMC. Its X-ray luminosity (∼1.9 × 10{supmore » 35} erg s{sup –1}) is also consistent with that of an evolved SNR. We therefore suggest that N185 is energized by a recent supernova.« less

Authors:
; ;  [1]; ;  [2];  [3]
  1. School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China)
  2. University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States)
  3. Columbus State University, 4225 University Avenue, Columbus, GA 31907 (United States)
Publication Date:
OSTI Identifier:
22365192
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 792; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ABUNDANCE; DENSITY; DISPERSIONS; EMISSION; EQUILIBRIUM; EXPANSION; KEV RANGE; LUMINOSITY; MAGELLANIC CLOUDS; NEBULAE; PLASMA; SUPERNOVA REMNANTS; TYPE II SUPERNOVAE; VELOCITY; X RADIATION; X-RAY SPECTRA

Citation Formats

Zhang, Ning-Xiao, Jiang, Bing, Chen, Yang, Chu, You-Hua, Gruendl, R. A., and Williams, R. M. Physical nature of the [S II]-bright shell nebulae N70 and N185. United States: N. p., 2014. Web. doi:10.1088/0004-637X/792/1/58.
Zhang, Ning-Xiao, Jiang, Bing, Chen, Yang, Chu, You-Hua, Gruendl, R. A., & Williams, R. M. Physical nature of the [S II]-bright shell nebulae N70 and N185. United States. doi:10.1088/0004-637X/792/1/58.
Zhang, Ning-Xiao, Jiang, Bing, Chen, Yang, Chu, You-Hua, Gruendl, R. A., and Williams, R. M. Mon . "Physical nature of the [S II]-bright shell nebulae N70 and N185". United States. doi:10.1088/0004-637X/792/1/58.
@article{osti_22365192,
title = {Physical nature of the [S II]-bright shell nebulae N70 and N185},
author = {Zhang, Ning-Xiao and Jiang, Bing and Chen, Yang and Chu, You-Hua and Gruendl, R. A. and Williams, R. M.},
abstractNote = {N70 and N185 are two large (≥100 pc in diameter) shell nebulae in the Large Magellanic Cloud (LMC). Their high [S II]/Hα ratios rival those of supernova remnants (SNRs), but they are not confirmed as SNRs. To study their physical nature, we have obtained XMM-Newton X-ray observations and high-dispersion long-slit echelle spectroscopic observations of these two nebulae. The X-ray spectra of both nebulae can be well interpreted with an optically thin thermal (∼0.2 keV) plasma with the average LMC abundance in a collisional ionization equilibrium. N70 encompasses the OB association LH114. Although N70 has a modest expansion velocity and essentially thermal radio emission, its diffuse X-ray luminosity (∼6.1 × 10{sup 35} erg s{sup –1}) is higher than that from a quiescent superbubble with N70's density, size, and expansion velocity; thus, N70 is most likely a superbubble that is recently energized by an interior SNR. N185 does not contain any known OB association, and its X-ray luminosity is an order of magnitude lower than expected if it is a quiescent superbubble. N185 has nonthermal radio emission and has high-velocity material expanding at nearly 200 km s{sup –1}, similar to many known SNRs in the LMC. Its X-ray luminosity (∼1.9 × 10{sup 35} erg s{sup –1}) is also consistent with that of an evolved SNR. We therefore suggest that N185 is energized by a recent supernova.},
doi = {10.1088/0004-637X/792/1/58},
journal = {Astrophysical Journal},
number = 1,
volume = 792,
place = {United States},
year = {Mon Sep 01 00:00:00 EDT 2014},
month = {Mon Sep 01 00:00:00 EDT 2014}
}
  • We present the results of wide integral-field near-infrared (1.0-1.8 {mu}m) spectroscopic observations of the southeastern shell of the young core-collapse supernova remnant (SNR) G11.2-0.3. We first construct [Fe II] 1.644 {mu}m line images of three bright clumps from the obtained spectral image cubes and compare them with those of other transitions such as [Fe II] 1.257, [Fe II] 1.534, and He I 1.083 {mu}m line images. This allows us to estimate the electron density ({approx}4700-9400 cm{sup -3}) and extinction (A{sub V} {approx} 16-20 mag) of the shell, including a detailed two-dimensional distribution of the properties in the brightest clump, asmore » well as the discovery of a faint high-velocity ({approx} - 440 km s{sup -1}) component in the clump. Our SNR shock model calculations estimate the pre-shock number density of {approx}250-500 cm{sup -3} and shock speed of {approx}80-250 km s{sup -1} in the [Fe II]-emitting region of the SNR. The comparison between the observed and modeled radial profiles of the line intensities and their ratios reveals that the shell is composed of multiple thin filaments which have been likely formed in episodic mass-loss processes of a progenitor star. The discovery of the faint high-velocity component supports the interpretation that the southeastern shell of G11.2-0.3 is mainly composed of circumstellar material with contamination by supernova ejecta and also that its ejected material was expelled primarily in the southeast-northwest direction.« less
  • Vapour pressure geometry (VPO) and viscometric technique were used to reveal the true molecular weight of asphaltenes and the degree of association in solvent of different polarities at different temperatures. The number average molecular weight of unassociated asphaltenes was found to be 935 g/mol, in nitrobenzene at 120 C. The degrees of association were determined from VPO in benzene at 37,45, 60 C, in chlorobenzene at 37, 45, 60 and 90 C, in THF at 37, 45, 60 C and in nitrobnenzene at 90 C. The degree of association determined by viscometric method at 37, 45 and 60 C, inmore » these solvents were found to be in approximate agreement with that found by VPO. Data derived by means of viscometric and osmometric methods consolidated the recognition that asphaltenes could be similar to macromolecules structurally.« less