Editing Stellar evolution (section)

==Models==
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A stellar evolutionary model is a [[mathematical model]] that can be used to compute the evolutionary phases of a star from its formation until it becomes a remnant. The mass and chemical composition of the star are used as the inputs, and the luminosity and surface temperature are the only constraints. The model formulae are based upon the physical understanding of the star, usually under the assumption of hydrostatic equilibrium. Extensive computer calculations are then run to determine the changing state of the star over time, yielding a table of data that can be used to determine the [[evolutionary track]] of the star across the [[Hertzsprung–Russell diagram]], along with other evolving properties.<ref name=aass316_1_31>{{cite journal | last1=Demarque | first1=P. | last2=Guenther | first2=D. B. | last3=Li | first3=L. H. | last4=Mazumdar | first4=A. | last5=Straka | first5=C. W. |date=August 2008 | title=YREC: the Yale rotating stellar evolution code | journal=Astrophysics and Space Science | volume=316 | issue=1–4 | pages=31–41 | doi=10.1007/s10509-007-9698-y | bibcode=2008Ap&SS.316...31D | arxiv = 0710.4003 | isbn=9781402094408| s2cid=14254892 }}</ref> Accurate models can be used to estimate the current age of a star by comparing its physical properties with those of stars along a matching evolutionary track.<ref name=ryan__norton2010>{{harvtxt|Ryan|Norton|2010|page=79|loc="Assigning ages from hydrogen-burning timescales"}}</ref>