akkrettere

Akkrettere is a term used mainly in Norwegian-language astronomy to denote accreting compact objects—white dwarfs, neutron stars, and black holes—that gain mass by drawing material from a companion star in a binary system. The term is the Norwegian form of the English word accretor and is tied to the broader process of accretion, where gravitational energy released by infalling matter powers the object’s emission.

Mass transfer typically occurs through Roche lobe overflow, where the donor star fills its critical gravitational equipotential surface and transfers matter through the inner Lagrangian point, or by capturing the donor's stellar wind. The transferred gas generally forms an accretion disk around the compact object due to angular momentum, heating up and emitting across the electromagnetic spectrum, with X-ray emission common in many systems.

Observationally, akkrettere are identified as X-ray binaries when the compact object emits strongly in X-rays, or as accreting white dwarfs in cataclysmic variables, which can undergo nova-like outbursts. The accretion rate and the nature of the accretor influence phenomena such as thermonuclear bursts on neutron stars, classical novae on white dwarfs, and, in some cases, relativistic jets.

In the broader literature, the English term accretor is more common, but akkrettere appears in Norwegian astronomy texts. Studying akkrettere informs binary evolution, end-of-life stellar processes, and high-energy astrophysics.