Herschel observations of extraordinary sources: Analysis of the HIFI 1.2 THz wide spectral survey toward orion KL. I. method

Journal Article · Sun Jun 01 04:00:00 EDT 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/787/2/112· OSTI ID:22356785

Crockett, Nathan R.; Bergin, Edwin A.; Neill, Justin L.; Favre, Cécile ^[1]; Schilke, Peter ^[2]; Lis, Dariusz C.; Emprechtinger, Martin; Phillips, Thomas G. ^[3]; Bell, Tom A.; Cernicharo, José; Esplugues, Gisela B. ^[4]; Blake, Geoffrey; Kleshcheva, Maria ^[5]; Gupta, Harshal; Pearson, John ^[6]; Lord, Steven ^[7]; Marcelino, Nuria ^[8]; McGuire, Brett A. ^[9]; Plume, Rene ^[10]; Van der Tak, Floris ^[11] ; others, and

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1. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
2. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln (Germany)
3. Cahill Center for Astronomy and Astrophysics 301-17, California Institute of Technology, Pasadena, CA 91125 (United States)
4. Centro de Astrobiología (CSIC/INTA), Laboratiorio de Astrofísica Molecular, Ctra. de Torrejón a Ajalvir, km 4, E-28850 Torrejón de Ardoz, Madrid (Spain)
5. Division of Geological and Planetary Sciences, California Institute of Technology, MS 150-21, Pasadena, CA 91125 (United States)
6. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States)
7. Infrared Processing and Analysis Center, California Institute of Technology, MS 100-22, Pasadena, CA 91125 (United States)
8. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
9. Division of Chemistry and Chemical Engineering, California Institute of Technology Pasadena, CA 91125 (United States)
10. Department of Physics and Astronomy, University of Calgary, 2500 University Drive NW, Calgary, AB T2N 1N4 (Canada)
11. SRON Netherlands Institute for Space Research, P.O. Box 800, 9700 AV Groningen (Netherlands)

We present a comprehensive analysis of a broadband spectral line survey of the Orion Kleinmann-Low nebula (Orion KL), one of the most chemically rich regions in the Galaxy, using the HIFI instrument on board the Herschel Space Observatory. This survey spans a frequency range from 480 to 1907 GHz at a resolution of 1.1 MHz. These observations thus encompass the largest spectral coverage ever obtained toward this high-mass star-forming region in the submillimeter with high spectral resolution and include frequencies >1 THz, where the Earth's atmosphere prevents observations from the ground. In all, we detect emission from 39 molecules (79 isotopologues). Combining this data set with ground-based millimeter spectroscopy obtained with the IRAM 30 m telescope, we model the molecular emission from the millimeter to the far-IR using the XCLASS program, which assumes local thermodynamic equilibrium (LTE). Several molecules are also modeled with the MADEX non-LTE code. Because of the wide frequency coverage, our models are constrained by transitions over an unprecedented range in excitation energy. A reduced χ{sup 2} analysis indicates that models for most species reproduce the observed emission well. In particular, most complex organics are well fit by LTE implying gas densities are high (>10{sup 6} cm{sup –3}) and excitation temperatures and column densities are well constrained. Molecular abundances are computed using H{sub 2} column densities also derived from the HIFI survey. The distribution of rotation temperatures, T {sub rot}, for molecules detected toward the hot core is significantly wider than the compact ridge, plateau, and extended ridge T {sub rot} distributions, indicating the hot core has the most complex thermal structure.

• OSTI ID: 22356785
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 787; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
DISTRIBUTION
EARTH ATMOSPHERE
EMISSION
EV RANGE
EXCITATION
GALAXIES
GHZ RANGE
HYDROGEN
LTE
MASS
MHZ RANGE
MOLECULES
NEBULAE
RESOLUTION
ROTATION
SPACE
SPECTROSCOPY
STARS
TELESCOPES