Ursa Major I dwarf galaxy

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Galaxy
Ursa Major I dwarf galaxy
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AladinLite
Constellation Big Bear
Position
equinox :  J2000.0 , epoch : J2000.0
Right ascension 10 h 34 m 52.8 s
declination 51 ° 55 ′ 12 ″
Appearance
Morphological type dSph  
Angular expansion 23 ′ × 12 ′
Physical data
Affiliation Local group  
Redshift 3.67  ·  10 −3  
Radial velocity (1101 ± 1) km / s  
distance (330,000 ± 10,000) ly /
(100,000 ± 3,000) pc
Absolute brightness −6.75 V mag
history
discovery Beth Willman et al.
Discovery date 2005
Catalog names

The Ursa Major I dwarf galaxy ( UMa I for short ) is a spheroid dwarf galaxy and satellite galaxy of the Milky Way in the constellation of the Great Bear . The discovery of the galaxy by Beth Willman et al. was announced in 2005 .

properties

Even among the dwarf galaxies that is UMa I still relatively small, with its few thousand light-years measured diameter . As of 2006 , it was the third weakest galaxy at all (if one ignores the so-called dark galaxies such as VirgoHI21 in the Virgo galaxy cluster ), measured by its absolute brightness .

Dwarf galaxy M V
Ursa Major II dwarf galaxy −3.8 m
Bootes-I dwarf galaxy −5.7 m
Ursa Major I dwarf galaxy −6.75 m

In other words, as a galaxy it is fainter than some individual stars in the Milky Way such as Deneb and roughly comparable in luminosity to Rigel . It shares some similarities with the Sextans dwarf galaxy . Both galaxies are very old and poor in metal .

The Ursa Major I dwarf galaxy is about 3.30 × 10 5 light years away, which is roughly twice the distance to the Large Magellanic Cloud .

Special

Another astronomical object discovered by Edwin Hubble as early as 1949 was also known as the Ursa Major Dwarf Galaxy . It was then later referred to as Palomar 4 . Due to its strange appearance, it was initially classified as a dwarf galaxy. In fact, at a distance of around 3.6 × 10 5 light years , Palomar 4 is the most widely known, distant globular cluster in our Milky Way.

additional

Individual evidence

  1. ↑ a b c d NASA / IPAC EXTRAGALACTIC DATABASE
  2. ↑ a b c d e f g Willman, Dalcanton, Martinez-Delgado, et al. (2005) " A New Milky Way Dwarf Galaxy in Ursa Major ", submitted to Astrophysical Journal Letters, on arXiv.org: astro-ph / 0503552
  3. ↑ Ursa Major Dwarf, Palomar 4 . In: Milky Way Globular Clusters . Retrieved April 16, 2005.

Web links

Commons : Greater Bear constellation  - Collection of images, videos and audio files