By Y. Ryabov, G. Yankovsky
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Additional resources for An Elementary Survey of Celestial Mechanics
Chemical composition: XH D 0:708, X3 He D 0:0, X4 He D 0:272, X12 C D 0:00361, X14 N D 0:00120, X16 O D 0:00108. The mixing length is determined by the density scale height: l D =2jr j (see Sect. 1, Vol. 1) viscosity leading to an unphysical angular momentum inflow to the centre which results in torus formation. The results of Lagrangian calculations seem more reliable. We present here the results obtained in [35, 42]. 32) 16 7 Star Formation Fig. 6 and 6Mˇ . Each track is labeled by the corresponding mass in solar units.
The evolutionary tracks of stars calculated in  from the Hayashi boundary are shown in Fig. 1. The chemical composition corresponds to xH D 0:7, xHe D 0:27, xZ D 0:03. The atmosphere and envelope are calculated similarly to  by solving equations for the static atmosphere with an approximate description of optically thin layers with < 1. This description gives a smooth transition to the equation for the radiative heat conductivity, valid for deep layers inside the photosphere (see Sects.
The applied method was analogous to that in  which included radiative transfer in moving matter to the Eddington approximation (see Sect. 5, Vol. 1), and deuterium burning as well. The opacity tables from [19, 316, 419] were used. The initial and boundary conditions were similar to those in . The optical star appears with R D 4:69Rˇ , L D 6:20Lˇ . These calculations underlie the birthline for low-mass stars with 0:2Mˇ Ä M Ä 1Mˇ obtained in , where stars appear in the optical range and continue to evolve towards the main sequence along the Hayashi track (Fig.
An Elementary Survey of Celestial Mechanics by Y. Ryabov, G. Yankovsky