  We report possible interaction between multiple super nova remnants (SNRs)
and Northern Coal Sack (NCS) which is a massive clump (~1000 Mo) in the Cyg OB
7 cloud complex and is forming a massive Class 0 object. We performed molecular
observations of the 12CO(J=1-0), 13CO(J=1-0), and C18O(J=1-0) emission lines
using the 45m telescope at the Nobeyama Radio Observatory, and we found that
there are mainly four velocity components at Vlsr=-20, -6, -4, and 10 km/s. The
-6 and -4 km/s components correspond to the systemic velocities of NCS and the
Cygnus OB 7 complex, respectively, and the other velocity components originate
from distinct smaller clouds. Interestingly, there are apparent correlations
and anti-correlations among the spatial distributions of the four components,
suggesting that they are physically interacting with one another. On a larger
scale, we find that a group of small clouds belonging to the -20 and 10 km/s
components are located along two different arcs around some SNRs including HB
21 which has been suggested to be interacting with the Cyg OB 7 cloud complex,
and we also find that NCS is located right at the interface of the arcs. The
small clouds are likely to be the gas swept up by the stellar wind of the
massive stars which created the SNRs. We suggest that the small clouds alined
along the two arcs recently encountered NCS and the massive star formation in
NCS was triggered by the strong interaction with the small clouds.
