Observational evidence for supernova-induced star formation - Canis Major R1

Abstract

Observational evidence is presented which indicates that star formation in the young association CMa R1 was initiated by a supernova explosion (probably of Type II) that occurred about half a million years ago. Palomar Sky Survey prints, neutral-hydrogen maps, and radial-velocity data are examined which show that the CMa R1 association is located on the outer edge of a ring of optical and radio emission, that an expanding neutral-hydrogen shell is coincident with the optical feature, and that HD 54662 is a runaway star in the CMa OB1 association and may be associated with the event that produced the observed supernova remnant. The optical and radio features are interpreted as a supernova remnant with an age of about 500,000 years and an initial outburst energy of the order of 5 by 10 to the 50th power ergs, which is expanding into an initially nonuniform medium characterized by an initial atomic-hydrogen density of approximately 1 per cu cm in the direction toward CMa R1 and less than half that value in the direction toward the sun.