H I line observations of 290 evolved stars made with the Nançay Radio Telescope

We present a compendium of H I 21-cm line observations of circumstellar envelopes (CSEs) of 290 evolved stars, mostly (~84%) on the asymptotic giant branch (AGB), made with the 100 m-class, single-dish Nançay Radio Telescope. The observational and data reduction procedures were optimised to separate genuine CSE H I emission from surrounding Galactic line features. For most targets (254), the results have not been previously published. Clear detections were made of 34 objects, for 33 of which the total H I flux and the size of the CSE could be determined. Possible detections were made of 21 objects, and upper limits could be determined for 95 undetected targets, while for 140 objects confusion from Galactic H I emission along the line of sight precluded meaningful upper limits. The collective results of this survey can provide guidance on the detectability of circumstellar H I gas for future mapping and imaging studies.