J/ApJ/806/L3 Disilicon carbide (SiCSi) discovery in CW Leo (Cernicharo+, 2015)
Discovery of SiCSi in IRC+10216: a missing link between gas and dust carriers
of Si-C bonds.
Cernicharo J., McCarthy M.C., Gottlieb C.A., Agundez M., Velilla Prieto L.,
Baraban J.H., Changala P.B., Guelin M., Kahane C., Martin-Drumel M.A.,
Patel N.A., Reilly N.J., Stanton J.F., Quintana-Lacaci G., Thorwirth S.,
Young K.H.
<Astrophys. J., 806, L3 (2015)>
=2015ApJ...806L...3C 2015ApJ...806L...3C (SIMBAD/NED BibCode)
ADC_Keywords: Stars, carbon ; Atomic physics
Keywords: astrochemistry; stars: AGB and post-AGB; stars: carbon;
stars: individual: (IRC +10216)
Abstract:
We report the discovery in space of a disilicon species, SiCSi, from
observations between 80 and 350GHz with the IRAM 30m radio telescope.
Owing to the close coordination between laboratory experiments and
astrophysics, 112 lines have now been detected in the carbon-rich star
CW Leo. The derived frequencies yield improved rotational and
centrifugal distortion constants up to sixth order. From the line
profiles and interferometric maps with the Submillimeter Array, the
bulk of the SiCSi emission arises from a region of 6" in radius. The
derived abundance is comparable to that of SiC2. As expected from
chemical equilibrium calculations, SiCSi and SiC2 are the most
abundant species harboring a Si-C bond in the dust formation zone and
certainly both play a key role in the formation of SiC dust grains.
Description:
In the course of searches for new molecules we have covered a large
fraction of the 3, 2, 1, and 0.8mm spectrum of IRC+10216 with a high
sensitivity using the 30m IRAM radio telescope. In the 3mm window, the
data acquired during the last 30 years cover the 80-116GHz domain with
very high sensitivity (1-3mK).
Objects:
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RA (ICRS) DE Designation(s)
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09 47 57.41 +13 16 43.6 IRC +10216 = V* CW Leo
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 134 Observed lines of SiCSi in the laboratory and
in IRC+10216
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See also:
J/A+A/574/A56 : IRC +10216 17.8GHz-26.3GHz spectrum (Gong+, 2015)
J/A+A/545/A12 : Chemistry of IRC+10216 inner wind modelled (Cherchneff, 2012)
J/ApJS/193/17 : Spectral-line survey of IRC+10216 at 293-355GHz (Patel+, 2011)
J/ApJS/190/348 : 1mm spectral survey of IRC+10216 + VY CMa (Tenenbaum+, 2010)
J/ApJS/186/406 : 350um polarimetry from CSO (Dotson+, 2010)
J/ApJS/182/143 : SCUPOL Legacy polarimetry of SCUBA (Matthews+, 2009)
J/ApJS/177/275 : 1.3 and 2mm survey of IRC+10216 (He+, 2008)
J/ApJ/688/L83 : Detection of C5N- in IRC +10216 (Cernicharo+, 2008)
J/A+A/431/773 : CHARM2, an updated of CHARM catalog (Richichi+, 2005)
J/ApJS/154/673 : COBE DIRBE Point Source Catalog (Smith+, 2004)
J/A+AS/142/181 : 2mm molecular line survey of IRC+10 216 (Cernicharo+, 2000)
J/A+A/330/676 : IRC+10216 Silicon and sulfur chemistry (Willacy+ 1998)
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 [1/48] Upper J level
4 I1 --- Ka1 [0/5] Upper Ka level
6- 7 I2 --- Kc1 [1/47] Upper Kc level
9- 10 I2 --- J0 [0/47] Lower J level
12 I1 --- Ka0 [0/4] Lower Ka level
14- 15 I2 --- Kc0 [0/46] Lower Kc level
17- 27 F11.4 MHz nuObs [6718.9/350483] Observed frequency
29- 33 F5.3 MHz e_nuObs [0.002/2] The 1σ uncertainty in nuObs
35- 39 F5.3 K.km/s intTA* [0.05/0.93]? Integrated antenna temperature
41- 45 F5.3 K.km/s e_intTA* [0.006/0.1]? The 1σ uncertainty in intTA*
47- 56 F10.3 MHz nuPre [6718.9/350484.1] Predicted frequency
58- 62 F5.3 MHz e_nuPre [0.001/1] The 1σ uncertainty in nuPre
64- 68 F5.1 K Eup [3.3/484.5] Upper level energy
70- 75 F6.3 --- Sul [0.5/33.6] Line strength
77- 80 F4.1 mK sigma [0.6/16.7]? The 1σ observation noise
81 A1 --- f_sigma [l] l: laboratory data
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 21-Oct-2015