The rotational spectra of 29SiC2 and 30SiC2

The rotational spectra of ²⁹SiC2 and ³⁰SiC2, two silicon isotopic species of the abundant astronomical ring ²⁸SiC2, have been characterized in the millimeter band between 140 and 360GHz in a low pressure discharge through SiH4, C2H2, and Ar. Precise rotational and centrifugal distortion constants have been derived for both species by fitting a standard asymmetric top Hamiltonian to 38 a-type transitions of ²⁹SiC2 and 35 of ³⁰SiC2; the data sets include transitions up to Ka = 8 and at least J = 16. With these new measurements in hand, the most intense radio transitions of both species either have been measured or can now be predicted to better than 1kms ^-1 in equivalent radial velocity up to 500GHz, more than adequate accuracy for spectral line identifications in circumstellar shells of evolved carbon stars such as IRC+10216 where SiC2 is conspicuous. More than 10 new lines of ²⁹SiC2 and ³⁰SiC2 have been identified between 295 and 354GHz in the interferometric spectral line survey of IRC+10216 with the Submillimeter Array. © 2011. The American Astronomical Society. All rights reserved.

Duke Scholars

Author Ken H Young Pathology