J/A+A/581/A48 1.3cm line survey toward Orion KL (Gong+, 2015)
A 1.3 cm line survey toward Orion KL.
Gong Y., Henkel C., Thorwirth S., Spezzano S., Menten K.M., Walmsley C.M.
Wyrowski F., Mao R.Q., Klein B.
<Astron. Astrophys. 581, A48 (2015)>
=2015A&A...581A..48G 2015A&A...581A..48G
ADC_Keywords: Interstellar medium; Spectroscopy; YSOs; Surveys; Radio lines
Keywords: astrochemistry - ISM: individual (Orion KL) - ISM: molecules -
radio lines: ISM - surveys
Abstract:
Orion KL has served as a benchmark for spectral line searches
throughout the (sub)millimeter regime. The main goal is to
systematically study spectral characteristics of Orion KL in the 1.3cm
band. We carried out a spectral line survey (17.9GHz to 26.2GHz) with
the Effelsberg-100m telescope towards Orion KL. We find 261 spectral
lines, yielding an average line density of about 32 spectral features
per GHz above 3 sigma. The identified lines include 164 radio
recombination lines (RRLs) and 97 molecular lines. A total of 23
molecular transitions from species known to exist in Orion KL are
detected for the first time in the interstellar medium. Non-metastable
15NH3 transitions are detected in Orion KL for the first time.
Based on the velocity information of detected lines and the ALMA
images, the spatial origins of molecular emission are constrained and
discussed. A narrow feature is found in SO2 (81,7-72,6),
possibly suggesting the presence of a maser line. Column densities and
fractional abundances relative to H2 are estimated for 12 molecules
with LTE methods. Rotational diagrams of non-metastable 14NH3
transitions with J=K+1 to J=K+4 yield different results; metastable
15NH3 is found to have a higher excitation temperature than
non-metastable 15NH3, indicating that they may trace different
regions. Elemental and isotopic abundance ratios are estimated:
12C/13C=63±17, 14N/15N=100±51, D/H=0.0083±0.0045. The
dispersion of the He/H ratios derived from Halpha/Healpha_ pairs to
Hdelta/Hedelta pairs is very small, which is consistent with
theoretical predictions that the departure coefficients bn factors for
hydrogen and helium are nearly identical. Based on a non-LTE code
neglecting excitation by the infrared radiation field and a likelihood
analysis, we find that the denser regions have lower kinetic
temperature, which favors an external heating of the Hot Core.
Description:
The observations of the 1.3cm line survey toward Orion KL were
observed with the Effelsberg 100-m telescope. The intensity of the
spectra is in units of Jy for this fits file. The spectra have 140001
channels and a channel spacing of 61kHz, covering the entire 1.3cm K
band wavelength range. The rest frequency at the 70001st channel is
22000MHz.
Objects:
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RA (2000) DE Designation(s)
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05 35 14.16 -05 22 21.5 Orion KL = Name Orion-KL
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 128 1 Information of fits spectrum
orion-kl.fits 2880 197 Fits spectrum
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See also:
J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)
J/A+A/559/A51 : HC3N in Orion KL (Esplugues+, 2013)
J/A+A/572/A44 : Vibrationally excited vinyl cyanide in Orion-KL (Lopez+, 2014)
J/AJ/149/162 : GBT 67-93.6GHz spectral line survey of Orion-KL (Frayer+ 2015)
J/ApJ/769/48 : Water maser in Orion-KL with Herschel (Neufeld+, 2013)
J/ApJ/777/120 : cm to submm spectra of H2C=CH-CH2NC (Haykal+, 2013)
J/ApJ/779/119 : HCOOCH2D detection in Orion KL (Coudert+, 2013)
J/ApJS/156/127 : 350µm molecular line survey of Orion KL (Comito+, 2005)
J/ApJS/215/25 : Methyl formate (HCOOCH3) observations (Favre+, 2014)
Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right ascension (J2000)
10- 18 F9.5 deg DEdeg Declination (J2000)
20- 25 I6 --- Nx Number of wavelengths
27- 45 A19 "datime" Obs.Date Observation date (YYYY-MM-DDThh:mm:ss.sss)
47- 51 F5.2 GHz nu.min [16.27] Lower value of frequency interval
53- 57 F5.2 GHz nu.max [26.27] Upper value of frequency interval
59- 65 F7.4 kHz dnu Spectral resolution
67- 69 I3 Kibyte Size Size of the fits file
71- 83 A13 --- FileName Name of the fits file
85-128 A44 --- Title Title of the file
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Acknowledgements:
Yan Gong, ygong(at)pmo.ac.cn
(End) Patricia Vannier [CDS] 30-Jun-2015