Nobeyama 45 m Local Spur CO survey. I. Giant molecular filaments and cluster formation in the Vulpecula OB association

We have performed new large-scale (CO)-C-12, (CO)-C-13, and (CO)-O-18 J = 1-0 observations toward the Vulpecula OB association (I similar to 60 degrees) as part of the Nobeyama 45 m Local Spur CO survey project. Molecular clouds are distributed over similar to 100 pc, with local peaks at the Sh 2-86, Sh 2-87, and Sh 2-88 high-mass star-forming regions in the Vulpecula complex. The molecular gas is associated with the Local Spur, which corresponds to the nearest inter-arm region located between the Local Arm and the Sagittarius Arm. We discovered new giant molecular filaments (GMFs) in Sh 2-86, with a length of similar to 30 pc, width of similar to 5 pc, and molecular mass of similar to 4 x 10(4) M-circle dot. We also found that Sh 2-86 contains the three velocity components at 22,27, and 33 km s(-1). These clouds and GMFs are likely to be physically associated with Sh 2-86 because they have high (CO)-C-12 J = 2-1 to J = 1-0 intensity ratios and coincide with the infrared dust emission. The open cluster NGC 6823 exists at the common intersection of these clouds. We argue that the multiple cloud interaction scenario, including GMFs, can explain cluster formation in the Vulpecula OB association.

Automated summary

In this study, new giant molecular filaments (GMFs) were discovered in the Vulpecula OB association, which are likely to be associated with the Sh 2-86 star cluster. Further investigations revealed that these GMFs coincide with the infrared dust emission. The scenario of multiple cloud interaction may explain cluster formation in the Vulpecula OB association.