Leo V (dwarf galaxy)

For other uses, see Leo V (disambiguation).

Leo V is a dwarf spheroidal galaxy situated in the Leo constellation and discovered in 2007 in the data obtained by the Sloan Digital Sky Survey.^[2] The galaxy is located at a distance of about 180 kpc from the Sun and moves away from the Sun with the velocity of about 173 km/s.^[2] It is classified as a dwarf spheroidal galaxy (dSph) meaning that it has an approximately spherical shape with the half-light radius of about 130 pc.^{[3][note 1]}

Leo V Dwarf Galaxy[1]
Observation data (J2000 epoch)
Constellation	Leo
Right ascension	11h 31m 9.6s[1]
Declination	+02° 13′ 12″[1]
Distance	585 kly (180 kpc)[2] 570 ± 30 kly (175 ± 9 kpc)[3]
Apparent magnitude (V)	16 ± 0.4[3]
Characteristics
Type	DSph[2]
Apparent size (V)	5.2 ± 1.2′[3]
Other designations
Leo V,[1] PGC 4713563

Leo V is one of the smallest and faintest satellites of the Milky Way—its integrated luminosity is about 10,000 times that of the Sun (absolute visible magnitude of about −5.2 ± 0.4),^{[note 1]} which is much lower than the luminosity of a typical globular cluster.^[3] However, its mass is about 330 thousand solar masses, which means that Leo's V mass to light ratio is around 75. A relatively high mass to light ratio implies that Leo V is dominated by dark matter.^[4] The stellar population of Leo V consists mainly of old stars formed more than 12 billion years ago.^[2] The metallicity of these stars is also very low at [Fe/H] ≈ −2.0 ± 0.2, which means that they contain 100 times less heavy elements than the Sun.^[4]

The galaxy is located only 3 degrees away from another Milky Way satellite, Leo IV. The latter is also closer to the Sun by 20 kpc. These two galaxies may be physically associated with each other.^[2] There is evidence that they are connected by a star bridge.^[3]

Notes

1. From other sources the absolute magnitude is about −4.3 and the half-light radius of 40 pc.^[2]