Ursa Major I Dwarf

From Wikipedia, the free encyclopedia

Ursa Major I Dwarf
Observation data (J2000 epoch)
Constellation Ursa Major
Right ascension 10h 34m 52.8s[1]
Declination +51° 55′ 12″[1]
Distance 330 kly (100 kpc)[citation needed]
Type dSph
Other designations
UMa I dwarf,[1] Ursa Major I dSph[1]
See also: Galaxy, List of galaxies

Ursa Major I Dwarf (UMa I dSph) is a dwarf spheroidal galaxy orbiting the Milky Way galaxy. The discovery by Beth Willman et al. was announced in 2005.

Being a small dwarf galaxy, it measures only a few thousand light-years in diameter. As of 2006, it is the second least luminous galaxy known (discounting dark galaxies such as VIRGOHI21 in the Virgo cluster of galaxies), to the Boötes Dwarf (absolute magnitude -5.7). The absolute magnitude of the galaxy is only -6.75, meaning that it is less luminous than some stars, like Deneb in the Milky Way. It is comparable in luminosity to Rigel. It was described to be similar to the Sextans Dwarf Galaxy. Both galaxies are ancient and metal-deficient.

It is located at a distance of about 330,000 light-years from the Earth. That is about twice the distance to the Large Magellanic Cloud, the largest and most luminous satellite galaxy of the Milky Way.

There was another object called Ursa Major Dwarf, discovered by Edwin Hubble in 1949. It was designated as Palomar 4. Due to its peculiar look, it was temporary suspected to be either a dwarf spheroidal or elliptical galaxy. However, it was later confirmed to be a very distant (about 360,000 ly) globular cluster belonging to our galaxy.

Contents

[edit] Sources

[edit] External links

[edit] See also

[edit] References

  1. ^ a b c d NASA/IPAC Extragalactic Database. Results for Ursa Major dSph. Retrieved on 2006-11-27.
v • d • e
The Milky Way
Location
The Milky Way Galaxy
Galactic core
Spiral arms
Satellite galaxies
Other