Juan R. Pardo-Carrion
Abstract N. 8

G. Olofsson, L. Pagani, J. Tauber, P. Febvre, A. Deschamps, P. Encrenaz, H.G. Floren, S. George, B. Lecomte, B. Ljung, L. Nordh, J.R. Pardo, I. Peron, M. Sjokvist and K. Stegner; 1998

"Low Interstellar abundance of O2 confirmed by the PIROG 8 balloon experiment"

Astronomy and Astrophysics, 339, L81-L84.


Using a ballon-borne 60 cm telescope equipped with an SIS receiver we have searched for the 425 GHz molecular oxygen line in the NGC7538 and the W51 regions. The experiment was technically successful (confirmed by the detection of hte 13CO(4-3) line at 440 GHz), but we failed to detect emission from molecular oxygen. The infrarred upper limits of the O2/CO ratio are 0.04 and 0.05 (3sigma) for the two regions, which are the lowest upper limits so far determined for Galactic clouds.