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Intermediate-velocity gas observed towards the Shajn 147 SNR

S. Sallmen·B. Y. Welsh
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Abstract

(Abridged) We present high-resolution spectra of the interstellar NaI and CaII absorption lines for 3 early-type stars along the line-of-sight towards the Shajn 147 SNR. These are supplemented with far-UV aborption spectra of HD 36665 and HD 37318 recorded with the NASA FUSE satellite. The observations reveal intermediate-velocity (IV) absorption features at V_helio = +92 km/s towards HD 37318 and -65 & -52 km/s towards HD 36665. These IV components can be associated with the expansion of the SNR. The observations suggest that the IV component at +92 km/s towards HD 37318 is composed mainly of warm and ionized gas. The two IV components observed towards HD 36665 are likely composed of both neutral and ionized gas shells. Highly ionized gas was detected in the OVI (1032Å) absorption line at +40 km/s towards both stars. This hot gas component is characterized by a columnn density ratio (N(CIV)/N(OVI) < 0.27) consistent with that predicted by current models of evolved SNRs, but we cannot preclude its origin in the ISM. Column-density ratios have been derived for the IV gas components detected towards S147, as well as for fast-moving gas observed towards two other SNRs in order to gain some insight into the behavior of element abundances in the disturbed interstellar gas associated with these regions. In all cases except for Na and Ca, these elements appear to be present with near-solar abundance ratios. (Abridged)

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S. Sallmen, B. Y. Welsh. 2004-09-07. Intermediate-velocity gas observed towards the Shajn 147 SNR. https://doi.org/10.1051/0004-6361%3A20040093

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