The Interstellar Environment of Filled-Center Supernova Remnants III: The Crab Nebula

The HI environment of the Crab Nebula is investigated using 2.75' and 9' resolution data from (respectively) the DRAO Synthesis, and Effelsberg 100 m, radio telescopes. No clear evidence for an interaction between the Crab and the surrounding HI is found; the Crab probably lies within the boundaries of a large scale, low-density void in the HI distribution. The presence of a wind-blown HI bubble near the Crab is confirmed, and it is suggested that the unidentified star which powers this bubble is responsible for the stellar wind material detected along the line of sight towards the Crab.