A ROSAT-detected, New Galactic Supernova Remnant in Sagittarius, G13.3-1.3

Abstract

Faint and diffuse soft X-ray emission, coincident with [S II] strong optical filaments, probably marks a previously unrecognized supernova remnant (SNR) in Sagittarius (1 = 13.3, b = -1.3). ROSAT PSPC data show soft X-rays from an area 40' × 70' with a flux of 1.3 × 10<SUP>-11</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP> between 0.1-2.4 keV. Optical interference-filter images taken of the region reveal a 20' long complex of relatively bright filaments located along the south central boundary of the X-ray region which may be associated with a ridge of faint 11 cm continuum emission. Optical spectra of these filaments show strong [S II] λλ6716, 6731 emission ([S II]/ Hα = 0.85) and [O I] λλ6300, 6364 characteristic of shocked interstellar gas found in SNRs. Both X-rays and optical emissions along the source's NE extent show strong absorption by the dust regions Lynds 332, 336, and 342, indicating a location behind these nebulae. CO emission from this region has been mapped and a kinematic distance derived for absorbing material. The remnant is shown to lie between two absorbing regions located at distances of 2 and 4 kpc.