Identification of KCN in IRC+10216: Evidence for Selective Cyanide Chemistry - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical journal letters Année : 2010

Identification of KCN in IRC+10216: Evidence for Selective Cyanide Chemistry

Résumé

A new interstellar molecule, KCN, has been identified toward the circumstellar envelope of the carbon-rich asymptotic giant branch star, IRC+10216---the fifth metal cyanide species to be detected in space. Fourteen rotational transitions of this T-shaped, asymmetric top were searched for in the frequency range of 83-250 GHz using the Arizona Radio Observatory (ARO) 12 m Kitt Peak antenna, the IRAM 30 m telescope, and the ARO Submillimeter Telescope. Distinct lines were measured for 10 of these transitions, including the Ka = 1 and 2 asymmetry components of the J = 11 --> 10 and J = 10 --> 9 transitions, i.e., the K-ladder structure distinct to an asymmetric top. These data are some of the most sensitive astronomical spectra at lambda ~ 1 and 3 mm obtained to date, with 3sigma noise levels ~0.3 mK, made possible by new ALMA technology. The line profiles from the ARO and IRAM telescopes are consistent with a shell-like distribution for KCN with r outer ~ 15'', but with an inner shell radius that extends into warmer gas. The column density for KCN in IRC+10216 was found to be N tot ≈ 1.0 × 1012 cm-2 with a rotational temperature of T rot ~ 53 K. The fractional abundance was calculated to be f(KCN/H2) ~ 6 × 10-10, comparable to that of KCl. The presence of KCN in IRC+10216, along with MgNC, MgCN, NaCN, and AlNC, suggests that cyanide/isocyanide species are the most common metal-containing molecules in carbon-rich circumstellar gas.
Fichier non déposé

Dates et versions

hal-03742640 , version 1 (02-08-2022)

Identifiants

Citer

R. L. Pulliam, C. Savage, Marcelino Agúndez, José Cernicharo, Michel Guélin, et al.. Identification of KCN in IRC+10216: Evidence for Selective Cyanide Chemistry. The Astrophysical journal letters, 2010, 725, pp.L181-L185. ⟨10.1088/2041-8205/725/2/L181⟩. ⟨hal-03742640⟩
3 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More