Math 2.0

Astronomy and astrophysics Definition

Henyey track

Builds on Hayashi trackStellar structureKelvin–Helmholtz mechanismEffective temperature

Definition

Fix a stellar mass MM and a chemical composition. Consider the pre-main-sequence evolutionary path of a star of mass MM in the plane of log⁡Teff\log T_{\mathrm{eff}} and log⁡L\log L. The Henyey track of mass MM is the part of this path during which:

  1. the star is in stellar structure equilibrium with a radiative core;
  2. the star contracts and is powered by the Kelvin–Helmholtz mechanism, before core hydrogen burning supplies its luminosity.

Here LL is the luminosity and TeffT_{\mathrm{eff}} the effective temperature.

Remarks

The track starts where the star leaves its Hayashi track and ends at the zero-age main sequence. For a radiative star of constant opacity, scaling arguments give a luminosity nearly independent of the radius, which is why LL changes little while TeffT_{\mathrm{eff}} rises. Example: a star of one solar mass leaves its Hayashi track when a radiative core appears. It then moves to the left along its Henyey track until it reaches the main sequence. Non-example: a star of 0.20.2 solar masses stays fully convective until it reaches the main sequence, so its path is a Hayashi track and has no Henyey part.

Reading path

To understand this page from the ground up, read these 5 pages in order. The foundations come first.

Show the path as a graph
Effective temperature, concept, no evidence levelEffective temperatureconceptHayashi track, concept, no evidence levelHayashi trackconceptKelvin–Helmholtz mechanism, concept, no evidence levelKelvin–Helmholtz mech…conceptStellar structure, concept, no evidence levelStellar structureconceptHenyey track, definition, no evidence levelHenyey trackdefinition
Each page uses the pages above it. The colour of the bar on a box shows how strong the evidence is, and the box also gives it as text. The list has the same pages.
  • no evidence level
  1. Effective temperature concept
  2. Hayashi track concept
  3. Kelvin–Helmholtz mechanism concept
  4. Stellar structure concept
  5. Henyey track definition

Further reading

  1. Web https://en.wikipedia.org/wiki/Henyey_track
About this page
TagX95A7HME0J
URIm2://X95A7HME0J
Kinddefinition
WritingW0 stub
MSC85A15
DefinesHenyey track
UsesHayashi track, Stellar structure, Kelvin–Helmholtz mechanism, Effective temperature
Changed3 November 2026

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