The interstellar environment of filled-center supernova remnants. III. TheCrab Nebula

The H I environment of the Crab Nebula is investigated using 2.'75 and 9' r esolution data from the Dominion Radio Astrophysical Observatory Synthesis and Effelsberg 100 m Radio Telescopes, respectively. No clear evidence for an interaction between the Crab and the surrounding H I is found; the Crab probably lies within the boundaries of a large-scale, low-density void in t he H I distribution. The presence of a wind-blown H I bubble near the Crab is confirmed, and it is suggested that the unidentified star that powers th is bubble is responsible for the stellar wind material detected along the l ine of sight toward the Crab.