It is difficult to distinguish between these scenarios (see, e.g. In the second scenario, the shock front compresses existing cold clumps and thus initiates the star formation. In the first one, the interstellar medium is swept up into a dense, cold layer and this layer gravitationally fragments and then forms stars. There are two basic mechanisms proposed to explain such triggering: collect & collapse (C&C) and radiation driven implosion (RDI). (2010), suggesting triggered star formation. The walls delineating the IR bubbles are associated with sites of new star formation, that is, they contain objects younger than the predicted age of the bubble itself – many examples can be found in Deharveng et al. Basically all infrared (IR) bubbles are found near ionized hydrogen (HII) regions, CO clouds, or other indicators of recent or on-going star formation. Progenitors of these bubbles, which are most easily observed in the infrared band, include stellar winds, intense radiation of massive stars, or supernova explosions. 2012), which describes the state of the ISM. Their (nearly) ubiquitous presence is the reason behind the term “the bubbling galactic disk” ( Churchwell et al. Some of the structures resemble envelopes and are known as shells or bubbles. The interstellar medium (ISM) in the Galaxy shows a rich variety of structures, including clumps, filaments and dense sheets. Key words: ISM: bubbles / ISM: clouds / HII regions / ISM: supernova remnants Interstellar material, suggesting that they are an important mechanism for star We propose that suchĬollisions increase the probability of further star formation, probably by squeezing the We found that both infrared bubbles N115 and N116+117 areĪssociated with the collisions of larger and older bubbles. Than a million years) infrared bubble lies at the position of the collision.Ĭonclusions. They are both formed by two largeĬolliding bubbles with radii around 20–30 pc and ages of a few million years. Lying at different distances, but look similar. Two large HI bubbles, which we discovered in the HI data. The second, the foreground system, includes the infrared bubble N115 and System, is formed by large structures G053.9+0.2 and SNR G054.4-0.3 and the infraredīubble N116+117. We identified two systems of bubbles: the first, the background Size, expansion velocity, mass, original density of the maternal cloud, age, and energy The IR images and applied them to the HI and CO data. We manually constructed masks based on the appearance of the bubbles in To find bubbles in HI (Very Large Array Galactic Plane Survey)Īnd CO data (Galactic Ring Survey), we used the images from the Galactic Legacy Infrared Properties of the bubbles, we also look into their ambient environment to understand their With atomic, molecular and ionized gas in this region. We compare infrared observations of bubbles N115, N116 and N117 Objects are commonly associated with these structures.Īims. Radiation of massive stars, or supernova explosions. Their progenitors are stellar winds, intense With diameters of a few to tens of parsecs. Interstellar bubbles are structures in the interstellar medium Republic, Boční II 1401, 141 31 Prague 4, Czech RepublicĬontext. Astronomical objects: linking to databasesĪstrophysicsFaculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech RepublicĮ-mail: Astronomical Institute, Academy of Sciences of the Czech.Including author names using non-Roman alphabets.Suggested resources for more tips on language editing in the sciences Punctuation and style concerns regarding equations, figures, tables, and footnotes
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