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Astron. Astrophys. 354, 645-656 (2000)

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5. Summary

We investigated the spatial and velocity distribution of atomic hydrogen associated with the Cepheus Bubble, a giant dust ring around the older part of the Cep OB2 association. Using HI 21 cm data, taken from the Leiden/Dwingeloo survey, as well as IRAS and optical data, we have reached the following results:

  1. We identified the main HI structures associated with the dust ring in the velocity range [FORMULA] kms-1.

  2. At least three quarters of the ring seem to be located at 900 pc, and we suggest the existence of a physically contiguous, almost complete ring around the older subgroup of the Cep OB2 association.

  3. The HI data reveal an expanding shell with a radial velocity difference of [FORMULA] kms-1 between the approaching and receding sides. In order to compare its kinematics with the analytical theoretical results of expanding shells we introduced an `effective expansion velocity' of [FORMULA] kms-1 taking into account the 1:4 density ratio between the approaching and receding sides. The size and kinematics of this shell can best be modelled by a SN explosion occuring at about 1.7 Myrs ago.

  4. The time scale of the SNR expansion is considerably lower than the age of several parts of the Cepheus Bubble, suggesting that the supernova was probably exploded in an already existing cavity. The expanding shock front then interacted with the already existing star forming regions Sh2-140, IC 1396, and NGC 7129 at the inner edge of the Bubble, leading to a new wave of star formation there.

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© European Southern Observatory (ESO) 2000

Online publication: February 9, 2000