Kinematics of the bright rimmed globules in IC1396

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Session 99 -- Molecular Clouds and Star Formation
Oral presentation, Friday, January 14, 2:15-3:45, Salon VI Room (Crystal Gateway)

[99.03] Kinematics of the bright rimmed globules in IC1396

N.A.Patel (FCRAO,UMass), P.F.Goldsmith (NAIC), R.Snell,T.Hezel (FCRAO,UMass), T.Xie (JPL), J.Carpenter (FCRAO,UMass)

We have mapped a $3^{o} \times 3^{o}$ region around the diffuse HII region IC1396 in CO and $^{13}$CO J=1-0 to study the structure, kinematics and evolution of the bright rimmed globules in this region. The observations were made using the FCRAO 14m telescope with the QUARRY receiver. The observed velocities of these globules and their locations on the plane of the sky are consistent with a model in which the globules lie on an expanding ring around the central exciting star. The globules appear to be moving away from the O6 star HD206267 with a velocity of about 6 $km\; s^{-1}$. The diameter of this ring of globules is about 20pc. This ring itself seems to be embedded in a large scale shell in the Cepheus region (diameter $\sim 100$ pc) which was discovered in IRAS $100\mu m$ emission by Kun et al.\ (1987, Ap \& SS,134,211). A comparison of the mass of the molecular gas with that of the atomic and ionized gas suggests that most of the gas in this region is very effectively dissociated by the UV radiation from HD206267. Based on the association of color selected IRAS point sources, it appears that many of these globules are currently forming stars, presumably as a consequence of radiative implosion. We have observed CS J=2-1 in selected globules to compare the density structure of the globules which appear to be forming stars, with those which are relatively quiescent. The results of the large scale CO mapping, pertinent to the overall evolution of this HII region/molecular cloud complex, and the results of the $^{13}$CO and CS observations which can be used to determine the physical properties of the bright rimmed globules, will be discussed in the context of current models.

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