Zero-age main-sequence radii and luminosities as analytic functions of mass and metallicity
Zero-age main-sequence radii and luminosities as analytic functions of mass and metallicity
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DOI：
10.1093/mnras/281.1.257
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发表时间：
1996-07
影响因子：
4.8
通讯作者：
C. Tout;O. Pols;P. Eggleton;Zhanwen Han
中科院分区：
文献类型：
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作者：
C. Tout;O. Pols;P. Eggleton;Zhanwen Han
我们给出了恒星的零龄主序半径和光度随质量和金属度的函数的拟合公式。这些公式涵盖了质量从0.1Mo到100Mo，金属度从Z=0.0001到0.03.在这个范围内，函数处处都是严格解析的。它们采用质量有理函数的形式，只有正系数以金属丰度多项式的形式计算。光度的误差一般不到7.5%，半径的误差一般不到5%。对于Z=0.02的太阳金属丰度，光度误差不到3%，半径误差不到1.2%。我们通过一种主要通过反复试验开发的设备来模仿这一点。从0.1Mo‘处的绝对零年龄混合物开始，我们通过增加质量使主序列随时间向上“演化”。在每个时间步长，模型的质量增加Tom‘=5~1000m，其中M是当前质量，因此第600个模型的质量为100Mo’。时间步长选择为Ilt=5‘KH/(M/Mo)，其中’KH是开尔文-亥姆霍兹时间尺度。本文给出了恒星的零龄主序半径和光度随质量和金属丰度的函数的拟合公式。这些公式涵盖了质量从0.1Mo到100Mo，金属度从Z=0.0001到0.03.在这个范围内，函数处处都是严格解析的。它们采用质量有理函数的形式，只有正系数以金属丰度多项式的形式计算。光度的误差一般不到7.5%，半径的误差一般不到5%。对于Z=0.02的太阳金属丰度，光度误差不到3%，半径误差不到1.2%。
We present fitting formulae for the zero-age main-sequence radii and luminosities of stars as functions of their masses and metallicities. The formulae cover masses from 0.1 to 100 Mo and metallicities from Z = 0.0001 to 0.03. Within this range the functions are everywhere strictly analytic. They take the form of rational functions in mass with only positive coefficients calculated as polynomials in metallicity. Errors are generally less than 7.5 per cent for luminosity and less than 5 per cent for radius. For a solar metallicity of Z = 0.02 these errors are less than 3 per cent for luminosity and 1.2 per cent for radius. We mimic this by a device which we developed mainly by trial and error. Starting with the absolute zero-age mixture at 0.1 Mo' we 'evolve' up the main sequence with time by adding mass. At each time-step the mass of the model is increased toM' =5~1000M, where M is the current mass, so that the 600th model has mass 100 Mo' The time-step is chosen to be Ilt = 5'KH/(M/M o ), where 'KH is the Kelvin-Helmholtz time-scale. The heat term - TDS/Dt (where T is the temperature and S the entropy) ABSTRACT We present fitting formulae for the zero-age main-sequence radii and luminosities of stars as functions of their masses and metallicities. The formulae cover masses from 0.1 to 100 Mo and metallicities from Z = 0.0001 to 0.03. Within this range the functions are everywhere strictly analytic. They take the form of rational functions in mass with only positive coefficients calculated as polynomials in metallicity. Errors are generally less than 7.5 per cent for luminosity and less than 5 per cent for radius. For a solar metallicity of Z = 0.02 these errors are less than 3 per cent for luminosity and 1.2 per cent for radius.