TY - JOUR
T1 - More metal cyanide species
T2 - Detection of A1NC (X1 ∑ +) Toward IRC + 10216
AU - Ziurys, L. M.
AU - Savage, C.
AU - Highberger, J. L.
AU - Apponi, A. J.
AU - Guélin, M.
AU - Cernicharo, J.
N1 - Funding Information:
This research is supported by NSF grant AST 98-20576. C. S. thanks NASA for a graduate fellowship, and J. L. H. acknowledges NRAO for graduate support.
PY - 2002/1/1
Y1 - 2002/1/1
N2 - A new metal-containing species, A1NC, has been detected toward the circumstellar envelope of the late-type carbon star IRC + 10216, using the IRAM 30 m telescope. The J = 11 → 10, 12 → 11, and 13 → 12 rotational transitions at 2 mm and the J = 18 → 17 and J = 21 → 20 transitions at 1.2 mm of this linear, closed-shell molecule were observed in this object. The line profiles appear U-shaped, indicating a source ≃20″, and the horn-to-center ratios suggest a shell-like distribution. In contrast, the other two Al-bearing molecules previously detected, A1F and A1C1, exist exclusively near the stellar photosphere. Modeling of the detected transitions, assuming a spherical-shell distribution, indicates a column density of Ntot ∼9 × 1011 cm-2 and a fractional abundance relative to H2 of ∼ 3 × 10-10 for A1NC. A rotational temperature of Trot ∼ 60 K was also derived for this molecule, suggesting that shock waves may be synthesizing A1NC in the outer envelope. This species is the fourth metal cyanide/isocyanide compound discovered in this object, along with MgNC, MgCN, and NaCN. These data suggest that cyanide/isocyanide species are the major molecular carriers of metals in circumstellar gas.
AB - A new metal-containing species, A1NC, has been detected toward the circumstellar envelope of the late-type carbon star IRC + 10216, using the IRAM 30 m telescope. The J = 11 → 10, 12 → 11, and 13 → 12 rotational transitions at 2 mm and the J = 18 → 17 and J = 21 → 20 transitions at 1.2 mm of this linear, closed-shell molecule were observed in this object. The line profiles appear U-shaped, indicating a source ≃20″, and the horn-to-center ratios suggest a shell-like distribution. In contrast, the other two Al-bearing molecules previously detected, A1F and A1C1, exist exclusively near the stellar photosphere. Modeling of the detected transitions, assuming a spherical-shell distribution, indicates a column density of Ntot ∼9 × 1011 cm-2 and a fractional abundance relative to H2 of ∼ 3 × 10-10 for A1NC. A rotational temperature of Trot ∼ 60 K was also derived for this molecule, suggesting that shock waves may be synthesizing A1NC in the outer envelope. This species is the fourth metal cyanide/isocyanide compound discovered in this object, along with MgNC, MgCN, and NaCN. These data suggest that cyanide/isocyanide species are the major molecular carriers of metals in circumstellar gas.
KW - Circumstellar matter
KW - ISM: molecules
KW - Line: identification
KW - Radio lines: stars
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U2 - 10.1086/338775
DO - 10.1086/338775
M3 - Article
AN - SCOPUS:0011159364
SN - 0004-637X
VL - 564
SP - L45-L48
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1 II
ER -