Star Formation Associated With the SNR IC443

Abstract: We have performed the submillimeter and millimeter observations in CO lines toward supernova remnant (SNR) IC443. CO molecular shell is well coincident with the partial shell of the SNR detected in radio continuum observations. The broad emission lines and three 1720-MHz OH masers were detected in CO molecular shell. The present observations have provided further evidence in support of the interaction between the SNR and the adjoining molecular clouds (MCs). The total mass of the MCs is 9.26*10^{3} sun masses. The integrated CO line intensity ratio I(CO(3-2))/I(CO(2-1)) for the whole molecular cloud is between 0.79 and 3.40. The average value is 1.58, which is much higher than previous measurements of individual Galactic MCs. Higher line ratios imply that shocks have driven into the MCs. We conclude that high I(CO(3-2))/I(CO(2-1)) is identified as one good signature of SNR-MCs interacting system. Based on $IRAS$ Point Source Catalog and 2MASS near-infrared database, 12 protostellar objects and 1666 young stellar objects (YSOs) candidates (including 154 CTTSs and 419 HAeBe stars) are selected. In the interacting regions, the significant enhancement of the number of protostellar objects and YSOs indicates the presence of some recently formed stars. After comparing the characteristic timescales of star formation with the age of IC443, we conclude that the protostellar objects and YSOs candidates are not triggered by IC443. For the age of stellar winds shell, we have performed calculation on the basis of stellar winds shell expansion model. The results and analysis suggest that the formation of these stars may be triggered by the stellar winds of IC443 progenitor.