NH3 molecules in carbon-rich AGB stars

The Herschel Heterodyne Instrument for the Far-Infrared obtained high-resolution spectroscopic observations of numerous Galactic and extragalactic sources, including 12 carbon-rich Galactic asymptotic giant branch (AGB) stars.The ground-state ortho-NH3 emission at 572.498 GHz was detected toward eight sources (CW Leo,V384 Per,CIT 6,II Lup,V1417 Aql,V1418 Aql,V Cyg,and LP And),while BM Gem, V Hya,Y CVn,and S Cep were not detected.

We used the SHELL function in GILDAS/CLASS to fit the NH3 molecular spectral line profiles of these sources, obtaining the line expansion velocity, the integrated intensity, and the main-beam brightness temperature. For sources where NH₃ was not detected, we estimated upper limits on the integrated intensity of the NH3 line.