NGC 4993: The Galactic Home of an Historic Explosion
Image Credit: NASA & ESA
Explanation: That reddish dot -- it wasn't there before. It's the dot to the upper left of galaxy
NGC 4993's center, do you see it? When scanning the large field of possible locations of an optical counterpart to the unprecedented
gravitational wave event GW170817 in August, the appearance of this
fading dot quickly became of historic importance. It pinpointed GW170817's exact location, thereby enabling humanity's major telescopes to examine the first ever
electromagnetic wave counterpart to a
gravitational wave event, an event giving strong evidence of being a
short gamma-ray burst kilonova, the element-forming explosion that occurs after
two neutron stars merge. The
featured image of
lenticular galaxy NGC 4993 by Hubble shows the
fading dot several days after it was discovered.
Analyses,
continuing, include the
physics of the explosion, what heavy
elements formed, the similarity of the speeds of gravitational radiation and light, and calibrating a
new method for determining the distance
scale of our universe.
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