Exploring GLIMPSE bubble N107

Abstract

Context. Bubble N107 was discovered in the infrared emission of dust in the plane of the Milk y Way Galaxy observed by the Spitzer Space Telescope (GLIMPSE survey: l ≈ 51.̊0, b ≈ 0.̊1). The bubble represents an example of shell-like structures found all over the Milky Way Galaxy. Aims: We aim to analyse the atomic and molecular components of N107, as well as its radio continuum emission. With the help of numerical simulations, we aim to estimate the bubble's age and other parameters that cannot be derived directly from observations. Methods: From the observations of the H i (I-GALFA) and 13CO (GRS) lines we derive the bubble's kinematical distance and masses of the atomic and molecular components. With the algorithm DENDROFIND, we decompose molecular material into individual clumps. From the continuum observations at 1420 MHz (VGPS) and 327 MHz (WSRT), we derive the radio flux density and the spectral index. With the numerical code ring, we simulate the evolution of stellar-blown bubbles similar to N107. Results: The total H i mass associated with N107 is 5.4 × 103 M⊙. The total mass of the molecular component (a mixture of cold gasses of H2, CO, He, and heavier elements) is 1.3 × 105 M⊙, from which 4.0 × 104 M⊙ is found along the bubble border. We identified 49 molecular clumps distributed along the bubble's border, with the slope of the clump mass function of -1.1. The spectral index of -0.30 of a strong radio source located apparently within the bubble indicates nonthermal emission, hence part of the flux probably originates in a supernova remnant, not yet catalogued. The numerical simulations suggest N107 is most likely less than 2.25 Myr old. Since the first supernovae explode only after 3 Myr or later, no supernova remnant should be present within the bubble. It may be explained if there is a supernova remnant in the direction towards the bubble, however not associated with it.