Astrophysics & Particle Physics-APPC 2026

Protostars are the first stage of stellar evolution that can be seen, which occurs when regions of high density in molecular clouds collapse due to gravity. Throughout this phase, the collapsing gas and dust pile up in a central core, with an accretion disk that delivers material onto the star forming around it. Protostars are usually surrounded by dust and therefore infrared and submillimeter observations are necessary to derive their properties.Protostars can be divided into evolutionary classes (0, I, II, III) depending on their spectral energy distribution and the envelope mass surrounding them. Class 0 are the youngest and most deeply embedded protostars, Class I and II objects with decreasing envelope mass and growing visibility.

T Tauri stars and Herbig Ae/Be stars are later pre-main sequence phases that evolve toward main-sequence stars.Current telescopes such as ALMA (Atacama Large Millimeter/submillimeter Array) and the James Webb Space Telescope (JWST) enable astronomers to image protostellar envelopes, disks, and jets at high resolution, which exposes the physical and chemical conditions that create the environment for the formation of planets.Summarily, protostars are stellar building blocks that symbolize the birth stage in stellar evolution. Observing them helps us better understand star birth, disk evolution, and the origin of planetary systems in our own galaxy and others.