Carina

Carina (the Keel) is a southern constellation that is part of the ancient constellation of Argo Navis (the Ship Argo). The International Astronomical Union divided it into four components: Carina (the Keel), Vela (the Sail), Puppis (the Popa) and Pyxis (the Compass).

Notable features

Constellation of Carina

Canopus (α Carinae) is the second brightest star in the firmament with apparent magnitude -0.72. Its name comes from the mythological character Canopus, a navigator of Menelaus, king of Sparta. It is a luminous giant or supergiant white-yellow whose luminosity is 13,300 times greater than that of the Sun. Distant 309 light years, it is the brightest star intrinsic within a radius of 700 light years of the solar system.

The second brightest star in the constellation (β Carinae) is called Miaplacidus and is a white subgiant of spectral type A2IV that is 111 light-years away; inside it is finishing the fusion of hydrogen and its nucleus must be formed almost exclusively by inert helium. It is followed in brightness by ε Carinae, called Avior, a binary star whose components are an orange giant and a bluish-white star of similar luminosity. Aspidiske (ι Carinae), a white supergiant of type A7Ib, is 690 light-years away and has a luminosity equivalent to 4,900 Suns. It is the fourth-brightest star in Carina.

υ Carinae is a double star observable with a small telescope: the components of this system are a white supergiant and a bluish-white star whose orbital period exceeds 20,000 years. The Diamond Cross is an asterism formed by Miaplacidus, θ Carinae, υ Carinae and ω Carinae.

Deserves special attention Eta Carinae, one of the most massive stars in the galaxy found within the Carina Nebula (NGC 3372). It is a stellar system that contains at least two stars whose combined luminosity is five million times that of the Sun. In the past it was a star of the fourth magnitude, but in 1837 it increased drastically in brightness marking the beginning of a great eruption and, between on March 11 and 14, 1843, it even surpassed Canopus in brilliance.

Among the variable stars, Carina is home to one of the most prominent Cepheids in the night sky, l Carinae or HD 84810, whose brightness oscillates between magnitude 3.35 and 4.06 over a period of 35,556 days. Another Carina cepheid, U Carinae, has spectral type G0Ib and has a period of 38,809 days, one of the longest periods for this type of variable. Instead, S Carinae is a Mira variable with a period of 150.28 days, one of the shortest within its group.

AG Carinae has very different characteristics, one of the most luminous stars in the Milky Way that emits a million times more electromagnetic radiation than the Sun. It is a luminous blue variable that is in a phase of rapid transition between a supergiant blue and a Wolf-Rayet star. Closely similar to AG Carinae is HR Carinae, also a luminous blue variable with a mass almost 40 times that of the Sun.

Other variables in the constellation are PP Carinae —Gamma Cassiopeiae variable whose rotation speed exceeds 285 km/s—, χ Carinae —Beta Cephei type B3IV variable— and A Carinae, an eclipsing binary with an orbital period of 195 days composed of a luminous giant of type G6II and its companion of type A1V. It is also an eclipsing binary WR 22, its components being a Wolf-Rayet star of type WN 7 and a blue star of type O9V; their respective masses with 72 and 26 times greater than that of the Sun.

Several stars with planets are located in this constellation. HD 63765, named Tapecue according to the IAU, is a yellow dwarf of type G9V with an extrasolar planet whose orbital period is 358 days. Similarly, Gliese 422 is a red dwarf with a planet, but in this case with a much shorter orbital period (just over 20 days).

NGC 2808, globular cluster with three different star populations.

Since the Milky Way passes through Carina, the constellation contains several open clusters such as NGC 2516, NGC 3532, and IC 2602. The latter, known as the Southern Pleiades, consists of about 74 stars, the most prominent being θ Carinae, a blue main sequence star of spectral type B0Vp; its age does not match that of the cluster and it is considered a blue straggling star. IC 2602 lies 479 light-years from Earth. NGC 2516, called the Southern Manger, contains two fifth-magnitude red giants. For its part, NGC 3532 has about 150 stars distributed in an unusual way, since they form an ellipse around a dark central area.

In contrast, NGC 2808 is a very massive and compact globular cluster (class I) that lies 31,200 light-years from Earth and 36,200 light-years from the galactic center. It is notable because star formation has taken place in three distinct phases in the cluster's early life; all stars were born within 200 million years, very early, in this 10.2 billion-year-old cluster.

Image of the Carina Nebula (NGC 3372) obtained from the European Southern Observatory

The Carina or Keel Nebula (NGC 3372) is a large nebula that surrounds several open star clusters and massive stars such as the aforementioned Eta Carinae. Among others, it contains the systems WR 22 —a binary formed by a Wolf-Rayet star and a blue star of the O9V type— and HD 93129, made up of at least three very bright blue stars, the main component being a blue supergiant of the O2If type. *. Carina OB1 is a stellar association on the fringes of this nebula which contains some of the most massive and luminous stars in the Milky Way.; among these, the red supergiants RT Carinae, CK Carinae and IX Carinae stand out for their size, with diameters 1000 times larger than that of the Sun. NGC 3372 is one of the largest known diffuse nebulae.

Lastly, NGC 3579 is a distant emission nebula 9000 light-years away that hosts the eclipsing binary EM Carinae. Formed by two stars of type O7.5V(f), its orbital period is 3.4143 days. The two components have a mass of 23.3 and 21.8 solar masses.

Main Stars

• α Carinae (Canopus, or Canopo), second brightest star in the sky, of magnitude -0.72, is a white-yellow supergigante 310 light years from us. Although it is a southern hemisphere star, it can be seen from the African coast of the Mediterranean Sea.
• β Carinae (Miaplacidus), the second most brilliant star of constellation (magnitude 1,67), a white subgigant.
• ε Carinae (Avior), of magnitude 1,86, whose name was assigned in the 1930s when it was created The Air Almanaca sailing ship used by British air forces.
• Cristian Carinae (Eta Carinae), one of the most massive stars in the universe, with an enormous luminosity of about four million times that of the Sun, and with an estimated mass of 100 to 150 times the mass of our local star.

Image of Eta Carinae obtained with Hubble space telescope.

• θ Carinae, inside the cluster of the same name.
• ι Carinae (Aspidiske), of magnitude 2,21, a white supergiant at 690 light years.
• ♫ Carinae, of magnitude 2,92, binary star that can be solved with binoculars. The separation between the components is 5 seconds of arc.
• χ Carinae (Drys), blue subgiant of magnitude 3,46 distant 387 light years.
• h Carinae (HD 83183), white-blue luminous giant of magnitude 4,09.
• I Carinae (HD 90589) and HD 68456, white-yellow stars of magnitude 4,00 and 4.76 respectively.
• HD 84810 (l Carinae), variable star cefeida, whose magnitude ranges from 3,28 to 4,18 in a cycle of 35,54 days. It is one of the brightest cefeidas visible at the naked eye.
• b2 Carinae (HD 77370) white-yellow star of magnitude 5.16.
• f Carinae (V334 Carinae), white-azulada star of magnitude 4.51.
• S Carinae, variable star Mira whose brightness varies between magnitude 4.5 and 9.9 in a cycle of 149.49 days.
• U Carinae, variable gloss cefeide between magnitude 5,72 and 7.02 with a period of 38,726 days.
• RT Carinae, red supergiant of magnitude 8,55 with a diameter 1090 times larger than the solar diameter.
• VY Carinae, whose brightness varies between magnitude 6.787 and 8.05 in a period of 18.99 days.
• AG Carinae and HR Carinae, two blue luminous variables; the first one is a million times brighter than the Sun.
• EM Carinae, 8,52 eclipsing binary composed of two hot and massive stars.
• CK Carinae and IX Carinae, red supergiant whose respective diameters are 1000 and 920 times larger than the Sun.
• PP Carinae (p Carinae), star Be of magnitude 3.36.
• QX Carinae, binaria eclipsante of magnitude 6,64.

Carina Nebula around the star WR 22.

• V337 Carinae (q Carinae), bright orange and irregular variable giant whose brightness varies between magnitude 3.36 and 3.44.
• V382 Carinae, yellow supergigante and strained variable.
• V415 Carinae (A Carinae), an eclipsing binary whose primary is a bright yellow giant.
• BO Carinae and V528 Carinae, red supergiants and irregular variables of respective average magnitudes 7,18 and 6,75.
• LHS 288 and GJ 1128, distant red dwarfs 15.6 and 21.3 light years respectively.
• HD 93129 and HD 93250, massive star systems in the Carina nebula; the main component of HD 93129 is one of the most luminous stars known.
• A1 (WR 43a), located in NGC 3603, is one of the most massive binary systems known.
• WR 20a and WR 22, two massive binary systems. The first is composed of two stars of Wolf-Rayet and the second, of magnitude 6.42, is observable at the naked eye.
• Sher 25, distant blue supergiant who is thought to be about to explode as supernova.
• WD 0800-533, white dwarf that can form a binary system with a red dwarf.

Deep Sky Objects

Image of NGC 3372, obtained by the Astronomical Observatory Los Molinos, OALM.

NGC 2867 planetary nebula.

• Nebula de la Quilla or Nebula de Carina (NGC 3372), which surrounds the massive stars Eta Carinae, HD 93129 and HD 93250. The nebula is at an estimated distance of 6500 to 10 000 light years from Earth. Within its limits is the star association Carina OB1, which in turn includes the Collinder clusters 228, NGC 3293, NGC 3324, IC 2581, Trumpler 14, Trumpler 15 and Trumpler 16. Within this great nebula there is also a smaller figure (rodeing to the Eta Carinae itself) that receives the name Nebula del Homúnculo. AR: 10h 43m 48.0s Dec: -59°52′00′′ (Epoch 2000).
• NGC 2516, occasionally called Southern Winter due to its similarity to Cancer's M44 constellation, is a large open cluster that is about 1300 light years away. It may be part of the Scorpius-Centaurus Star Association. AR: 07h 58m 18.0s Dec: -60°52′00′′ (Epoch 2000).
• NGC 2808 is a large globular cluster, one of the most massive in our galaxy. It has stars of three different generations. AR: 09h 12m 00.0s Dec: -64°52′00′′ (Epoch 2000).
• NGC 3114, open cluster. AR: 10h 02m 42.0s Dec: -60°07′00′′ (Epoch 2000).
• NGC 3293, open cluster with more than one hundred distant stars around 9000 light years.
• NGC 3532 is also an open cluster with about 150 stars. It was the first object observed by the Hubble space telescope in May 1990.
• NGC 3603 is a distant open cluster in which there are several massive and hot Wolf-Rayet stars, such as the A1 system.
• Theta Carinae or Pléyades del Sur (IC 2602), which contains about 74 stars, being the most prominent θ Carinae. It is the third brightest cluster in the sky and is about 550 light years away. AR: 10h 43m 12.0s Dec: -64°24′00′′ (Epoch 2000).
• NGC 2867, planetary nebula at 1.2° NNE of Aspidiske (ι Carinae), whose central star is a Wolf-Rayet star.
• MSH 11-61A and MSH 11-62, remains of mixed and composite supernova morphology, respectively.
• Carina dwarf, small satellite galaxy of the Milky Way.

Mythology

The dismantled constellation of Argo Navis.

The Argonauts, in the poem by Apollonius of Rhodes, were the companions who traveled with Jason on the expedition whose objective was to find the Golden Fleece. The name Argonauts comes from the ship Argo.

Pelias became king of Yolcos after dethroning and subsequently imprisoning Aeson. This, fearful that his son Jason (who was the rightful heir to the throne) would be killed, sent him to the centaur Chiron's cave, where he received instruction until he could return to Yolcos and claim his right to the throne.

On his journey to Yolcos, Jason lost one of his sandals, and upon appearing before Pelias, he remembered an ancient oracle that warned that someone with only one sandal would come down the mountain to dethrone and kill him. Pelias agreed to return the throne to Jason, but demanded that he fulfill an alleged request to return the Golden Fleece to his place of origin.

Jason accepted the commission and asked Argos to build a boat, which possessed the gift of speech and prophecy. He later formed the crew with the bravest young men of those times.

The Argonauts set out from the coast of Págasas, and on their way through the island of Lemnos (inhabited by women) they united with them with the idea of conceiving male children. They passed through Samothrace arriving at the land of the Doliones, where their king Cícico welcomed them. However, when they left, the winds carried them back to the coast, and by mistake they confronted their former hosts and King Cycicus and his court were killed. On the shores of Mysia, the nymphs seized Hylas, so Hercules and Polyphemus left the ship to come to their aid and the journey continued without them. Passing through the land of the blind fortune teller Fineo, they freed him from the Harpies, and he, in gratitude, gave them the key to avoid the Cyanean rocks, which destroyed any ship that dared to pass between them.

After these and other adventures, the expedition reached the kingdom of Aeetes. Jason paid a visit to the monarch and requested the delivery of the Golden Fleece. The king, to deliver it to him, asked him in return to tame the bulls with bronze hooves, and to plow the field and sow dragon teeth that he himself would give him.

The sorceress Medea, daughter of Aeetes, who fell in love with Jason, offered to help him as long as Jason married her. She gave him a magical ointment to apply to her body, and a shield, with which he would be protected against fire and iron. She warned him that by planting the dragon's teeth, they would become soldiers that would kill him. She also instructed him to throw stones without being seen to confuse them, thus making them fight and kill each other.

Jason accomplished these tasks successfully, but Aeetes reneged on his promise because he suspected his daughter had aided the hero. Then Jason, helped by Medea, put the guardian dragon to sleep, seized the Golden Fleece and they fled. When King Aeetes discovered the escape and theft of the Golden Fleece, he set out in search of him. Medea, to delay him, killed her younger brother Apsirtos, and tearing up his corpse, she threw her members into the sea one by one. In this way, Aeetes wasted time in pursuit, collecting the body parts of his beloved son.

On their return, as they passed through Anthemoesa, the island of the sirens, the Argonauts were protected from their songs by one of their members, Orpheus, a legendary musician from Thrace, with his melodious lyre and voice. They then reached Crete, where they confronted and killed the giant Talos with the help of Medea's spells.

When returning to Yolcos, bringing with him the Golden Fleece, Jason learned that Pelias had murdered all his relatives, and that he also refused to hand over the throne to him. Medea, in order to eliminate the king, then conspired so that Pelias's own daughters would kill him. Jason assumed the throne, and together with Medea they reigned in Yolcos. Years later, they conceived a son, entrusting his education to the centaur Chiron.