The galaxy is filled with twins — pairs of stars that travel through space together, tethered by their gravitational pull. The most impressive pair yet confirmed is in a gigantic stellar nursery. Combined, the two stars are almost 200 times the mass of the Sun. NGC 3603 A1 is about 25,000 light-years away, in the southern constellation Carina. Astronomers recently combed through years of observations of the system made by Hubble Space Telescope. That allowed them to determine the masses of the two stars with much greater accuracy than previous studies. The main star is 108 times the mass of the Sun, while its companion is 82 times the Sun’s mass — the heaviest binary system measured at high precision. Their mass isn’t the only impressive thing about the stars, though. Both of them are tens of thousands of degrees hotter than the Sun. And most impressive of all, they’re more than a million times brighter than the Sun. The stars are so close together that the bigger star is puffing out t
