Far Ultraviolet Spectroscopic Explorer Observations of a Supernova Remnant in the Line of Sight to HD 5980 in the Small Magellanic Cloud

摘要

We report a detection of far ultraviolet absorption from the supernovaremnant SNR 0057 - 7226 in the Small Magellanic Cloud (SMC). The absorption isseen in the Far Ultraviolet Spectroscopic Explorer (FUSE) spectrum of theLBV/WR star HD 5980. Absorption from O VI 1032 and C III 977 is seen at avelocity of +300 km/s with respect to the Galactic absorption lines, +170 km/swith respect to the SMC absorption. The O VI 1038 line is contaminated by H_2absorption, but is present. These lines are not seen in the FUSE spectrum ofSk80, only ~1' (~17 pc) away from HD 5980. No blue-shifted O VI 1032 absorptionfrom the SNR is seen in the FUSE spectrum. The O VI 1032 line in the SNR iswell described by a Gaussian with FWHM=75 km/s. We find log N(OVI)=14.33-14.43, which is roughly 50% of the rest of the O VI column in the SMC(excluding the SNR) and greater than the O VI column in the Milky Way haloalong this sight line. The N(C IV)/N(O VI) ratio for the SNR absorption is inthe range of 0.12-0.17, similar to the value seen in the Milky Way disk, andlower than the halo value, supporting models in which SNRs produce the highlyionized gas close to the plane of the Galaxy, while other mechanisms occur inthe halo. The N(C IV)/N(O VI) ratio is also lower than the SMC ratio along thissight line, suggesting that other mechanisms contribute to the creation of theglobal hot ionized medium in the SMC. The O VI, C IV, and Si IV apparent columndensity profiles suggest the presence of a multi-phase shell followed by aregion of higher temperature gas.