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NGC 4993
NGC 4993 (also catalogued as NGC 4994 in the New General Catalogue) is a lenticular galaxy located about 140 million light-years away in the constellation Hydra. It was discovered on 26 March 1789 by William Herschel and is a member of the NGC 4993 Group.
NGC 4993 was the site of GW170817, a collision of two neutron stars, the first astronomical event detected in both electromagnetic and gravitational radiation, a discovery given the Breakthrough of the Year award for 2017 by the journal Science. The detection of gamma-ray burst GRB 170817A simultaneous with the gravitational wave event, for example, provided the first direct confirmation that binary neutron star collisions generate short gamma-ray bursts.
NGC 4993 has several concentric shells of stars and a large dust lane—with a diameter of approximately a few kiloparsecs—which surrounds the nucleus and is stretched out into an "s" shape. The dust lane appears to be connected to a small dust ring with a diameter of ~330 ly (0.1 kpc). These features in NGC 4993 may be the result of a recent merger with a gaseous late-type galaxy that occurred about 400 million years ago. However, Palmese et al. suggest that the galaxy involved in the merger was a gas-poor galaxy.
NGC 4993 has a dark matter halo with an estimated mass of 193.9×1010 M☉.
NGC 4993 has an estimated population of 250 globular clusters.
The luminosity of NGC 4993 indicates that the globular cluster system surrounding the galaxy may be dominated by metal-poor globular clusters.
NGC 4993 has a supermassive black hole with an estimated mass of roughly 80 to 100 million solar masses (8×107 M☉).
The presence of weak O III, NII and SII emission lines in the nucleus of NGC 4993 and the relatively high ratio of [NII]λ6583/Hα suggest that NGC 4993 is a low-luminosity AGN (LLAGN). The activity may have been triggered by gas from the late-type galaxy as it merged with NGC 4993.
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NGC 4993
NGC 4993 (also catalogued as NGC 4994 in the New General Catalogue) is a lenticular galaxy located about 140 million light-years away in the constellation Hydra. It was discovered on 26 March 1789 by William Herschel and is a member of the NGC 4993 Group.
NGC 4993 was the site of GW170817, a collision of two neutron stars, the first astronomical event detected in both electromagnetic and gravitational radiation, a discovery given the Breakthrough of the Year award for 2017 by the journal Science. The detection of gamma-ray burst GRB 170817A simultaneous with the gravitational wave event, for example, provided the first direct confirmation that binary neutron star collisions generate short gamma-ray bursts.
NGC 4993 has several concentric shells of stars and a large dust lane—with a diameter of approximately a few kiloparsecs—which surrounds the nucleus and is stretched out into an "s" shape. The dust lane appears to be connected to a small dust ring with a diameter of ~330 ly (0.1 kpc). These features in NGC 4993 may be the result of a recent merger with a gaseous late-type galaxy that occurred about 400 million years ago. However, Palmese et al. suggest that the galaxy involved in the merger was a gas-poor galaxy.
NGC 4993 has a dark matter halo with an estimated mass of 193.9×1010 M☉.
NGC 4993 has an estimated population of 250 globular clusters.
The luminosity of NGC 4993 indicates that the globular cluster system surrounding the galaxy may be dominated by metal-poor globular clusters.
NGC 4993 has a supermassive black hole with an estimated mass of roughly 80 to 100 million solar masses (8×107 M☉).
The presence of weak O III, NII and SII emission lines in the nucleus of NGC 4993 and the relatively high ratio of [NII]λ6583/Hα suggest that NGC 4993 is a low-luminosity AGN (LLAGN). The activity may have been triggered by gas from the late-type galaxy as it merged with NGC 4993.