2015A&A...581A..48G


C.D.S. - SIMBAD4 rel 1.7 - 2020.03.29CEST12:09:38

2015A&A...581A..48G - Astronomy and Astrophysics, volume 581A, 48-48 (2015/9-1)

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. and KLEIN B.

Abstract (from CDS):

The nearby Orion Kleinmann-Low nebula is one of the most prolific sources of molecular line emission. It has served as a benchmark for spectral line searches throughout the (sub)millimeter regime. The main goal is to systematically study the spectral characteristics of Orion KL in the λ∼1.3cm band. We carried out a spectral line survey with the Effelsberg-100 m telescope toward Orion KL. It covers the frequency range between 17.9GHz and 26.2GHz, i.e., the radio ``K band''. We also examined ALMA maps to address the spatial origin of molecules detected by our 1.3cm line survey. In Orion KL, we find 261 spectral lines, yielding an average line density of about 32 spectral features per GHz above 3σ (a typical value of 3σ is 15mJy). The identified lines include 164 radio recombination lines (RRLs) and 97 molecular lines. The RRLs, from hydrogen, helium, and carbon, stem from the ionized material of the Orion Nebula, part of which is covered by our beam. The molecular lines are assigned to 13 different molecular species including rare isotopologues. 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 (J>K) 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), but not in other SO2 transitions, possibly suggesting the presence of a maser line. Column densities and fractional abundances relative to H2 are estimated for 12 molecules with local thermodynamic equilibrium (LTE) methods. Rotational diagrams of non-metastable 14NH3 transitions with J=K+1 to J=K+4 yield different results; metastable (J=K) 15NH3 is found to have a higher excitation temperature than non-metastable 15NH3, also indicating that they may trace different regions. Elemental and isotopic abundance ratios are also estimated: He/H=(8.7±0.7)% derived from the ratios between helium RRLs and hydrogen RRLs; 12C/13C=63±17 from 12CH3OH/13CH3OH; 14N/15N=100±51 from 14NH3/15NH3; and D/H=(8.3±4.5)x10–3 from NH2D/NH3. The dispersion of the He/H ratios derived from Hα/Heα pairs to Hδ/Heδ 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 that neglects 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.

Abstract Copyright:

Journal keyword(s): astrochemistry - ISM: individual objects: Orion KL - ISM: molecules - radio lines: ISM - surveys

VizieR on-line data: <Available at CDS (J/A+A/581/A48): list.dat orion-kl.fits>

Status at CDS:  

Simbad objects: 33

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Number of rows : 33

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 Barnard 1 MoC 03 33 16.3 +31 07 51           ~ 253 0
2 QSO B0420-0127 QSO 04 23 15.80072776 -01 20 33.0654034   17.50 17.00 16.28   ~ 1033 3
3 TMC-1 MoC 04 41 45.9 +25 41 27           ~ 1341 0
4 RAFGL 618 pA* 04 42 53.6245215366 +36 06 53.397219192   16.32   12.59   C-rich 951 0
5 LDN 1544 DNe 05 04 16.6 +25 10 48           ~ 665 0
6 LHA 120-N 113 HII 05 13 21.7 -69 21 33           ~ 96 1
7 NAME LMC G 05 23 34.6 -69 45 22     0.4     ~ 14610 1
8 MLLA 602 * 05 35 13.9700 -05 22 31.900           ~ 53 0
9 [WLQ2014] MM6 cor 05 35 14.10 -05 22 27.4           ~ 3 0
10 [WLQ2014] MM5 cor 05 35 14.11 -05 22 28.9           ~ 3 0
11 V* V2254 Ori Or* 05 35 14.113 -05 22 22.73           B 282 2
12 [GD77] B IR 05 35 14.15 -05 22 37.4           ~ 30 0
13 NAME Orion-KL SFR 05 35 14.16 -05 22 21.5           ~ 1976 1
14 [RLK73] IRc 6 IR 05 35 14.18 -05 22 26.7           ~ 36 0
15 [GD77] A IR 05 35 14.19 -05 22 34.0           ~ 58 0
16 [FW2011] J053514.278-052230.647 IR 05 35 14.278 -05 22 30.65           ~ 68 0
17 [WLQ2014] MM4 cor 05 35 14.35 -05 22 30.9           ~ 8 0
18 NAME Ori N Y*O 05 35 14.35371 -05 22 32.8820           ~ 102 0
19 JCMTSE J053514.4-052232 Y*? 05 35 14.488 -05 22 32.10           ~ 46 0
20 [RLK73] IRc 2 IR 05 35 14.51548 -05 22 30.5943           ~ 568 1
21 M 42 HII 05 35 17.3 -05 23 28           ~ 3693 0
22 NAME Orion Bright Bar reg 05 35 22.30 -05 24 33.0           ~ 706 0
23 QSO B0605-0834 QSO 06 07 59.69923743 -08 34 49.9781718     18.5 17.70   ~ 389 1
24 2C 553 QSO 06 27 10.1 -05 53 06           ~ 148 1
25 IRC +10216 C* 09 47 57.40632 +13 16 43.5648     10.96     C9,5e 2120 0
26 NGC 4945 Sy2 13 05 27.279 -49 28 04.44   9.31 14.40 7.55   ~ 1247 2
27 3C 286 Sy1 13 31 08.2885060664 +30 30 32.960825108   17.51 17.25     ~ 3670 1
28 IC 4553 SyG 15 34 57.22396 +23 30 11.6084   14.76 13.88     ~ 2656 4
29 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11305 0
30 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 1885 1
31 [WBN74] W 51 IRS 2 SFR 19 23 40.05 +14 31 07.1           ~ 252 0
32 W 51 SNR 19 23 50 +14 06.0           ~ 1132 1
33 NGC 7027 PN 21 07 01.8 +42 14 10   9.1 10.9     ~ 2312 1

    Equat.    Gal    SGal    Ecl

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2020.03.29-12:09:38

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