Resumen

GOMEZ, José F. et al. A sensitive search for methanol line emission toward evolved stars. Rev. mex. astron. astrofis [online]. 2014, vol.50, n.1, pp.137-143. ISSN 0185-1101.

We present a sensitive search for methanol line emission in evolved stars at 1 cm, aiming to detect, for the first time, methanol masers in this type of objects. Our sample comprised post-AGB stars and young planetary nebulae (PNe), whose mass-loss processes and circumstellar structures resemble those of young stellar objects(YSOs), where methanol masers are detected. Class I masers were searched for in 73 objects, whereas Class II ones were searched in 16. No detection was obtained. The non-detection of Class I methanol masers indicated that methanol production in dust grains and/or the enhancement of its gas-phase abundance in the shocked regions of evolved objects are not as effcient as in YSOs. We suggest that relatively more evolved PNe might have a better probability of harboring Class II masers.

Palabras llave : ISM [molecules]; masers; stars [AGB and post-AGB].