04h54m13.5s, −53° 21′40″| NGC 1705 | |
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NGC 1705. Credit: NASA.
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| Observation data (J2000 epoch) | |
| Constellation | Pictor |
| Right ascension | 04h54m 13.500s[1] |
| Declination | −53° 21′ 39.82″[1] |
| Redshift | 633 ± 6 km/s[2] |
| Distance | 16.6 ± 2.0 Mly (5.1 ± 0.6 Mpc)[3] |
| Grouporcluster | Dorado Group |
| Apparent magnitude (V) | 12.56±0.03[4] |
| Characteristics | |
| Type | SA0− pec[2] or BCD[3] |
| Apparent size (V) | 1′.86 × 1′.45[5] |
| Other designations | |
| PGC 16282[2] | |
NGC 1705 is a peculiar lenticular galaxy and a blue compact dwarf galaxy (BCD)[3] in the southern constellationofPictor, positioned less than a degree to the east of Iota Pictoris,[6] and is undergoing a starburst.[7] With an apparent visual magnitude of 12.6[4] it requires a telescope to observe. It is estimated to be approximately 17 million light-years from the Earth,[8] and is a member of the Dorado Group.[9]
This is a relatively isolated galaxy, with its nearest neighbors being more than 500 kpc distant. However, its neutral hydrogen disk shows a significant amount of warp, suggesting that the outer gas is still settling into place.[3] The mass models of the galaxy suggest the dominant source of mass is a dark matter halo.[10] It has a super star cluster located near the galactic center,[10] and shows strong galactic winds.[3] Designated NGC1750–1, this cluster has a maximum radius of 2.85±0.50 pc and is 12±6 Myr old.[11]
The major starburst activity is happening at the core of the galaxy, within the central ~150 pc, and this is providing the main ionizing source out to distance of ~1 kpc or more.[7] Over the last 10 million years it has added 5.7×105 M☉ worth of stars.[3] The younger stars in the galaxy with an age below a billion years have an estimated 6×107 M☉ and are mainly concentrated near the center, while the older star populations have 2.2×108 M☉ and form a more extended distribution. The total mass of neutral hydrogen in the galaxy is estimated at (2.2±0.2)×108 M☉.[10]
Media related to NGC 1705 at Wikimedia Commons
