A sensitive line search in circumstellar envelopes

Abstract

A molecular line search in the range between 85 and 89 GHz has been performed in the circumstellar envelopes of 11 evolved stars. Emissions of ²⁹SiO J=2-1,²⁸SiO J=2-1, HCN J=1-0, H¹³CN J=1-0, HC₅ N J=33-32, HCO⁺ J=1-0 transitions and other transitions of C₂ H, C₄ H, and C₃ N have been observed in 11 stars. We have detected the ground state ²⁹SiO J=2-1 maser in several stars. We have also detected HCN emission in VY CMa. A narrow H¹³CN spike feature near the central velocity has been found in the spectrum of CRL 2688.