Hayashi forbidden zone zonâr-e baſkam-e Hayashi Fr.: zone interdite de Hayashi The region to the right the → Hayashi track, representing objects that cannot be in → hydrostatic equilibrium. Energy transport in these objects would take place with a → superadiabatic temperature gradient. → Hayashi track; → forbidden; → zone. |
Hayashi phase fâz-e Hayashi Fr.: phase de Hayashi A period in the → pre-main sequence evolution of a low mass star during which the star has negligible nuclear energy production and low internal temperature. Hence energy transport inside the star takes place dominantly through → convection. The star contracts homologously and evolves in the → H-R diagram along the → hayashi track with decreasing → luminosity and nearly constant → effective temperature. The time taken by a star of mass M* to contract to radius R* along a Hayashi track is of the order of the → Kelvin-Helmholtz time: tKH = 107(M*/Msun)2/(R*/Rsun)3 yr. → Hayashi track; → phase. |
Hayashi temperature damâ-ye Hayashi Fr.: température de Hayashi The minimum → effective temperature required for a → pre-main sequence star of given mass and radius to be in → hydrostatic equilibrium. This temperature delimits the boundary of the → Hayashi forbidden zone. → Hayashi track; → temperature. |
Hayashi track tor-e Hayashi Fr.: trajet de Hayashi The path on the → Hertzsprung-Russell diagram that is followed by a fully → convective → pre-main sequence star to reach the → zero-age main sequence. Hayashi tracks for → low-mass stars are near vertical. At higher masses, stars become increasingly radiative as they contract and the Hayashi tracks are almost horizontal. Named after the Japanese astrophysicist Chushiro Hayashi (1920-2010), who published his paper in 1961 (PASJ 13, 450); → track. |