Arp 104, also known as Keenan's system, is entry 104 in Halton Arp's Atlas of Peculiar Galaxies catalog for spiral galaxy NGC 5216 and globular galaxy NGC 5218.[2] The two galaxies are joined by a bridge of galactic material spanning 22 000 light years.[2][3]
Arp 104 | |
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![]() NGC 5216: The Keenan System, Arp 104 | |
Observation data (J2000[1] epoch) | |
Constellation | Ursa Major[2] |
Right ascension | 13h 32m 08.9s[1] |
Declination | +62° 44′ 02″[1] |
Redshift | 0.010817[1] |
Distance | 1.73 × 107[2][3] |
Apparent magnitude (V) | 14.0[4]/12.3[5] |
Characteristics | |
Type | E0/SBb-pec[6] |
Notable features | bridged[2] |
Other designations | |
Keenan's system[1][2] NGC 5216/NGC 5218[1][2] |
In 1790 William Herschel discovered the galaxies, and in 1926 they were studied by Edwin Hubble.[2] In 1935 Philip C. Keenan first published a paper about the bridge connecting the galaxies,[2][10] which was rediscovered in 1958 at the Lick and Palomar observatories.[2][3][11]
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