Crater 2 | |
---|---|
Observation data ( J2000.0 epoch) | |
Constellation | Crater [1] |
Right ascension | 11h 49m 14.400s 177.310°±0.03° [1] |
Declination | −18° 24′ 46.80″ −18.413°±0.03° [1] |
Heliocentric radial velocity | 88 km/s [2] |
Galactocentric velocity | -74 km/s [2] |
Distance | 383,000 ly (117.5 kpc) [1] |
Apparent magnitude (V) | 12.15 mag [1] |
Absolute magnitude (V) | −8.2±0.1 mag [1] |
Characteristics | |
Type | dSph [1] |
Apparent size (V) | 62.4
′ (rh=31.2
′ ± 2.5
′)
[1] 6,950 ly (2,132 pc) rh=1066pc ± 84pc [1] |
Notable features | 4th largest satellite galaxy to Milky Way [1] |
Crater 2 is a low-surface-brightness dwarf satellite galaxy of the Milky Way, [1] located approximately 380,000 ly from Earth. Its discovery in 2016 revealed significant gaps in astronomers' understanding of galaxies possessing relatively small half-light diameters and suggested the possibility of many undiscovered dwarf galaxies orbiting the Milky Way. [3] Crater 2 was identified in imaging data from the VST ATLAS survey. [3]
The galaxy has a half-light radius of ~1100 pc, making it the fourth largest satellite of the Milky Way. [1] It has an angular size about double of that of the moon. [3] [4] Despite the large size, Crater 2 has a surprisingly low surface brightness, implying that it is not very massive. [5] In addition, its velocity dispersion is also low, suggesting it may have formed in a halo of low dark matter density. [6] Alternatively, it may be a result of tidal interactions with it and larger galaxies, such as the Milky Way and the Large Magellanic Cloud, [5] but according to some simulations, this would not explain the relatively large size. [6] This unusually low velocity dispersion was predicted using Modified Newtonian Dynamics, an alternative to the dark matter hypothesis. [7] This prediction was later confirmed by observations. [8]
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Crater 2 | |
---|---|
Observation data ( J2000.0 epoch) | |
Constellation | Crater [1] |
Right ascension | 11h 49m 14.400s 177.310°±0.03° [1] |
Declination | −18° 24′ 46.80″ −18.413°±0.03° [1] |
Heliocentric radial velocity | 88 km/s [2] |
Galactocentric velocity | -74 km/s [2] |
Distance | 383,000 ly (117.5 kpc) [1] |
Apparent magnitude (V) | 12.15 mag [1] |
Absolute magnitude (V) | −8.2±0.1 mag [1] |
Characteristics | |
Type | dSph [1] |
Apparent size (V) | 62.4
′ (rh=31.2
′ ± 2.5
′)
[1] 6,950 ly (2,132 pc) rh=1066pc ± 84pc [1] |
Notable features | 4th largest satellite galaxy to Milky Way [1] |
Crater 2 is a low-surface-brightness dwarf satellite galaxy of the Milky Way, [1] located approximately 380,000 ly from Earth. Its discovery in 2016 revealed significant gaps in astronomers' understanding of galaxies possessing relatively small half-light diameters and suggested the possibility of many undiscovered dwarf galaxies orbiting the Milky Way. [3] Crater 2 was identified in imaging data from the VST ATLAS survey. [3]
The galaxy has a half-light radius of ~1100 pc, making it the fourth largest satellite of the Milky Way. [1] It has an angular size about double of that of the moon. [3] [4] Despite the large size, Crater 2 has a surprisingly low surface brightness, implying that it is not very massive. [5] In addition, its velocity dispersion is also low, suggesting it may have formed in a halo of low dark matter density. [6] Alternatively, it may be a result of tidal interactions with it and larger galaxies, such as the Milky Way and the Large Magellanic Cloud, [5] but according to some simulations, this would not explain the relatively large size. [6] This unusually low velocity dispersion was predicted using Modified Newtonian Dynamics, an alternative to the dark matter hypothesis. [7] This prediction was later confirmed by observations. [8]
{{
cite journal}}
: CS1 maint: numeric names: authors list (
link)