Stars are often described as if they evolve alone, but many are born in binary systems and orbit a shared center of mass. A close companion can change a star’s evolution by transferring material to it. This lesson explains how mass transfer onto a white dwarf can produce a nova.
A binary star system consists of two stars bound by gravity and orbiting a common center of mass. If the stars are close enough, material can pass from one to the other. This often happens when one star expands into a giant or loses material through a strong stellar wind.
All flashcards
How does a nova differ from a type Ia supernova?
A nova ejects much of the newly accumulated surface material while the white dwarf survives; a type Ia supernova destroys the white dwarf.
What spectral features are associated with type Ia supernovae?
Their spectra lack hydrogen and show strong silicon absorption lines.
What is the double-degenerate pathway to a type Ia supernova?
Two white dwarfs spiral together and merge; if their combined mass exceeds the Chandrasekhar limit, the merger may produce a type Ia supernova.
How can accretion turn a neutron star into a millisecond pulsar?
Accreted material transfers angular momentum to the neutron star, increasing its rotation rate.
What can happen to a binary neutron-star system as it loses orbital energy?
The neutron stars can spiral toward one another and eventually merge, producing an event studied through gravitational waves.
Quiz questions
What happens to the white dwarf in a type Ia supernova?Answer: It is completely disrupted, leaving no white-dwarf remnant.
Which process describes the double-degenerate pathway to a type Ia supernova?Answer: Two white dwarfs merge after spiraling together, with their combined mass exceeding the Chandrasekhar limit.
Which spectral pattern is characteristic of a type Ia supernova?Answer: No hydrogen features and strong silicon absorption features.
Why are type Ia supernovae useful as standard candles?Answer: Their peak luminosities and light-curve patterns are relatively consistent.
How can accreted material increase a neutron star's rotation rate?Answer: It transfers angular momentum to the neutron star as it falls onto it.
Based on Astronomy 2e by Andrew Fraknoi, David Morrison, Sidney Wolff (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.