Detection of sodium cyanide (NaCN) in IRC 10216

Turner, B. E.; Steimle, Timothy C.; Meerts, W. Leo

doi:10.1086/174043

Cited by 117 publications

(78 citation statements)

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“…KCN, KCl), or in dust grains. Similar to KCN, the NaCN molecule has indeed been detected in IRC +10 • 216 by Turner et al (1994). However, there is no clear indication as to the radial extent of the alkali metal-bearing molecules, i.e.…”

Section: Discussionmentioning

confidence: 99%

“…whether they still exist (against photodissociation) at the impact parameter of Star 6. In the case of NaCN, there is a large uncertainty, by a factor of 200, on its abundance, but if it forms in the outer envelope, up to 7% of Na can be in NaCN, according to Turner et al (1994). Little information exists on depletion of K and Na in carbonaceous grains.…”

Section: Discussionmentioning

confidence: 99%

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VLT/UVES and WHT/UES absorption spectroscopy of the circumstellar envelope of IRC + 10° 216 using background stars$^\star$

Kendall

Mauron

McCombie³

et al. 2002

A&A

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Abstract.A unique and novel set of observations has been undertaken to probe the circumstellar envelope (CSE) of the nearby (130 pc) carbon star IRC +10 • 216 using optical absorption spectroscopy towards background stars lying beyond the envelope. The primary aim of the observations is to search for diffuse band (DIB) carriers in the CSE, for which the mass-losing envelopes of carbon stars are a likely place of origin. Our principal target is a V = 16 G-type star located 37 from IRC +10 • 216 and was observed with VLT/UVES. A detailed model atmosphere and abundance analysis shows that it is somewhat metal-poor and has confirmed that it lies far beyond IRC +10 • 216. The circumstellar H+2H2 column density expected along the line of sight towards this target is relatively high, ∼2 × 10 21 cm −2 , and is large compared to that derived from the small interstellar extinction estimated in the zone of IRC +10 • 216 at b = +43 • , EB−V < 0.03 mag. The CSE is certainly detected in the K i resonance lines, which are centred at the heliocentric velocity of IRC +10 • 216 and have F W HM ∼ 30 km s −1 , consistent with twice the terminal expansion velocity of the circumstellar gas. The data show also that circumstellar Na i is very probably detected, as seen towards two background stars. The strongest DIB (6284Å) present in the UVES wavelength coverage is detected but very probably arises in the foreground ISM. No DIB is detected at 6614Å, or elsewhere. Overall, the data suggest that the DIB carriers, if present in the CSE, have a low abundance relative to H in the C-rich envelope of IRC +10 • 216, in comparison with this ratio in the ISM.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

VLT/UVES and WHT/UES absorption spectroscopy of the circumstellar envelope of IRC + 10° 216 using background stars$^\star$

Kendall

Mauron

McCombie³

et al. 2002

A&A

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“…The metal halides NaCl, KCl, AlCl, and AlF, and the cyanide NaCN are among the first metal-containing molecules detected in space (Cernicharo & Guélin 1987;Turner et al 1994). Metal-bearing molecules are rarely observed in the gas phase of the interstellar medium due to their large refractory character that make them to easily form solid condensates.…”

Section: Molecular Abundancesmentioning

confidence: 99%

Molecular abundances in the inner layers of IRC +10216

Agúndez

Fonfría

Cernicharo

et al. 2012

A&A

134

259

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Context. The inner layers of circumstellar envelopes around asymptotic giant branch stars are sites where a variety of processes such as thermochemical equilibrium, shocks induced by the stellar pulsation, and condensation of dust grains determine the chemical composition of the material that is expelled into the outer envelope layers and, ultimately, into interstellar space. Aims. We aim at studying the abundances, throughout the whole circumstellar envelope of the carbon star IRC +10216, of several molecules formed in the inner layers in order to constrain the different processes at work in such regions. Methods. Observations towards IRC +10216 of CS, SiO, SiS, NaCl, KCl, AlCl, AlF, and NaCN have been carried out with the IRAM 30-m telescope in the 80−357.5 GHz frequency range. A large number of rotational transitions covering a wide range of energy levels, including highly excited vibrational states, are detected in emission and serve to trace different regions of the envelope. Radiative transfer calculations based on the LVG formalism have been performed to derive molecular abundances from the innermost out to the outer layers. The excitation calculations include infrared pumping to excited vibrational states and inelastic collisions, for which up-to-date rate coefficients for rotational and, in some cases, ro-vibrational transitions are used. Results. We find that in the inner layers CS, SiO, and SiS have abundances relative to H 2 of 4 × 10 −6 , 1.8 × 10 −7 , and 3 × 10 −6 , respectively, and that CS and SiS have significant lower abundances in the outer envelope, which implies that they actively contribute to the formation of dust. Moreover, in the inner layers, the amount of sulfur and silicon in gas phase molecules is only 27% for S and 5.6% for Si, implying that these elements have already condensed onto grains, most likely in the form of MgS and SiC. Metal-bearing molecules lock up a relatively small fraction of metals, although our results indicate that NaCl, KCl, AlCl, AlF, and NaCN, despite their refractory character, are not significantly depleted in the cold outer layers. In these regions a few percent of the metals Na, K, and Al survive in the gas phase, either in atomic or molecular form, and are therefore available to participate in the gas phase chemistry in the outer envelope.

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“…Unlike metal-halogen species that are formed near the star photosphere, MgNC was found in a thin shell 15" in radius where many reactive species such as the carbon chain radicals C 5 H, C 6 H, C 7 H, and C 8 H, are also detected (Cernicharo et al 1986a,b;Guélin et al 1987;Cernicharo et al 1987a,b;Cernicharo & Guélin 1996;Guélin et al 1997). Just one year after the identification of MgNC, sodium cyanide was also detected in IRC+10216 by Turner et al (1994). MgNC has been also found towards the more evolved carbon star CRL2688 (Highberger et al 2003).…”

Section: Introductionmentioning

confidence: 97%

Laboratory and Astronomical Discovery of Hydromagnesium Isocyanide

Cabezas¹

2014

Proceedings of the 69th International Symposium on Molecular Spectroscopy

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We report on the detection of hydromagnesium isocyanide, HMgNC, in the laboratory and in the carbon rich evolved star IRC+10216. The J=1-0 and J=2-1 lines were observed in our microwave laboratory equipment in Valladolid with a spectral accuracy of 3 KHz. The hyperfine structure produced by the Nitrogen atom was resolved for both transitions. The derived rotational constants from the laboratory data are B 0 =5481.4333 (6) We have derived a column density for HMgNC of (6±2)×10 11 cm −2 . From the observed line profiles the molecule have to be produced produced in the layer where other metal-isocyanides have been already found in this source. The abundance ratio between MgNC and its hydrogenated variety, HMgNC, is ≃20.

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Detection of sodium cyanide (NaCN) in IRC 10216

Cited by 117 publications

References 0 publications

VLT/UVES and WHT/UES absorption spectroscopy of the circumstellar envelope of IRC + 10° 216 using background stars$^\star$

VLT/UVES and WHT/UES absorption spectroscopy of the circumstellar envelope of IRC + 10° 216 using background stars$^\star$

Molecular abundances in the inner layers of IRC +10216

Laboratory and Astronomical Discovery of Hydromagnesium Isocyanide

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