A spectral line survey of Orion KL in the bands 486-492 and 541-577 GHz with the Odin satellite - I. The observational data

TY - JOUR

T1 - A spectral line survey of Orion KL in the bands 486-492 and 541-577 GHz with the Odin satellite - I. The observational data

AU - Olofsson, A. O. H.

AU - Persson, C. M.

AU - Koning, N.

AU - Bergman, P.

AU - Bernath, P. F.

AU - Black, J. H.

AU - Frisk, U.

AU - Geppert, W.

AU - Hasegawa, T. I.

AU - Hjalmarson, A.

AU - Kwok, S.

AU - Larsson, B.

AU - Lecacheux, A.

AU - Nummelin, A.

AU - Olberg, M.

AU - Sandqvist, Aa.

AU - Wirstrom, E. S.

PY - 2007/12

Y1 - 2007/12

N2 - Aims. Spectral line surveys are useful since they allow identification of new molecules and new lines in uniformly calibrated data sets. The subsequent multi- transition analysis will provide improved knowledge of molecular abundances, cloud temperatures and densities, and may also reveal previously unsuspected blends of molecular lines, which otherwise may lead to erroneous conclusions. Nonetheless, large portions of the sub-millimetre spectral regime remain unexplored due to severe absorptions by H2O and O-2 in the terrestrial atmosphere. The purpose of the measurements presented here is to cover wavelength regions at and around 0.55 mm regions largely unobservable from the ground.Methods. Using the Odin astronomy/aeronomy satellite, we performed the first spectral survey of the Orion KL molecular cloud core in the bands 486-492 and 541-576 GHz with rather uniform sensitivity (22-25 mK baseline noise). Odin's 1.1 m size telescope, equipped with four cryo-cooled tuneable mixers connected to broad band spectrometers, was used in a satellite position-switching mode. Two mixers simultaneously observed-different 1.1 GHz bands using frequency steps of 0.5 GHz (25 h each). An on-source integration time of 20 h was achieved for most bands. The entire campaign consumed similar to 1100 orbits, each containing one hour of serviceable astro-observation.Results. We identified 280 spectral lines from 38 known interstellar molecules (including isotopologues) having intensities in the range 80 to 0.05 K. An additional 64 weak lines remain unidentified. Apart from the ground state rotational 1(1,0)-1(0,1) transitions of ortho-H2O, (H2O)-O-18 and H-2(17) O, the high energy 6(2,4)-7(1,7) line of para-H2O (E-u = 867 K) and the HDO(2(0,2)-1(1,1)) line have been observed, as well as the 1(0)-0(1) lines from NH3 and its rare isotopologue (NH3)-N-15. We suggest assignments for some unidentified features, notably the new interstellar molecules ND and SH-. Severe blends have been detected in the line wings of the H-2(18) O, H-2(17) O and (CO)-C-13 lines changing the true linewidths of the outflow emission.

AB - Aims. Spectral line surveys are useful since they allow identification of new molecules and new lines in uniformly calibrated data sets. The subsequent multi- transition analysis will provide improved knowledge of molecular abundances, cloud temperatures and densities, and may also reveal previously unsuspected blends of molecular lines, which otherwise may lead to erroneous conclusions. Nonetheless, large portions of the sub-millimetre spectral regime remain unexplored due to severe absorptions by H2O and O-2 in the terrestrial atmosphere. The purpose of the measurements presented here is to cover wavelength regions at and around 0.55 mm regions largely unobservable from the ground.Methods. Using the Odin astronomy/aeronomy satellite, we performed the first spectral survey of the Orion KL molecular cloud core in the bands 486-492 and 541-576 GHz with rather uniform sensitivity (22-25 mK baseline noise). Odin's 1.1 m size telescope, equipped with four cryo-cooled tuneable mixers connected to broad band spectrometers, was used in a satellite position-switching mode. Two mixers simultaneously observed-different 1.1 GHz bands using frequency steps of 0.5 GHz (25 h each). An on-source integration time of 20 h was achieved for most bands. The entire campaign consumed similar to 1100 orbits, each containing one hour of serviceable astro-observation.Results. We identified 280 spectral lines from 38 known interstellar molecules (including isotopologues) having intensities in the range 80 to 0.05 K. An additional 64 weak lines remain unidentified. Apart from the ground state rotational 1(1,0)-1(0,1) transitions of ortho-H2O, (H2O)-O-18 and H-2(17) O, the high energy 6(2,4)-7(1,7) line of para-H2O (E-u = 867 K) and the HDO(2(0,2)-1(1,1)) line have been observed, as well as the 1(0)-0(1) lines from NH3 and its rare isotopologue (NH3)-N-15. We suggest assignments for some unidentified features, notably the new interstellar molecules ND and SH-. Severe blends have been detected in the line wings of the H-2(18) O, H-2(17) O and (CO)-C-13 lines changing the true linewidths of the outflow emission.

KW - ISM : individual : objects : Orion KL

KW - ISM : lines and bands

KW - ISM : molecules

KW - line : identification

KW - submillimeter

KW - surveys

KW - SUBMILLIMETER ARRAY

KW - APERTURE SYNTHESIS

KW - MOLECULAR CLOUD

KW - TRANSITION

KW - REGION

KW - WATER

KW - SH

KW - IDENTIFICATION

KW - MILLIMETER

KW - NEBULA

U2 - 10.1051/0004-6361:20077229

DO - 10.1051/0004-6361:20077229

M3 - Article

VL - 476

SP - 791-U25

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

IS - 2

ER -