Protostellarfaserne

Protostellarfaserne is a term used to describe the sequence of early developmental stages through which a protostar evolves as it forms from a collapsing molecular cloud core and approaches the main sequence. The concept centers on the accumulation of mass, the presence of circumstellar material, and the changing observational properties that accompany these processes.

In the conventional view of protostellar evolution, the protostellar development is commonly divided into classes that reflect the relative dominance of envelopes and disks. Class 0 objects are deeply embedded, with most of the mass still in the envelope and strong submillimeter emission. Class I sources retain substantial envelopes but show rising infrared output due to the growing central object and disk. Class II objects are dominated by circumstellar disks with weaker envelopes, corresponding to classical T Tauri stages. Class III stages mark a waning disk and a star approaching the main sequence. The transitions between these phases are governed by mass accretion rates, envelope dispersal, disk evolution, and feedback processes such as bipolar outflows and jets.

Observationally, protostellarfaserne is studied through infrared to submillimeter wavelengths, where dust-enshrouded protostars emit and disks radiate. Key diagnostics include spectral energy distributions, bolometric temperature, and molecular-line tracers of envelopes and outflows. Facilities such as infrared space telescopes and ground-based submillimeter arrays provide data that help distinguish evolutionary stages.

The term protostellarfaserne is not standard in all astronomical literature; more common terms are protostellar evolution or protostellar classes. The concept remains central to understanding how stars form, accumulate mass, and initiate planet formation in surrounding disks.