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

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