Ursa Minor

Tuesday 19 September 2017 - 22:03:10 Posted by  Bobby
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 Mythology of Ursa Minor

Ursa Minor contains the north celestial pole. By chance, there is a moderately bright star, known as Polaris (or the north Pole Star), about 1 degree from the pole. Navigators have long reconized that when looking at Polaris one is facing almost due north. Ursa Minor's main stars form a shape known as the Little Dipper, while the stars Beta and Gamma Ursae Minoris (Kochab and Pherkad), in the dipper's bowl, are known as the guardians of the Pole. Ursa Minor is named after a nymph who nursed the infant Zeus, although it is not clear why she is depicted as a bear.

 The Facts

  • Depiction: The Lesser Bear
  • Pronounced: ER-sah MY-ner
  • Genitive: Ursae Minoris
  • Abbreviation: UMi
  • Highest in the Sky: May to June
  • Size Ranking: 56th
  • Coverage Area: 256 Sq. Degrees
  • Right Acension: 15 hours
  • Declination: 70°
  • Visibility: 90°N to 0°S

 Notable Objects

  • Alpha Ursae Minoris: Cepheid variable star
  • NGC 3172: Polarissima Borealis
  • NGC 6217: Barred spiral galaxy

 Named Stars

  • Polaris, Alpha Ursae Minoris
  • Kochab, Beta Ursae Minoris
  • Pherkad Major, Gamma Ursae Minoris
  • Yildun, Delta Ursae Minoris

 Best Viewed Objects/Stars

Alpha Ursa Minoris (Polaris)

 The north Pole Star and the brightest star in the constellation, a yellow-white supergiant of magnitude 2.0. It is in fact a Cepheid variable, although its fluctuations in magnitude are so slight they cannot be detected with the naked eye. A small telescope shows an unrelated 8th-magnitude companion.

Gamma Ursae Minoris (Pherkad)

 An optical double star with components that are divisible with the naked eye or binoculars. Gamma itself is a blue-white giant star of magnitude 3.0, 480 light-years away. Its partner, 11 Ursae Minoris, is an orange giant, of magnitude 5.0, 390 light-years away.

Eta Ursae Minoris

 An optical double star. It is a white star of magnitude 5.0 lying 97 light-years away. The naked eye and binoculars show a wide companion, 19 Ursae Minoris, of magnitude 5.5, which is almost seven times farther away than the primary.

Ursa Minor
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