Structures in the interstellar medium

HI shells and supershells belong to the most striking structures in the distribution of the interstellar medium in galaxies. Majority of them are created by the energetic activities of massive stars, mostly by supernovae explosions combined the intense radiation and stellar winds, but there are structures of unknown origins, where the stellar origin is not believable. The role of HI shells is not straighforward: walls of these structures expand into the neighbouring interstellar medium destroying existing molecular clouds and therefore decreasing the star formation in their vicinity, but also sweeping the surrounding material into dense sheets, promoting creation of new clumps and clouds and thus increasing the star formation.

Alt description


    - Supershell, shells, IR bubbles in MW and other galaxies
      (including the Carina Flare supershell)
    - Dependence of clump mass function on galactic z? (CF and other shell; Planck cold clumps)
    - Shell in the Galactic centre
    - Formation of molecular clouds, impact of feedback, SF law in galaxies, SILCC
    - Identifying and analysing shells in SILCC runs
    - radio observations of gas (APEX, archive HI, CO, dust observations)
    - IR observations of gas and dust (Spitzer, Herschel archives)
    - optical observations of HII regions (MP2.2, VLT)
    - shell identification code - HOLMES
    - Hydrodynamic simulations + physics of ISM; synthetic observations
    - thin-shell/n-body code ring
    - Observation of stars???
    - Genetic algorithms - to find shell parameters???
    - Deep learning to identify shells / other structures?
   Scientific questions:
    - Do shells help to form molecular clouds? (Depending of galaxy type)
    - Do shells trigger star formation?
    - What is the role of feedback (and which type)?
    - What can shells tell us about past feedback of young stars?
    - What is the origin of stellar IMF and mass function of clusters?