APOD: 2019 September 3 - Unusual Signal Suggests Neutron Star Destroyed by Black Hole

Good morning, Rallypoint. Today's Astronomy Picture of the Day (APOD) is titled "Unusual Signal Suggests Neutron Star Destroyed by Black Hole." The short video clip (0:20) is based on data collected by observatories in the United States and Europe. What did they collect? Gravitational waves. Gravitational waves are 'ripples' in the fabric of space-time caused by some of the most powerful processes in the universe - colliding black holes, exploding stars, and even the birth of the universe itself. Albert Einstein predicted the existence of gravitational waves in 1916, derived from his general theory of relativity. The first direct detection of gravitational waves occurred on September 14, 2015 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in the United States.

Fast forward to August 14, 2019. When the core of a star undergoes gravitational collapse at the end of its life, its surviving protons and electrons are scrunched together into a neutron star. Neutron stars cram so much matter into city-sized sphere perhaps 20 kilometers (12 miles) across that a sugar-cube-sized amount of this material would weigh more than 1 billion tons. The LIGO detected the expected oscillating pattern of gravitational waves resulting from the destruction of a neutron star by a black hole. Since this is the first direct detection of such an event, there is not much to compare it to. This video clip represents in visible light what such an event might have looked like.