Multi-epoch high-resolution spectroscopy of SN 2011fe: Linking the progenitor to its environment

Aims. The nearby Type Ia supernova (SN) 2011 fe has provided an unprecedented opportunity for deriving some of the properties of its progenitor. This work provides additional and independent information on the circumstellar environment in which the explosion took place. Methods. We obtained high-resolution spectroscopy of SN 2011fe for 12 epochs, from 8 to 86 days after the estimated date of explosion, testing in particular the time evolution of CaII and NaI. Results. Three main absorption systems are identified from CaII and NaI, one associated to the Milky Way, one probably arising within a high-velocity cloud, and one most likely associated to the halo of M101. The total (Galactic and host galaxy) reddening, deduced from the integrated equivalent widths (EW) of the NaI lines, is E sub(B-V) [