Molecular Environment of the Supernova Remnant IC 443: Discovery of the Molecular Shells Surrounding the Remnant

摘要

We have carried out 12CO, 13CO, and C18O observations toward the mixedmorphology supernova remnant (SNR) IC 443. The observations cover a 1.5*1.5deg^2 area and allow us to investigate the overall molecular environment of theremnant. Some northern and northeastern partial shell structure of CO gas isaround the remnant. One of the partial shells, about 5' extending beyond thenortheastern border of the remnant's bright radio shell, seems to just confinethe faint radio halo. On the other hand, some faint CO clumps can be discernedalong the eastern boundary of the faint remnant's radio halo. Connecting theeastern CO clumps, the northeastern partial shell structures, and the northernCO partial shell, we can see that a half molecular ring structure appears tosurround the remnant. The LSR velocity of the half-ring structure is in therange of -5 km/s to -2 km/s, which is consistent with that of the -4 km/smolecular clouds. We suggest that the half-ring structure of the CO emission atV_LSR -4 km/s is associated with the SNR. The structures are possibly swept upby the stellar winds of SNR IC 443's massive progenitor. Based on theWide-field Infrared Survey Explorer and the Two Micron All Sky Survey near-IRdatabase, 62 young stellar object (YSO) candidates are selected within theradio halo of the remnant. These YSO candidates concentrated along the boundaryof the remnant's bright radio shell are likely to be triggered by the stellarwinds from the massive progenitor of SNR IC 443.