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By G. R. Burbidge, F. D. Kahn, R. Ebert, S. v. Hoerner, St. Temesváry (auth.)

ISBN-10: 3662013282

ISBN-13: 9783662013281

ISBN-10: 3662013290

ISBN-13: 9783662013298

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Also, they have divided the outer envelope into two zones, the outer one in which the Kramers opacity alone is operating, and an inner one in which the electron scattering alone is at work. Since, ideally, contributions from both sources of opacity should be taken into account throughout the envelope, the result of this has been that they have slightly exaggerated the luminosities. Slight changes in luminosity can also be obtained if the assumed composition of the envelope (90% hydrogen and 10% helium) were changed.

In an isothermal contraction in which the dimension is decreased by a factor x, the gravitational energy released is of the order of GM2 (1- x)/R while the thermal energy generated by direct compression is of the order of 3 M9\ T loge x, and to maintain isothermal conditions this energy must be removed from the gas. In order that the gravitational energy is dissipated in this way these two quantities must be nearly equal, and this demands that the condensation must be only just unstable against contraction, and it must not contract too far.

32 Theoretical evolutionary tracks II. Theoretical evolutionary tracks 12. Gravitational contraction of protostars on to the main sequence So far we have described the various proposals which have been suggested for the formation of protostars. Once these have formed the stages of contraction and fragmentation will continue to take place, until the protostar becomes opaque and the adiabatic condition is fulfilled. Further contraction will then occur at a rate which is determined by the opacity of the stellar material, i.

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Die Entstehung von Sternen durch Kondensation diffuser Materie: 3 Preisschriften by G. R. Burbidge, F. D. Kahn, R. Ebert, S. v. Hoerner, St. Temesváry (auth.)


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