J/A+A/618/A4 IRC+10216 as a spectroscopic laboratory (Cernicharo+, 2018)
IRC+10216 as a spectroscopic laboratory: improved rotational constants for
SiC2, its isotopologues, and Si2C.
Cernicharo J., Guelin M., Agundez M., Pardo J.R., Massalkhi S.,
Fonfria J.P., Velilla Prieto L., Quintana-Lacaci G., Marcelino N.,
Marka C., Navarro S., Kramer C.
<Astron. Astrophys. 618, A4 (2018)>
=2018A&A...618A...4C 2018A&A...618A...4C (SIMBAD/NED BibCode)
ADC_Keywords: Atomic physics ; Models ; Stars, carbon ; Spectroscopy
Keywords: molecular data - line: identification - stars: carbon -
circumstellar matter - stars: individual: IRC+10216 - astrochemistry
Abstract:
This work presents a detailed analysis of the laboratory and
astrophysical spectral data available for 28SiC2, 29SiC2,
30SiC2, Si13CC, and Si2C. New data on the rotational lines of
these species between 70 and 350GHz have been obtained with high
spectral resolution (195kHz) with the IRAM 30m telescope in the
direction of the circumstellar envelope IRC+10216. Frequency
measurements can reach an accuracy of 50kHz for features observed
with a good signal to noise ratio. From the observed astrophysical
lines and the available laboratory data new rotational and centrifugal
distortion constants have been derived for all the isotopologues of
SiC2, allowing to predict their spectrum with high accuracy in the
millimeter and submillimeter domains. Improved rotational and
centrifugal distortion constants have also been obtained for disilicon
carbide, Si2C. This work shows that observations of IRC+10216 taken
with the IRAM 30m telescope, with a spectral resolution of 195kHz,
can be used for any molecular species detected in this source to
derive, or improve, its rotational constants. Hence, IRC+10216 in
addition to be one the richest sources in molecular species in the
sky, can also be used as a state-of-the-art spectroscopy laboratory in
the millimeter and submillimeter domains.
Description:
Files contain the measured frequencies of the rotational lines of
different isotopologues of SiC2 and the main isotopologue of Si2C
derived from the fit to the observations along with values calculated
as described in the Appendix of the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea2.dat 67 421 Measured frequencies for the rotational lines
of SiC2
tablea5.dat 63 97 Measured rotational lines of 29SiC2
tablea8.dat 63 89 Measured rotational lines of 30SiC2
tablea11.dat 64 139 Measured rotational lines of Si13CC
tablea14.dat 65 149 Measured rotational lines of Si2C
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See also:
J/A+A/330/676 : IRC+10216 Silicon and sulfur chemistry (Willacy+ 1998)
J/ApJ/688/L83 : Detection of C5N- in IRC +10216 (Cernicharo+, 2008)
J/ApJS/177/275 : 1.3 and 2mm survey of IRC+10216 (He+, 2008)
J/ApJS/190/348 : 1mm spectral survey of IRC+10216 + VY CMa (Tenenbaum+, 2010)
J/ApJS/193/17 : Spectral-line survey of IRC+10216 at 293-355GHz (Patel+, 2011)
J/A+A/545/A12 : Chemistry of IRC+10216 inner wind modelled (Cherchneff, 2012)
J/A+A/574/A56 : IRC +10216 17.8GHz-26.3GHz spectrum (Gong+, 2015)
J/ApJ/806/L3 : CW Leo disilicon carbide (SiCSi) discovery (Cernicharo+, 2015)
J/A+A/601/A4 : IRC+10216 carbon chains mapped with ALMA (Agundez+, 2017)
J/A+A/606/A74 : IRC +10216 13.3GHz-18.5GHz spectrum (Zhang+, 2017)
Byte-by-byte Description of file: tablea*.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- J1 Quantum number J (upper level)
4- 5 I2 --- Ka1 Quantum number Ka (upper level)
7- 8 I2 --- Kc1 Quantum number Kc (upper level)
10- 11 I2 --- J0 Quantum number J (lower level)
13- 14 I2 --- Ka0 Quantum number Ka (lower level)
16- 17 I2 --- Kc0 Quantum number Kc (lower level)
19- 29 F11.3 MHz Fobs Observed frequency of the line
31- 36 F6.3 MHz e_Fobs Uncertainty (1 sigma) of the observed frequency
38- 48 F11.3 MHz Fcalc Calculated frequency of the line
50- 55 F6.3 MHz DeltaF Difference between observed and calculated
frequencies
57- 58 A2 --- Ref Reference (1)
60- 67 A8 --- Com Fit comments (2)
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Note (1): References as follows:
a1 = Rotational lines of SiC2 observed in the laboratory by Suenram et al.
(1989ApJ...342L.103S 1989ApJ...342L.103S)
a2 = Rotational lines of SiC2 observed in the laboratory by Gottlieb et al.
(1989ApJ...343L..29G 1989ApJ...343L..29G). Uncertainties for these lines from Mueller et al.
(2012JMoSp.271...50M 2012JMoSp.271...50M)
a3 = The 24 lines of SiC2 measured with the IRAM 30m telescope with
spectral resolution of 1MHz and used by Mueller et al.
(2012JMoSp.271...50M 2012JMoSp.271...50M).
New frequencies for these lines have been determined using the new IRAM
data (spectral resolution 0.195MHz)
a4 = 86 new lines of SiC2 between 70 and 355GHz observed with the IRAM 30m
telescope with a spectral resolution of 0.195MHz
a5 = The selected HIFI data are from Cernicharo et al. (2010A&A...521L...8C 2010A&A...521L...8C)
and Mueller et al. (2012JMoSp.271...50M 2012JMoSp.271...50M). Frequencies for these lines
have been remeasured again taken into account possible blends with
other features; some of the lines reported by Mueller et al.
(2012JMoSp.271...50M 2012JMoSp.271...50M) have been rejected due to its poor signal to
noise ratio. A total of 271 features between 480 and 1091GHz have been
included in the fit.
a6 = New HIFI lines.
b1 = Rotational lines of 29SiC2 observed in the laboratory by
Suenram et al. (1989ApJ...342L.103S 1989ApJ...342L.103S).
b2 = Rotational lines of 29SiC2 observed in the laboratory by
Kokkin et al. (2011ApJS..196...17K 2011ApJS..196...17K).
b3 = Lines reported by Cernicharo et al. (1986A&A...167L...9C 1986A&A...167L...9C,
1991A&A...246..213C 1991A&A...246..213C, 2000A&AS..142..181C 2000A&AS..142..181C) observed with the IRAM 30m
telescope with a spectral resolution of 1 MHz. New frequencies for
these lines have been determined using the new IRAM data (spectral
resolution 0.195MHz).
b4 = New lines of 29SiC2 between 70 and 355 GHz observed with the
IRAM 30m telescope with a spectral resolution of 0.195MHz.
c1 = Rotational lines of 30SiC2 observed in the laboratory by
Suenram et al. (1989ApJ...342L.103S 1989ApJ...342L.103S).
c2 = Rotational lines of 30SiC2 observed in the laboratory by
Kokkin et al. (2011ApJS..196...17K 2011ApJS..196...17K).
c3 = Lines reported by Cernicharo et al. (1986A&A...167L...9C 1986A&A...167L...9C,
1991A&A...246..213C 1991A&A...246..213C, 2000A&AS..142..181C 2000A&AS..142..181C) observed with the IRAM 30m
telescope with a spectral resolution of 1MHz. New frequencies for
these lines have been determined using the new IRAM data (spectral
resolution 0.195MHz).
c4 = New lines of 30SiC2 between 70 and 355GHz observed with the
IRAM 30m telescope with a spectral resolution of 0.195MHz.
d1 = Rotational lines of Si13CC observed in the laboratory by
Cernicharo et al. (1991A&A...246..213C 1991A&A...246..213C).
d2 = Rotational lines of Si13CC reported by Cernicharo et al.
(1991A&A...246..213C 1991A&A...246..213C, 2000A&AS...142..181C) observed with the IRAM 30m
telescope with a spectral resolution of 1MHz. New frequencies for
these lines have been determined using the new IRAM data (spectral
resolution 195kHz).
d3 = New lines of Si13CC between 70 and 355GHz observed with the IRAM 30m
telescope with a spectral resolution of 195kHz.
e1 = Rotational lines of Si2C observed in the laboratory by
McCarthy et al. (2015JPCLett...6..11).
e2 = Rotational lines of Si2C observed in the laboratory and reported by
Cernicharo et al. (2015ApJ...806L...3C 2015ApJ...806L...3C).
e3 = Observed lines of Si2C with the IRAM 30m telescope and reported by
Cernicharo et al. (2015ApJ...806L...3C 2015ApJ...806L...3C). Frequencies have been
determined again with the new data discussed in the text.
e4 = New lines of Si2C between 70 and 355GHz observed with the IRAM 30m
telescope with a spectral resolution of 195kHz.
Note (2): Comments as follows
D = Unresolved doublet. The central frequency of the doublet has been used
in the fit. A total of 71 doublets (SiC2) are reported in tablea2,
14 doublets (29SiC2) are reported in tablea5, 14 doublets (SiC2)
are reported in tablea8, and 10 doublets (Si13CC) in tablea11.
WI = Weak feature. Low precision frequency determination.
MB = Moderately blended with a feature. Fit still reliable.
BR = Blended with another feature of similar intensity in its red edge. Fit
still reliable.
SBR = Strong blending with another feature in its red edge. Fit is only
possible from the blue edge of the line.
SBB = Strong blending with another feature in its blue edge. Fit is only
possible from the red edge of the line.
BB = Blended with another feature of similar intensity in its blue edge.
Fit still reliable.
BRB = Blended with other features in its red and blue edges. Edges still
clearly visible and fit still reliable.
Sn = Data taken with the IRAM 30m telescope and with 195 kHz of spectral
resolution have been box smoothed to n channels. Data above 480GHz
are from HIFI/Herschel observations (Cernicharo et al.,
2010A&A...521L...8C 2010A&A...521L...8C, Mueller et al., 2012JMoSp.271...50M 2012JMoSp.271...50M). The nominal
spectral resolution for these data is 0.5MHz. Sn correspond to data
smoothed to a spectral resolution of 0.5nMHz.
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Acknowledgements:
Luis Velilla Prieto, l.velilla(at)csic.es
Guillermo Quintana-Lacaci, guillermo.q(at)csic.es
Sarah Massalkhi, sarah.massalkhi(at)csic.es
Jose Pablo Fonfria, jpablo.fonfria(at)csic.es
(End) Jose Pablo Fonfria [CSIC, Spain], Patricia Vannier [CDS] 11-Jun-2018