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The Henyey track is a path taken by
The Henyey track is a path taken by pre-main-sequence star
A pre-main-sequence star (also known as a PMS star and PMS object) is a star in the stage when it has not yet reached the main sequence. Earlier in its life, the object is a protostar that grows by acquiring mass from its surrounding envelope of ...
s with masses greater than 0.5 solar mass
The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass ...
es in the Hertzsprung–Russell diagram
The Hertzsprung–Russell diagram, abbreviated as H–R diagram, HR diagram or HRD, is a scatter plot of stars showing the relationship between the stars' absolute magnitudes or luminosity, luminosities versus their stellar classifications or eff ...
after the end of the Hayashi track
The Hayashi track is a luminosity–temperature relationship obeyed by infant stars of less than in the pre-main-sequence phase (PMS phase) of stellar evolution. It is named after Japanese astrophysicist Chushiro Hayashi. On the Hertzsprung– ...
. The astronomer Louis G. Henyey
Louis George Henyey (February 3, 1910 – February 18, 1970) was an American astronomer.
His parents, Albert and Mary Henyey, were immigrants from Hungary. Louis George Henyey married Elizabeth Rose Belak, born in Budapest, on April 28, 1934; ...
and his colleagues in the 1950s showed that the pre-main-sequence star can remain in radiative equilibrium Radiative equilibrium is the condition where the total thermal radiation leaving an object is equal to the total thermal radiation entering it. It is one of the several requirements for thermodynamic equilibrium, but it can occur in the absence of t ...
throughout some period of its contraction to the main sequence.
The Henyey track is characterized by a slow collapse in near hydrostatic equilibrium
In fluid mechanics, hydrostatic equilibrium (hydrostatic balance, hydrostasy) is the condition of a fluid or plastic solid at rest, which occurs when external forces, such as gravity, are balanced by a pressure-gradient force. In the planetary ...
, approaching the main sequence almost horizontally in the Hertzsprung–Russell diagram (i.e. the luminosity
Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...
remains almost constant).
See also
* Historical brightest stars *List of brightest stars
This is a list of stars arranged by their apparent magnitude – their brightness as observed from Earth. It includes all stars brighter than magnitude +2.50 in visible light, measured using a ''V''-band filter in the UBV photometric system. Sta ...
* List of most luminous stars
This is a list of stars arranged by their absolute magnitude – their intrinsic stellar luminosity. This cannot be observed directly, so instead must be calculated from the apparent magnitude (the brightness as seen from Earth), the distance ...
* List of nearest bright stars
This list of nearest bright stars is a table of stars found within 15 parsecs (48.9 light-years) of the nearest star, the Sun, that have an absolute magnitude of +8.5 or brighter, which is approximately comparable to a listing of stars more lumi ...
* List of Solar System objects in hydrostatic equilibrium
This is a list of most likely gravitationally rounded objects of the Solar System, which are objects that have a rounded, ellipsoidal shape due to their own gravity (but are not necessarily in hydrostatic equilibrium). Apart from the Sun itself, ...
* Stellar evolution
Stellar evolution is the process by which a star changes over the course of time. Depending on the mass of the star, its lifetime can range from a few million years for the most massive to trillions of years for the least massive, which is cons ...
* Stellar birthline
The stellar birthline is a predicted line on the Hertzsprung–Russell diagram that relates the effective temperature and luminosity of pre-main-sequence stars at the start of their contraction. Prior to this point, the objects are accreting prot ...
* Stellar isochrone
In stellar evolution, an isochrone is a curve on the Hertzsprung-Russell diagram, representing a population of stars of the same age but with different mass.
The Hertzsprung-Russell diagram plots a star's luminosity against its temperature, or ...
References
* Stellar evolution Hertzsprung–Russell classifications {{Astronomy-stub