One of the constellations discovered late in the 16th century is Dorado. A small constellation in the southern hemisphere, Dorado was one of the constellations discovered by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman. However, the Dutch astronomer Petrus Plancius listed it in the 16th century and by the 17th and 18th century, the constellation was also known as Xiphias, the swordfish. In Spanish, Dorado means ‘dolphinfish’. The constellation is represented as the colourful dolphinfish which is found in tropical waters and not the goldfish found commonly in plants and aquaria. It belongs to the Johann Bayer family of constellations and is best visible in the month of January at 9 pm.
Some of the notable stars of this constellation include:
- a Doradus (Alpha Doradus): It is the brightest star in the constellation. Alpha Doradus is basically a binary star and is about 169 light years away. The star’s brightness varies from 3.26 to 3.30. The binary system of Alpha Doradus comprises of the primary star, a giant belonging to the spectral class and a sub giant. It has a visual magnitude of 3.8, whereas the companion has a magnitude of about 4.3.
- B Doradus (Beta Doradus): It is the second brightest star in the Dorado constellation. It is a Cepheid variable star, about 1,050 light years away from the earth. The brightness of Beta Doradus varies from 4.05 to 3.45.
- y Doradus (Gamma Doradus): It is basically a variable star in this constellation with a visual magnitude of 4.25. The star is about 66.2 light years away.
- δ Doradus (Delta Doradus): Delta Doradus has a visual magnitude of 4.34 and is about 145 light years away. It is known for being the Moon’s South Pole star.
- R Doradus (HD 29712): HD 29712 is basically a red giant star. It has a visual magnitude of about 5.40 and is about 178 light years away. It is believed to be the second largest star when observed from the earth. The brightness of HD 29712 fluctuates between 4.8 and 6.6.
- S Doradus: It is basically a hypergiant in this constellation and is also one of the brightest stars in the Large Magellanic Cloud. S Doradus is also one of the brightest stars known, but is not visible to the naked eye; this is because it is at a distance of 169,000 light years. The star has a visual magnitude of 9.565 whereas its brightness varies from 8.6 to 11.5.
- ζ Doradus (Zeta Doradus): It is basically a yellow–white main sequence star in Dorado. Zeta Doradus has a visual magnitude of 4.68 and is about 38 light years away from the earth.
- HE 0437–5439: It is basically an unbound hypervelocity star in this constellation which appears to be receding at a speed of 723 kilometres per second. HD 0437–5439 is believed to be about 30 million years old and is about 200, 000 light years away. It was initially discovered in the year 2005 by the observers at the European Southern Observatory. It has a visual magnitude of about 16.3.
Some notable deep sky objects are:
- Large Magellanic Cloud: It is an irregular galaxy which is also a satellite galaxy to the Milky Way. It is about 10 billion times the mass of the sun. Large Magellanic Cloud has a visual magnitude of about 0.9 and is about 157,000 light years away. It basically comprises of 700 open clusters, 400 planetary nebulae and 60 globular star clusters; it is also home to innumerable supergiant and giant stars. The galaxy is highly rich in dust and gas and is undergoing an intense star formation activity.
- Tarantula Nebula (30 Doradus): The Tarantula Nebula lies in the Large Magellanic Cloud. The nebula has a magnitude of 8 and is about 160,000 light years away. It is an exceptionally bright non–stellar object. It also contains a compact star cluster, which is mainly responsible for producing the energy, making it appear so bright.
- SNR 0509 -67.5: It is a supernova remnant located in the Large Magellanic Cloud. It is about 160,000 light years away. It is believed that SNR 0509–67.6 occurred about 400 years ago.
- SN 1987A: It basically was a supernova, which had occurred about 167,885 light years in the outer region of the Tarantula Nebula. It can be seen with a naked eye as it has a peak magnitude of 2.9.
- The Ghost Head Nebula (NGC 2080): In Dorado, the Ghost Head Nebula is a star forming region in the Large Magellanic Cloud. It is located to the south of the Tarantula Nebula. The nebula is about 160,000 light years away. The nebula has two distinct white patches called ‘the eyes of the ghost’.
- N44: It is basically an emission nebula located in the Large Magellanic Cloud. N44 is about 160,000–170,000 light years away from the earth. N44 has a super bubble structure, which is formed by the radiation pressure of a group comprising of about 40 bright blue–white stars, which is located near the nebula’s centre. It also consists of a smaller bubble structure inside.
- NGC 1566: In Dorado, NGC 1566 is the brightest galaxy. It is basically an intermediate spiral galaxy which is about 38.4 million light years away. NGC 1566 has a visual magnitude of 10.3.
- NGC 1850: In Dorado, NGC 1850 is basically an open cluster which was discovered by James Dunlop in 1826. The cluster has a visual magnitude of 9.0. It is notable because its stars are distributed as they would be in a globular cluster, but globular clusters are formed of old stars whereas NGC 1850 contains young stars.
Dorado lies in the first quadrant of the southern hemisphere and can be seen between latitudes +20° and -90°.
It occupies an area of 179 square degrees, making it the 72nd constellation in size.
There are no myths associated with this constellation. It is sometimes, referred to as the Swordfish Constellation or Xipias.
Dorado neighbours constellations such as Caelum, Horologium, Hydrus, Mensa, Pictor, Reticulum and Volans.
