Search for HOOH in Orion
  Context: The abundance of key molecules determines the level of cooling that
is necessary for the formation of stars and planetary systems. In this context,
one needs to understand the details of the time dependent oxygen chemistry,
leading to the formation of molecular oxygen and water. Aims: We aim to
determine the degree of correlation between the occurrence of O2 and HOOH
(hydrogen peroxide) in star-forming molecular clouds. We first detected O2 and
HOOH in the rho Ophiuchi cloud (core A), we now search for HOOH in Orion
Molecular Cloud OMC A, where O2 has also been detected. Methods: We mapped a 3
arcmin times 3 arcmin region around Orion H2-Peak 1 with the Atacama Pathfinder
Experiment (APEX). In addition to several maps in two transitions of HOOH, viz.
219.17 GHz and 251.91 GHz, we obtained single-point spectra for another three
transitions towards the position of maximum emission. Results: Line emission at
the appropriate LSR-velocity (Local Standard of Rest) and at the level of
greater or equal to 4 sigma was found for two transitions, with lower S/N (2.8
- 3.5 sigma) for another two transitions, whereas for the remaining transition,
only an upper limit was obtained. The emitting region, offset 18 arcsec south
of H2-Peak 1, appeared point-like in our observations with APEX. Conclusions:
The extremely high spectral line density in Orion makes the identification of
HOOH much more difficult than in rho Oph A. As a result of having to consider
the possible contamination by other molecules, we left the current detection
status undecided.
