| Abstract: | The Milky Way is a spiral galaxy composed of billions of stars, gas, and dust. Within this cosmic expanse, molecular clouds, dense regions of gas and dust, play a crucial role in the formation of new stars. These clouds, often grouped into massive complexes, exert a significant gravitational influence on the surrounding interstellar medium. A fascinating phenomenon, known as the "pinching effect," occurs when these molecular cloud complexes compress the surrounding atomic hydrogen (H I) gas, reducing its vertical scale height. This gravitational force effectively flattens the gas layer, making it thinner and more concentrated. Recent observational studies have provided compelling evidence for this pinching effect. By analyzing multi-wavelength observations of the Milky Way, we have identified molecular cloud complex that exhibit a clear impact on the surrounding H I gas. These observations reveal a distinct reduction in the vertical extent of the H I layer in the vicinity of the complex. The pinching effect has profound implications for our understanding of galactic structure and evolution. By altering the distribution of gas, these molecular cloud complexes can influence star formation rates and the overall dynamics of the galactic disk. Furthermore, the study of this phenomenon can provide valuable insights into the interplay between gravity, gas, and stars in galaxies. |
