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S.I. Torres, R. Sankrit, W.P. Blair (JHU), J.C. Raymond (CfA)
We present \emph{Hubble Space Telescope} Space Telescope Imaging Spectrograph (STIS) spectra of nonradiative shocks in the northeastern limb of the Cygnus Loop. One observation was obtained through the G140L grating with the STIS longslit perpendicular to the shock. The spectrum covers 1120--1700Å\ and shows the spatial distribution of emissions from N~V \lambda1240, O~V \lambda1371, C~IV \lambda1550, and He~II \lambda1640. The brightest emission in the shocked gas is from a 6\prime\prime section along the slit for O~V, C~IV, and He~II; N~V comes from a 10\prime\prime section, and is slightly ahead of the others. The surface brightnesses of this component are 13.1, 9.0, 6.5, and 0.5 10-16 erg s-1 cm-2 arcsec-2 for C~IV, O~V, He~II, and N~V, respectively. The other observation was obtained through the G140M grating, with the longslit parallel to the shock front and covers 1190--1250Å\@. The two components of N~V doublet are well separated and each component is resolved. We investigate the velocity structure of the filament, and determine the effects of resonance scattering by studying the ratios between the N~V lines.
This work was funded in part by NASA/STScI grant GO-0908001A to Johns Hopkins University.
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.