The Ursa Minor Dwarf is a

dwarf spheroidal galaxy A dwarf spheroidal galaxy (dSph) is a term in astronomy applied to small, low-luminosity galaxies with very little dust and an older stellar population. They are found in the Local Group as companions to the Milky Way and to systems that are com ...

, discovered by A.G. Wilson of the

Lowell Observatory Lowell Observatory is an astronomical observatory in Flagstaff, Arizona, United States. Lowell Observatory was established in 1894, placing it among the oldest observatories in the United States, and was designated a National Historic Landmark ...

, in the United States, during the

Palomar Sky Survey Palomar may refer to: Places * Any of several locations in San Diego County, California: ** Palomar Mountain ** Palomar Observatory, located on Palomar Mountain ** Palomar College in San Marcos, California ** Palomar Medical Center in Escondido, ...

in 1955. It appears in the

Ursa Minor Ursa Minor (Latin: 'Lesser Bear', contrasting with Ursa Major), also known as the Little Bear, is a constellation located in the far northern sky. As with the Great Bear, the tail of the Little Bear may also be seen as the handle of a ladle, h ...

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

, and is a

satellite galaxy A satellite galaxy is a smaller companion galaxy that travels on bound orbits within the gravitational potential of a more massive and luminous host galaxy (also known as the primary galaxy). Satellite galaxies and their constituents are bound ...

of the

Milky Way The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye ...

. The galaxy consists mainly of older stars and seems to house little to no ongoing star formation. Its centre is around 225,000 light years distant from

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

Evolutionary history

In 1999, Kenneth Mighell and Christopher Burke used the

Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope that was launched into low Earth orbit in 1990 and remains in operation. It was not the first space telescope, but it is one of the largest and most versa ...

to confirm that the Ursa Minor dwarf galaxy had a straightforward evolutionary history with a single burst of

star formation Star formation is the process by which dense regions within molecular clouds in The "medium" is present further soon.-->interstellar space

that lasted around 2 billion years and took place around 14 billion years ago, and that the galaxy was probably as old as the Milky Way itself.

References

External links

* * {{Sky, 15, 09, 08.5, +, 67, 13, 21, 200000 Dwarf galaxies Dwarf elliptical galaxies Local Group Milky Way Subgroup Ursa Minor (constellation) 09749 54074 ?

Evolutionary history

See also

References

External links