Molecular oxygen abundance is a key parameter in understanding the chemical network of the interstellar medium. We estimate the molecular oxygen column density and abundance for a sample of Galactic massive star formation regions based on observations from the Submillimiter Wave Astronomy Satellite (SWAS) survey. We obtained an averaged O_2_ spectrum based on this sample using the (SWAS) survey data (O_2_, 487.249GHz, N=3-1, J=3-2). No emission or absorption feature is seen around the supposed central velocity with a total integration time of t_total_=8.67x10^3^hr and an rms noise per channel of 1.45mK. Assuming a kinetic temperature T_kin_=30K, we derive the 3{sigma} upper limit of the O_2_ column density to be 3.3x10^15^cm^-2^, close to the lowest values reported in Galactic massive star formation regions in previous studies. The corresponding O_2_ abundance upper limit is 6.7x10^-8^, lower than all previous results based on SWAS observations and is close to the lowest reported value in massive star formation regions. On a galactic scale, our statistical results confirm a generally low O_2_ abundance for Galactic massive star formation regions. This abundance is also lower than results reported in extragalactic sources.
Cone search capability for table J/other/RAA/24.I5007/tabled1 (Massive Star Formation Regions Analyzed in the Paper)
