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Detection of AlNC
in IRC+10216
A new circumstellar molecule, aluminum isocyanide,
has been detected at millimeter wavelengths towards IRC+10216 using the
IRAM 30-meter telescope. The J = 11 --> 10, J = 12 -->11, J = 13
--> 12, and J = 18 --> 17 rotational transitions of this species
at 131, 143, 155, and 215 GHz were observed in the envelope of this
object with line intensities on the order of TA* ~ 5 mK. The
line profiles for all transitions were U-shaped, indicating that the
emission of this molecule is extended with respect to the 19" beam of
the 30-meter telescope at 2mm. Therefore, AlNC appears to exist in the
outer envelope of IRC+10216, where MgNC and MgCN are present. The
column density of AlNC was found to be Ntot ~ 1012
cm-2, corresponding to a fractional abundance,
relative to H2, of f ~10-9. Detection
of this molecule is further evidence that refractory elements
preferentially form cyanide and isocyanide species in interstellar gas.
Below, spectra of the rotational transitions observed.
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