What is common envelope evolution?

Common-envelope evolution (CEE) is the name given to a short-lived phase in the life of a binary star during which two stars orbit inside a single, shared envelope. CEE is believed to be a vital process in the evolution of a large number and wide diversity of binary stars.

What is a stars envelope?

A circumstellar envelope (CSE) is a part of a star that has a roughly spherical shape and is not gravitationally bound to the star core. Usually circumstellar envelopes are formed from the dense stellar wind, or they are present before the formation of the star.

What do binary star mean?

Binary stars are two stars orbiting a common center of mass. The brighter star is officially classified as the primary star, while the dimmer of the two is the secondary (classified as A and B respectively). In cases where the stars are of equal brightness, the designation given by the discoverer is respected.

What do we call a binary system in which one star overflows its roche lobe?

Semidetached binary stars are binary stars where one of the components fills the binary star’s Roche lobe and the other does not. Gas from the surface of the Roche-lobe-filling component (donor) is transferred to the other, accreting star. The mass transfer dominates the evolution of the system.

When does a common envelope form in a binary star system?

A common envelope is formed in a binary star system when the orbital separation decreases rapidly or one of the stars expands rapidly.

What do you mean by common envelope in astronomy?

In astronomy, a common envelope (CE) is gas that contains a binary star system. The gas does not rotate at the same rate as the embedded binary system. A system with such a configuration is said to be in a common envelope phase or undergoing common envelope evolution.

What are the stages of a common envelope?

Key stages in a common envelope phase. Top: A star fills its Roche lobe. Middle: The companion is engulfed; the core and companion spiral towards one another inside a common envelope. Bottom: The envelope is ejected or the two stars merge. In astronomy, a common envelope ( CE) is gas that contains a binary star system.

How is a common envelope different from a contact binary?

A common envelope is sometimes confused with a contact binary. In a common envelope binary system the envelope does not generally rotate at the same rate as the embedded binary system; thus it is not constrained by the equipotential surface passing through the L2 Lagrangian point.