Large atomic oxygen abundance towards the molecular cloud L1689N

Caux, E.; Ceccarelli, C.; Castets, A.; Vastel, C.; Liseau, R.; Molinari, S.; Nisini, B.; Saraceno, P. and White, G. J. (1999). Large atomic oxygen abundance towards the molecular cloud L1689N. Astronomy & Astrophysics, 347 L1-L4.

URL: http://adsabs.harvard.edu/abs/1999A%26A...347L...1...

Abstract

We present spectroscopic ISO-LWS observations of the [OI] (63 μm and 145 μm), the [CII] (158 μm) and the H₂O (179 μm) lines towards the molecular cloud L1689N. From the observed ratio of the two [OI] lines, we deduce a mean gas temperature of (26±0.5) K, an H₂ density ≥ 3 x 10⁴ cm^-3 and an [OI] column density ≥ 5 x 10¹⁹ cm^-2. Combining these observations with previous CO observations, we obtain [OI]/[CO] ~ 50. This ratio implies that up to 98% of oxygen abundance is in atomic form in the gas phase. Furthermore, assuming all the gaseous carbon is locked into the CO, carbon has to be depleted by more than a factor 24. Finally, the upper limit derived for the H₂O (179 μm) line (3 x 10^-13 erg s^-1 cm^-2 ) implies that the water abundance in this region is less than 6 x 10^-7 with respect to H nuclei.

Viewing alternatives

Item Actions

Export

You can export this page using these formats