NGC 6902

NGC 6902 is an unbarred spiral galaxy located in the southern constellation of Sagittarius at an approximate distance of 124 million light-years (38.0 Mpc).^[6] NGC 6902 was discovered on September 2, 1836 by English astronomer John Herschel.^[9] In his New General Catalogue, Danish astronomer J. L. E. Dreyer described it as faint, considerably small, round, brighter middle.^[10][11] It is a member of the small NGC 6092 group of galaxies; the LGG 434 group.^[9]

ConstellationSagittarius

Right ascension20^h 24^m 28.067^s[3]

Declination−43° 39′ 12.42″^[3]

Redshift0.009300±0.000023^[4]

Quick facts Observation data (J2000 epoch), Constellation ...

NGC 6902
NGC 6902 imaged by SPECULOOS[1][2]
Observation data (J2000 epoch)
Constellation	Sagittarius
Right ascension	20h 24m 28.067s[3]
Declination	−43° 39′ 12.42″[3]
Redshift	0.009300±0.000023[4]
Heliocentric radial velocity	2793.9 km/s[5]
Distance	124 Mly (38.0 Mpc)[6]
Group or cluster	LGG 434
Apparent magnitude (V)	10.93±0.18[6]
Apparent magnitude (B)	11.64±0.18[6]
Characteristics
Type	SA(r)b[6]
Size	~334,800 ly (102.64 kpc) (estimated)
Apparent size (V)	3.55′ × 2.69′[7]
Other designations
IRAS 20210-4348, F20210-4348, 2MASX J20242813-4339127, Gaia DR2 6678974930431764096, NGC 6902, IC 4948, LEDA 64632, MCG -07-42-002, PGC 64632[8]

Close

The morphological classification of NGC 6902 is SA(r)b,^[6] indicating an unbarred spiral galaxy (SA) with an inner ring (r) and somewhat tightly wound arms (b). As the two arms extend outward, they transition into a complex system of filamentary arms. The galaxy has an angular size of 3.55′ × 2.69′ in the optical band.^[7] The galactic plane is inclined at an angle of 38±5° to the line of sight from the Earth. NGC 6902 has a high abundance of neutral hydrogen; about three times greater than a typical galaxy of this class.^[12] The ring structure is undergoing extensive star formation. Although classed as unbarred, there is a small bar of stars inside the ring.^[9]