Looks like I'm fielding the astronomy numbers today. Ok, look at my response to the 7.5 days question. The stars are separated by 0.07 AU (distance Earth to Sun in our system). The center of gravity's closer to the more massive star, so let's say the center of mass is 1/4(0.07 AU) from the larger star. Assume a circular orbit (not a bad assumption). Then, v = 1/4*2PiR/(t) = 2*Pi*(1/4*0.07AU*1.15x10^11 m/AU)/4*(7 days*24*60*60) = 390,000 m/s = 3.9*10^5 m/s, a tiny fraction of c, which is 3*10^8 m/s. Fast, not that fast. 0.001 c

Using Kepler's 3rd Law, a^3 = p^2, with a = average orbital separation in AU (Earth to Sun distance), and p the orbital period in years: a = (7/365)^(2/3) = 0.07 AU. 1 solar radius is about 0.0046 AU. Go to the original paper here: http://www.sciencemag.org/content/early/2012/08/27/science.1228380.abstract and you see the larger star is about the size of our Sun, the smaller star 1/3 the size. 0.07 AU/0.0046(AU per radius) = 15.2 Solar radius separation between the stars. So, close but not close to overlapping.

Ok, this writer clearly isn't a scientist. They say that 84% of the light of the system comes from the brighter star, and 1% from the dimmer. That's all the light, right?...84 + 1 != 100 If you read the original NASA article, they said the brighter star is 84% as bright as our Sun and the dimmer one 1% as bright as our Sun. *sigh*