The dazzling spiral galaxy in this Hubble Space Telescope image is UGC 5460, located about 60 million light-years away in the constellation Ursa Major. This striking image combines four different wavelengths of light, showcasing the galaxy’s central bar of stars, twisting spiral arms, and clusters of bright blue stars. In the upper left corner of the image, a much closer object appears—a star from our own galaxy, just 577 light-years away.
UGC 5460 has been home to two recent supernovae, SN 2011ht and SN 2015as. These stellar explosions made the galaxy a prime target for Hubble, which gathered data as part of three separate observing programs designed to study different types of supernovae.
SN 2015as was what’s known as a core-collapse supernova: a cataclysmic explosion that happens when the core of a star far more massive than the Sun runs out of fuel and collapses under its own gravity, initiating a rebound of material outside the core. Hubble observations of SN 2015as will help researchers understand what happens when the expanding shockwave of a supernova collides with the gas that surrounds the exploded star.
SN 2011ht might have been a core-collapse supernova as well, but it could also be an impostor called a luminous blue variable. Luminous blue variables are rare stars that experience eruptions so large that they can mimic supernovae. Crucially, luminous blue variables emerge from these eruptions unscathed, while stars that go supernova do not. Hubble will search for a stellar survivor at SN 2011ht’s location, and the explosion’s identity may be revealed at last.
