CO observation of the Galactic bubble N4

Abstract

We presented a study on the Galactic bubble N4 using the 13.7 m millimeter telescope of Purple Mountain Observatory at the Qinghai Station. N4 is one of the science demonstration regions for the Milky Way Imaging Scroll Painting (WMISP). Simultaneous observations of ${}^{12}$CO (J = 1$-$0), ${}^{13}$CO (J = 1$-$0) and C${}^{18}$O (J = 1$-$0) line emission towards N4 were carried out. We analyzed the spectral profile and the distribution of the molecular gas. Morphologically, the CO emissions correlate well with Spitzer IRAC 8.0 $\mu$m emission. The channel map and velocity-position diagram shows that N4 is more likely an inclined expanding ring than a spherical bubble. We calculated the physical parameters of N4 including the mass, size, column density and optical depth. Some massive star candidates were discovered in the region of N4 using (J, J$-$H) color-magnitude diagram. We found an energy source candidate for the expansion of N4, a massive star with a mass of $\sim 15M_{\odot }$ and an age of $\sim$ 1 Myr. There exists infall motion signature in N4, which can be a good candidate of infall area. Combined mm and infrared data, we think there may exists triggered star formation in N4.

13 pages; 10 figures; RAA in press

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• IR Dust Bubbles: Probing the Detailed Structure and Young Massive Stellar Populations of Galactic HII Regions
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Cited by in corpus (8)

• The Milky Way Imaging Scroll Painting (MWISP): Project Details and Initial Results from the Galactic Longitude of 25.8deg to 49.7deg
• Molecular gas in a Spitzer bubble N4: possible evidence for cloud-cloud collisions as a trigger of massive star formation
• A statistical study of gaseous environment of Spitzer interstellar bubbles
• A Curved Magnetic field in the ring-like shell of bubble N4
• Molecular Lines of 13 Galactic Infrared Bubble Regions
• FacetClumps: A Facet-based Molecular Clump Detection Algorithm
• Coeval intermediate-mass star formation in N4W
• Exponential galaxy discs as the quasi-stationary distribution in a Markov chain model simulating stellar scattering