Sea-bream (constellation)

See also: Sea-bream

The Dorade is a Constellation of the Southern hemisphere. Only its star S more in north can be seen above 20° of northern latitude and it extends almost until the pole southern celestial.

The Sea-bream is far from luminous. None of its stars exceeds the fourth magnitude.

The most notable object of Sea-bream is on the other hand the Grand Cloud of Magellan, reaching magnitude 0,1.

History

The Sea-bream is one of the 11 constellations invented by the navigators Dutch Pieter Dirkszoon Keyser and Frederick de Houtman between 1595 and 1597. It was popularized by Johann Bayer during the publication of sound Uranometria in 1603. Its provision all in length also points out the “swordfish”, as it is sometimes called.

Observation of stars

; Localization of the constellation The Sea-bream is halfway between Canopus, of the Carène, and Achernar, terminus of the river Éridan. It is a little weaker than its neighbor the Réticule.

; Large cloud of Magellan The principal interest of this zone is the large cloud of Magellan, in the South of the constellation (and with horse on the limit with the Table).

The Nebula of the Tarantula is also visible with the naked eye, in the middle of the Cloud.

Principal stars

See also: List of stars of the Sea-bream

α  Doradus

The most brilliant star of the constellation, α  Doradus, reaches only magnitude 3,30. It is however easy to find, being located at a dozen degrees of Canopus (α  Carinae) in an area particularly low in stars.

Moved away of almost 180 light-years, α  Doradus is a bluish star of spectral Type A0, 120 times more brilliant than the Sun. It is also slightly variable (of type α ² Canum Venaticorum), passing from magnitude 3,26 with magnitude 3,30 in 2,95 days.

γ  Doradus

γ  Dor is a slightly variable star, its magnitude varying of some pourcents between 4,23 and 4,27 over two successive periods of 17,5 and 18,1 hours. This behavior resembles the variable of type δ Scuti, but the temperature of γ  Dor (7 000 K) is too weak to answer the same mechanism.

Other stars

β  Dorarus is a Variable céphéide, evolving/moving between magnitudes 3,46 and 4,08 in 9,8426 days.

R  Doradus is variable semi-regular, of which the magnitude passes from 4,8 to 6,6 over one period of approximately 338 days.

Celestial objects

The most notable object of Sea-bream is the Grand Cloud of Magellan (of which a part is also in the constellation of the Autel), a irregular Galaxie satellite of our Milky Way, distant 170.000 years light and reaching magnitude 0,1.

The Sea-bream also contains nebula NGC 2070, also named Nébuleuse of the Tarantula. Catalogued first of all like a star (30  Doradus), it was recognized like a nebula by Nicolas-Louis de Lacaille in 1751 - 1752. It is about part of the Large Cloud of Magellan, of a diameter of a thousand of years light, lodging a dozen Supergéante S in its center.

In addition, the south pole of the ecliptic is located in the constellation, close to the Large Cloud.

See too

  • List of stars of the Sea-bream

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