EDP Sciences
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Volume 381, Number 2, January II 2002
Page(s) 566 - 570
Section Diffuse matter in space
DOI http://dx.doi.org/10.1051/0004-6361:20011502

A&A 381, 566-570 (2002)
DOI: 10.1051/0004-6361:20011502

Molecular hydrogen gas at high-velocity associated with the Monoceros Loop SNR

B. Y. Welsh1, B. L. Rachford2 and J. Tumlinson2

1  Experimental Astrophysics Group, Space Sciences Laboratory, UC Berkeley, Berkeley, CA 94720, USA
2  Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309, USA

(Received 31 August 2001 / Accepted 15 October 2001 )

We present Far Ultraviolet Spectroscopic Explorer ( $\it FUSE$) observations of molecular hydrogen (H 2) gas observed at a high-velocity of $V_{\rm LSR} = +66$ km s -1 towards the star HD 47240 which lies just behind the Monoceros Loop Supernova Remnant at a distance of ~1800 pc. These absorption features have been detected in six lines of the J = 3 rotational level, with an equivalent molecular hydrogen column density of log  $N({\rm H}_{2}) = 14.10, \pm\,0.12$ cm -2. The observed data are best fit with a single excitation temperature, $T_{\rm ex}$, of ~1000 K, which when comparised to temperatures generally found for low J-levels is unusually high for interstellar H 2. The molecular fraction in this HV cloud has a very low value of log $f = -4.5\pm0.25$, which is similar to that found for HV clouds in the galactic halo.

Key words: ISM: supernova remnants -- ISM: molecules

Offprint request: B. Y. Welsh, bwelsh@ssl.berkeley.edu

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