Sunday, 14 June 2015

mass - What are the masses of the two stars (given the information provided)?

We can assume that the stars are equal in mass, and their orbits are circular



The orbital speed is 80000 m/s and at an orbital period of 10 months (or $2.628times 10^7$s) the length of the orbit is $2.1024times 10^{12}$ m or 14.05 AU The radius of the orbit therefore is $14.05/tau$ = 2.237AU.



The version of Keplers law given is $$T^2 =frac{a^3}{m_1+m_2}$$



substituting $T^2 =(10/12)^2 = 0.6944$ (divide by 12 to convert to years) and $a^3= 11.19$ gives $$m_1+m_2 = frac{11.19}{0.6944} = 16.12 mathrm{solar mass}.$$



Since $m_1=m_2$, the mass of each star is 8.06 solar masses, or $1.6times 10^{31}$kg

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