Intermediate-velocity gas observed towards the Shajn 147 SNR

Abstract

Abstract. We present high-resolution spectra (R ∼ 3 km s −1 ) of the interstellar Na  and Ca  interstellar absorption lines observed towards 3 early-type stars with distances of 360 to 1380 pc along the line-of-sight towards the 800 pc distant Shajn 147 (S147) Supernova Remnant (SNR). These data are supplemented with far-UV (912-1180 Å) aborption spectra of HD 36665 and HD 37318 recorded with the NASA Far Ultraviolet Spectroscopic Explorer (FUSE) satellite. The observations reveal intermediate-velocity (IV) absorption features at V helio = +92 km s −1 towards HD 37318 and at V helio = −65 and −52 km stowards HD 36665, in addition to several other gas cloud components with lower velocity. These IV components can be associated with the expansion of the SNR that has disrupted the surrounding interstellar gas. The IV component at V = +92 km s −1 seen towards HD 37318 was detected only in the far-UV lines of Fe  and N , suggesting that it is composed mainly of warm and ionized gas. The two IV components observed towards HD 36665 were detected in Na , Ca , N , N , O  and Fe , indicating that it is composed of both neutral and ionized gas shells. Highly ionized gas was detected in the O λ 1032 Å absorption line at V ∼ +40 km s −1 towards both stars. This hot and highly ionized gas component is characterized by a columnn density ratio of N(C )/N(O ) < 0.27, which is consistent with that predicted by current models of evolved SNRs. However, we cannot preclude its origin in the interstellar medium in line-of-sight to S147. Column-density ratios of [Mg/Fe] [Na/Ca] have been derived for the IV gas components detected towards S147. Similar ratios have also been derived 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.

Discovery of an OB runaway star inside SNR S147

“…However, the AV measured directly towards S147 is much lower than the AV towards the stars beyond 1 kpc. Furthermore, two stars, HD 36665 and HD 37318, show highly shifted interstellar Ca II and Na I lines related to the SNR implying that these objects are background sources (Sallmen & Welsh 2004). Their distances based on the reported spectral types are closer to the Sun than HD 37424 is.…”

Supernova remnant S 147 and its associated neutron star(s)

“…The absorption spectrum of this star does not show high-velocity lines (Sallmen & Welsh 2004), that suggests that HD 37 367 is a foreground star and puts a lower limit on the distance to S 147 of ∼0.4 kpc.…”

Mapping the three-dimensional dust extinction towards the supernova remnant S147 – the S147 dust cloud

“…They claim that the SNR is evidently expanding into an inhomogeneous interstellar medium. Sallmen & Welsh (2004) have studied the interstellar Na i and Ca ii absorption lines in the high-resolution spectra of three stars at different distances in sight-lines towards S147. They find that two of the more distant stars, HD 36665 (d = 880 pc) and HD 37318 (d = 1380 pc), possess complex absorption features over intermediate velocities, while the nearest, foreground star, HD 37367 (d=360 pc), exhibits none of those features.…”