Astro-2/UIT Observations of Supernova Remnants

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Session 20 -- Astro 2
Display presentation, Tuesday, June 13, 1995, 9:20am - 6:30pm

[20.13] Astro-2/UIT Observations of Supernova Remnants

R.H.Cornett (Hughes STX,GSFC/LASP), T.P.Stecher (GSFC/LASP), and the UIT Team

During the recent Astro-2 mission the Ultraviolet Imaging Telescope (UIT) obtained far-UV (FUV: 1200-1800\AA) images of 14 positions on supernova remnants (SNRs). UIT has produced the only images of SNRs in this bandpass; the images have wide fields (40 arcmin diameter), high spatial resolution ($\sim$3~arcsec) and high sensitivity (typically 1\dexp{-18} \flx, averaged over the 225-400\AA~bandpasses). The fields are centered on positions of particular interest on Galactic SNRs, having extensive X-ray, IUE and groundbased observations and theoretical work. Field centers include several Cygnus Loop positions: nearly complete coverage of the eastern edge; a non-radiative shock on the northeast shell; Miller's Position 1; and Miller's Position 3 on the western edge. In addition, two Vela SNR positions, a Puppis A position, and the SN1006 remnant were imaged.

Most images were made in the UIT ``B5'' bandpass, which is sensitive from about 1450\AA~ to 1800\AA; some positions were also imaged in the ``B1'' filter which extends shortward to 1300\AA. The UIT bandpasses encompass several potentially strong emission features, depending on conditions: the hydrogen two-photon continuum, and CII 1335\AA, OV 1371\AA, (OIV],SIV], SiIV)1409\AA, NIV 1485\AA, CIV 1549\AA, HeII 1640\AA, OIII] 1666\AA, NIII] 1745\AA, SiIII] 1892\AA~and CIII] 1909\AA~emission lines may all contribute. However, because of high shock velocities, the UIT Astro-1 B5 image of an eastern Cygnus Loop field was dominated by the CIV 1549\AA~resonance line, and offered a clear contrast with [OIII] 5007\AA, which has similar excitation characteristics but is seen only in small optical depths.

UIT images of observed SNR fields will be presented and discussed. Shock models, images made in other bandpasses, and ultraviolet spectra for positions within the UIT fields will be used to interpret emission seen in the images.

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