J/ApJ/784/L7 CH3CH2SH detection in Orion KL (Kolesnikova+, 2014)
Spectroscopic characterization and detection of ethyl mercaptan in Orion.
Kolesnikova L., Tercero B., Cernicharo J., Alonso J.L., Daly A.M.,
Gordon B.P., Shipman S.T.
<Astrophys. J., 784, L7 (2014)>
=2014ApJ...784L...7K 2014ApJ...784L...7K (SIMBAD/NED BibCode)
ADC_Keywords: Interstellar medium ; Atomic physics ; Line Profiles ;
Spectra, millimetric/submm ; Radio lines
Keywords: ISM: abundances - ISM: individual objects (Orion KL) -
ISM: molecules - line: identification
Abstract:
New laboratory data of ethyl mercaptan, CH3CH2SH, in the
millimeter- and submillimeter-wave domains (up to 880GHz) provided
very precise values of the spectroscopic constants that allowed the
detection of gauche-CH3CH2 SH toward Orion KL. This identification
is supported by 77 unblended or slightly blended lines plus no missing
transitions in the range 80-280GHz. A detection of methyl mercaptan,
CH3SH, in the spectral survey of Orion KL is reported as well. Our
column density results indicate that methyl mercaptan is ≃5 times
more abundant than ethyl mercaptan in the hot core of Orion KL.
Description:
Rotational spectra in the 8.7-26.5GHz region were taken at a
temperature of -15°C and a pressure of 6mTorr with a waveguide
chirped-pulse Fourier transform microwave spectrometer at New College
of Florida. Peaks in the frequency-domain spectrum had an FWHM of
∼800kHz and so the uncertainty on the line center was set to 80kHz.
Rotational spectra in the millimeter (60-300GHz) and
submillimeter-wave (500-590GHz, 625-660GHz, and 835-880GHz) regions
were recorded at a pressure of approximately 15mTorr by a recently
constructed millimeter-wave spectrometer at the University of
Valladolid.
Five observing sessions (from 2004 September to 2007 January) were
required for completing a molecular line survey in all frequencies
available with the A, B, C, and D receivers (80-115.5, 130-178,
197-281GHz) of the IRAM 30m telescope toward Orion KL (IRc2 source at
α(J2000)=5h35m14.5s, δ(J2000)=-5°22'30.0'').
System temperatures, image side band rejections, and half power beam
widths were in the ranges 100-800K, 27-13dB, and 29''-9'',
respectively, from lower to higher frequencies.
The measured transitions are given in the Table2.
Objects:
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RA (ICRS) DE Designation(s)
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05 35 14.16 -05 22 21.5 Orion KL = NAME BN Nebula
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 117 5013 *Laboratory measurements and astronomically
detected lines of ethyl mercaptan
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Note on table2.dat: This table gives the laboratory measurements and emission
lines of gauche- and trans-CH3CH2SH present in the Orion KL survey. All the
transition frequencies included in the least-squares analysis were weighted
inversely proportionally to the second power of their estimated uncertainties.
The unresolved pairs of the asymmetry splitting were always included as two
overlapped transitions and fitted to their intensity weighted averages.
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See also:
J/A+A/572/A44 : Vibrationally excited vinyl cyanide in Orion-KL (Lopez+, 2014)
J/ApJ/779/119 : HCOOCH2D detection in Orion KL (Coudert+, 2013)
J/ApJ/770/L13 : Detection of CH3COOCH3 in Orion (Tercero+, 2013)
J/ApJ/768/81 : Ethyl cyanide, CH3CH2CN, vibrational states (Daly+, 2013)
J/A+A/559/A47 : Sgr B2(N) and Sgr B2(M) IRAM 30m line survey (Belloche+, 2013)
J/A+A/532/A32 : HCOOCH3 map of Orion-KL (Favre+, 2011)
J/ApJ/714/1120 : Rotational spectrum and DCOOCH3 in Orion (Margules+, 2010)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- J1 [1/89] Upper J quantum number (J')
4- 5 I2 --- Ka1 [0/25] Upper Ka quantum number (K'a)
7- 8 I2 --- Kc1 [0/89] Upper Kc quantum number (K'c)
10 I1 --- v1 [0/1]? Upper v quantum number (v')
12- 13 I2 --- J0 [0/88] Lower J quantum number (J")
15- 16 I2 --- Ka0 [0/25] Lower Ka quantum number (K"a)
18- 19 I2 --- Kc0 [0/88] Lower Kc quantum number (K"c)
21 I1 --- v0 [0/1]? Lower v quantum number (v")
23- 33 F11.4 MHz Flab [8716.5/879717.2] Laboratory measured frequency
35 A1 --- f_Flab [ab] Flag on Flab (a=literature data,
b=predicted frequency) (1)
37- 44 F8.5 MHz O-C [-3.8/1.3]? Laboratory minus predicted
frequency
46 A1 --- C [GT] Corresponding conformer (G=gauche,
or T=trans)
48- 54 A7 --- f_C Flag on C (34S)
56- 60 F5.1 K Eup [22.8/555.2]? Upper level energy Eu
62- 67 F6.2 --- Sij [3/122]? Line strength Sij
69- 76 F8.1 MHz Fobs [98918.2/280538]? Observed frequency (2)
78- 79 A2 --- f_Fobs Flag on Fobs (dg=blended with previous
line) (3)
81- 84 F4.2 K Tmb [0.02/0.77]? Main beam temperature Tmb
86-117 A32 --- Blend Blended transition(s) with other molecules
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Note (1): Flag on measured frequency defined as follows:
a = Data taken from Quade et al. (1975, JCP, 62, 3864);
b = Predicted frequency.
Note (2): In the line survey of Orion assuming a vLSR of 5km/s.
Note (3): Flag on observed frequency defined as below:
dg = Blended with previous line;
c = In the blue wing of a HCOOH line;
d = In the red wing of a H2C34S line;
e = In the red wing of a U line.
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History:
From electronic version of the journal
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 02-Aug-2016