THE HYDRA CONSTELLATION — In an astronomical first, scientists detected light and gravity from what they believe was the collision of two ultra-compact dense neutron stars in galaxy NG 4993. <br /> <br />First detected in 2013, a kilonova is a class of supernova explosion resulting from two colliding neutron stars. <br /> <br />The Space Telescope Science Institute says each neutron in this case was no wider than Washington, D.C. Typically, they're between 6 and 12 miles in diameter. <br /> <br />The Institute added that the stars in question weighed between 10 percent and 60 percent more than our sun." <br /> <br />What followed the kilonova is unknown, but NASA astrophysicist Eleonora Troja told Space.com the cosmic explosion may have a formed a black hole.
