J/A+A/572/A44 Vibrationally excited vinyl cyanide in Orion-KL (Lopez+, 2014)
Laboratory characterization and astrophysical detection of vibrationally
excited states of vinyl cyanide in Orion-KL.
Lopez A., Tercero B., Kisiel Z., Daly A.M., Bermudez C., Calcutt H.,
Marcelino N., Viti S., Drouin B.J., Medvedev I.R., Neese C.F.,
Pszczolkowski L., Alonso J.L., Cernicharo J.
<Astron. Astrophys. 572, A44 (2014)>
=2014A&A...572A..44L 2014A&A...572A..44L
ADC_Keywords: Molecular clouds ; Atomic physics
Keywords: ISM: abundances - ISM: molecules - stars: formation -
line: identification - methods: laboratory: molecular -
radio lines: ISM
Abstract:
Laboratory characterization (18-1893 GHz) and astronomical detection
(IRAM-30m: 80-280GHz, Orion-KL) of CH2CHCN (vinyl cyanide) in its
ground and vibrationally excited states.
Improving the understanding of rotational spectra of vibrationally
excited vinyl cyanide with new laboratory data and analysis. The
laboratory results allow searching for these excited state transitions
in the Orion-KL line survey. Furthermore, rotational lines of CH2CHCN
contribute to the understanding of the physical and chemical
properties of the cloud.
Laboratory measurements of CH2CHCN made on several different
frequency-modulated spectrometers were combined into a single
broadband 50-1900GHz spectrum and its assignment was confirmed by
Stark modulation spectra recorded in the 18-40GHz region and by
ab-initio anharmonic force field calculations. For analyzing the
emission lines of vinyl cyanide detected in Orion-KL we used the
excitation and radiative transfer code (MADEX) at LTE conditions.
Detailed characterisation of laboratory spectra of CH_2CHCN in 9
different excited vibrational states (v11=1, v15=1, v11=2,
v10=1⟺(v11=1,v15=1), v11=3/v15=2/v14=1,
(v11=1,v10=1)⟺(v11=2, v15=1), v9$=1,
(v11=1,v15=2)⟺(v10=1, v15=1)⟺(v11=1,v14=1), and
v11=4) and detection of transitions in the v11=2 and v11=3
states for the first time in Orion-KL, and of those in the
v10=1⟺(v11=1,v15=1) dyad of states for the first time in
space. The rotational transitions of the ground state of this molecule
emerge from four cloud components of hot core nature which trace the
physical and chemical conditions of high mass star forming regions in
the Orion-KL Nebula. The lowest energy vibrationally excited states of
vinyl cyanide such as v11=1 (at 328.5K), v15=1 (at 478.6K),
v11=2 (at 657.8K), the v10=1⟺(v11=1,v15=1) dyad (at
806.4/809.9K), and v11=3 (at 987.9K) are populated under warm and
dense conditions, so they probe the hottest parts of the Orion-KL
source. The vibrational temperatures derived for the v11=1, v11=2,
and v15=1 states are 252±76K, 242±121K, and 227±68K,
respectively; all of them close to the mean kinetic temperature of the
hot core component (210K). The total column density of CH2CHCN in
the ground state is (3.0±0.9)x1015cm-2. We report the detection
of methyl isocyanide (CH3NC) for the first time in Orion-KL and a
tentative detection of vinyl isocyanide (CH2CHNC) and give column
density ratios between the cyanide and isocyanide isomers obtaining a
N(CH3NC)/N(CH3CN) ratio of 0.002.
Laboratory characterisation of many previously unassigned
vibrationally excited states of vinyl cyanide at microwave to THz
frequencies allowed us to detect these molecular species in Orion-KL.
Column density and rotational and vibrational temperatures for
CH2CHCN in their ground and excited states, as well as for the
isotopologues, have been constrained by means of a sample of more than
1000 lines in this survey.
Description:
Observed (by Gaussian fits to the observed line profile) and
laboratory line parameters for the ground state, the vibrationally
excited states, and the 13C-vinyl cyanide isotopologues are
presented. Spectroscopic constants were derived from a fit to the
lines reported by diverse authors with the MADEX code and dipole
moment values have been implemented in MADEX to obtain the predicted
frequencies and the spectroscopic line parameters. For each CH2CHCN
specie line transition, predicted frequency, line strength, upper
level energy, observed radial velocities relative to the local system
rest (assuming a vLSR of 5km/s), line width, main beam temperature,
and area of the line are given. Rotational lines that are not strongly
overlapped with lines from other species are displayed.
Objects:
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RA (ICRS) DE Designation(s)
------------------------------------------------
05 35 14.16 -05 22 21.5 Orion-KL = Ori-KL
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
gs.dat 108 792 *Emission lines of CH2CHCN ground state
gs_b.dat 88 23 *Emission b-type lines of CH2CHCN in its
ground state
v11.dat 108 546 *Emission lines of CH2CHCN v11=1
2v11.dat 108 421 *Emission lines of CH2CHCN v11=2
3v11.dat 108 377 *Emission lines of CH2CHCN v11=3
v15.dat 108 480 *Emission lines of CH2CHCN v15=1
v10-v15.dat 88 735 *Emission lines of vinyl isocyanide
(CH2CHNC) v10=1⟺v11=1,v15=1
13c.dat 88 343 *Emission lines of 13CH2CHCN, CH213CHCN and
CH2CH13CN isotopologues in its ground state
iso.dat 88 88 *Emission lines of vinyl isocyanide (CH2CHNC)
notes.dat 55 444 Individual notes
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Note on *.dat: present in the spectral scan of the Orion-KL from the
radio-telescope of IRAM 30-m.
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See also:
J/AJ/120/1426 : Chandra sources in ONC + BN-KL (Garmire+, 2000)
J/ApJS/156/127 : 350µm molecular line survey of Orion KL (Comito+, 2005)
J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)
J/A+A/559/A51 : HC3N in Orion KL (Esplugues+, 2013)
Byte-by-byte Description of file: gs_b.dat v10-v15.dat 13c.dat iso.dat
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Bytes Format Units Label Explanations
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1 A1 --- Iso [ABC] Isotope identification (13c.dat only) (1)
3- 25 A23 --- Trans Line transition (2)
27- 36 F10.3 MHz Fpred Predicted frequency in the laboratory
37 A1 --- n_Fpred [+] +: blended with the previous one
39- 43 F5.2 --- Sij Line strength
45- 50 F6.1 cm-1 Eu Upper level energy
52- 55 F4.2 km/s vLSR ? Observed radial velocities relatives
56 A1 --- n_vLSR [h] h: hole in the observed spectrum
57- 67 A11 --- Note Notes, within the table, in notes.dat file
69- 76 F8.1 MHz Fobs ?=- Observed centroid frequency assuming a
vLSR of 5km/s
79- 83 F5.3 K Tmb.o ?=- Observed mean beam temperature
85- 88 F4.2 K Tmb.m ?=- Mean beam temperature obtained with the model
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Note (1): Isotope codes as follows:
A = Detected lines of 13CH2CHCN
B = Detected lines of CH213CHCN
C = Detected lines of CH2CH13CN
Note (2): Line transition as (JKa,Kc-J'K'a,K'c), except for
v10-v15.dat (JKa,Kc,v-J'K'a,K'c,v').
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Byte-by-byte Description of file: v11.dat 2v11.dat 3v11.dat gs.dat v15.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- Trans Line transition (JKa,Kc-J'K'a,K'c)
27- 36 F10.3 MHz Fpred Predicted frequency in the laboratory
37 A1 --- n_Fpred [+] +: blended with the previous one
39- 43 F5.2 --- Sij ? Line strength
44- 45 A2 --- n_Sij [Wc Nc] Wide (Wc) for Narric (Nc) component,
only for gs.dat
47- 52 F6.1 cm-1 Eu ?=- Upper level energy
54- 58 F5.2 km/s vLSR ? Observed radial velocity relative to the
local system rest
60- 63 F4.2 km/s e_vLSR ? rms uncertainty on vLSR
64 A1 --- f_vLSR [h*] hole in the observed spectrum(h), or
high noise level (*)
65- 76 A12 --- Note Notes, within the table, in notes.dat file
78- 82 F5.2 km/s Dv ? Line width
84- 87 F4.2 km/s e_Dv ? Line width
90- 93 F4.2 K Tmb ?=- Mean beam temperature
96 I1 --- n_Tmb [2]? 2: peak channel line intensity
99-103 F5.2 K.km/s Area ? Area of the line
105-108 F4.2 K.km/s e_Area ? rms uncertainty on Area
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Byte-by-byte Description of file: notes.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Table Table name
12- 13 I2 --- Note Note number, within the table
15 A1 --- --- [=]
17- 55 A39 --- Text Text of the note
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Acknowledgements:
Alicia Lopez, lopezja(at)cab.inta-csic.es
(End) Patricia Vannier [CDS] 17-Jul-2014