AN OVERVIEW OF THE INTERSTELLAR MEDIUM AND ITS ROLE IN STAR FORMATION

The interstellar medium (ISM) is made up mostly of gas and dust, threaded by magnetic fields and exposed to radiation and cosmic rays, and it provides the physical setting in which stars form. In its coldest, densest regions, molecular clouds contract under their own gravity. The collapsing material first organizes into filaments, and these filaments fragment into dense clumps, each of which may go on to form a star. Protostars emerge from these fragments surrounded by rotating accretion disks. How much of the structure of these regions, and of the pace of star formation, should be attributed to turbulence, to magnetic fields, or to feedback from nearby stars is still uncertain; different studies weight the three processes very differently, and no single mechanism seems likely to dominate everywhere. Many basic questions about star formation therefore remain open after decades of work. What has changed in recent years is how well the process can be observed. The James Webb Space Telescope (JWST) and the Atacama Large Millimeter/ submillimeter Array (ALMA) have pushed observational detail far beyond what was possible a decade ago and opened wavelength ranges that were previously inaccessible. Indian astronomers have also contributed substantially to this progress, particularly in interstellar chemistry, magnetic fields, and molecular cloud structure.