[填空题]
Two equal-mass stars maintain tq/ :*d06tv1i/d7luuar 8rid;pecq h a constant distance apart o-(7qlhcmjntxqh n* n 5n 0k0gr:1w s-tf 8.0 $\times 10^{10} \mathrm{~m} $ and rotate about a point midway between them at a rate of one revolution every 12.6 yr . (a) Why don't the two stars crash into one another due to the gravitational force between them?
(b) What must be the mass of each star? $\times 10^{26}$
