Chandrasekhar limit
The Chandrasekhar limit is the approximate upper mass at which a white dwarf can remain stable against its own gravity. For the usual idealized model, it is about 1.4 times the Sun’s mass. The limit follows from the way quantum-supported electron pressure changes as a stellar remnant becomes more massive and compact. It helps explain why some white dwarfs can undergo thermonuclear explosions, while sufficiently massive stellar remnants may collapse into denser objects.
What the limit describes
A white dwarf is the compact remnant left when a star has shed its outer layers. It no longer sustains the ordinary fusion reactions that powered the star. Instead, the remnant is supported against further gravitational compression largely by electron degeneracy pressure, a quantum-mechanical effect. The Chandrasekhar limit describes the approximate maximum mass of a stable white dwarf in the standard idealized model: about 1.4 times the mass of the Sun.
Why a maximum mass exists
As matter is compressed, electrons are forced into increasingly energetic states. Quantum physics and special relativity together determine how much pressure this electron gas can provide. Chandrasekhar showed that, beyond a critical mass, electron degeneracy pressure cannot maintain a stable white-dwarf configuration against gravity. The commonly quoted value is approximate; the exact theoretical mass depends on the assumptions used, including the remnant's composition and physical state. It is therefore a limit for white-dwarf stability, not a single universal mass threshold for every kind of star or stellar explosion.
Consequences for stellar evolution
A white dwarf in a binary system can gain material from a companion. As it approaches the critical range, conditions may trigger runaway nuclear burning and a thermonuclear explosion; NASA describes such events in accreting white dwarfs. Other sufficiently massive stellar cores can collapse into objects such as neutron stars or black holes. These outcomes depend on the star's composition, history and route to instability, so exceeding the white-dwarf mass limit should not be treated as a guarantee of one particular endpoint. The limit is central to models of stellar evolution and to interpreting supernovae, but it does not by itself settle every question about how a given explosion begins.
Chandrasekhar's work
Subrahmanyan Chandrasekhar formulated the result in 1930, applying relativity and quantum physics to the structure of white dwarfs. His work helped establish that a star's mass strongly constrains its final state. The limit bears his name, and his broader theoretical studies of the structure and evolution of stars contributed to the 1983 Nobel Prize in Physics, shared with William A. Fowler.
Key facts
- Meaning
- Approximate maximum mass of a stable white dwarf in the standard idealized model.
- Usual approximate value
- About 1.4 times the mass of the Sun; the precise theoretical value depends on model assumptions.
- Physical support
- Electron degeneracy pressure, a quantum-mechanical effect, counteracts gravity in a white dwarf.
- Origin
- Subrahmanyan Chandrasekhar formulated the limit in 1930 using relativity and quantum physics.
- Astrophysical relevance
- Approaching the limit can be important in accreting white dwarfs and thermonuclear explosions, but the mass limit alone does not determine every object's fate.
Timeline
1930
Subrahmanyan Chandrasekhar formulated the mass limit for stable white dwarfs.
1983
Chandrasekhar shared the Nobel Prize in Physics for theoretical studies of the structure and evolution of stars.
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References
- 1.Chandrasekhar limit
Encyclopaedia Britannica · other · reliability: high · retrieved 22 October 2026
Supports: Definition and approximate mass, the 1930 formulation, quantum and relativistic basis, and possible outcomes for stars above the limit.
- 2.The 1983 Nobel Prize in Physics - Speed read: Death of a star, Alchemy in the stars
Nobel Prize Outreach · other · reliability: high · retrieved 22 October 2026
Supports: Chandrasekhar's critical-mass calculation, its approximate 1.4-solar-mass value, implications for stellar collapse, and the 1983 prize context.
- 3.Pushing White Dwarfs Over the Edge
NASA Goddard Space Flight Center, High Energy Astrophysics Science Archive Research Center (HEASARC) · other · reliability: high · retrieved 22 October 2026
Supports: Electron degeneracy pressure supports white dwarfs up to about 1.4 solar masses; accretion in a binary can raise mass and lead to a thermonuclear explosion.
References are suggested by the research engine and may be incomplete. Unverified URLs are omitted rather than guessed.
Article history
- Version 122 October 2026 · EditorCreated by Zapia