Auriga (constellation)

Auriga (the charioteer), is a constellation of the northern hemisphere. Its location is easy: just look over Orion. A pentagon of bright stars is seen, among which Capella (α Aurigae) stands out.

Notable features

Constellation Auriga AlltheSky.com

The constellation's brightest star, Capella (α Aurigae), is a multiple star 42 light years distant, whose main components are two yellow giants of spectral type G8III and G1III. They move along a nearly circular orbit with an orbital period of 104 days. The two giants are accompanied by another, much dimmer binary, made up of two red dwarfs.

The second brightest star is β Aurigae, named Menkalinan, a triple system made up of two almost identical white subgiants (of type A1IV) separated by only 0.08 au, and a red dwarf furthest away that completes the system.

Almaaz (ε Aurigae) is a peculiar binary whose orbital period is approximately 27 years, producing an eclipse of about 18 months duration. The visible star is a white supergiant, the type of the companion star being unknown. ζ Aurigae (officially named Saclateni) is also an eclipsing binary consisting of a luminous orange giant and a bluish-white main sequence star of type B8V. The orbital period of this binary is 2.66 years. Both Almaaz and Saclateni are at a rare stage in binary evolution, as the components are in a short and active evolutionary phase.

Among the variables of the constellation, it is worth mentioning the variables Mira R Aurigae, U Aurigae and NV Aurigae; the latter is surrounded by a circumstellar envelope where maser emission of SiO—a common feature of oxygen-rich AGB stars—, water, and OH has been detected. Another interesting variable is AE Aurigae, a very hot blue star of the spectral type O9.5Ve with a temperature of around 33,000 K. It illuminates a cloud of dust and gas (IC 405) that it is passing through at high speed and its brightness fluctuates. irregularly, being classified as Orion variable. At the opposite extreme, UU Aurigae is a cool carbon star with a temperature of only 2760 K. Surrounding it is a layer of dust composed mainly of amorphous carbon and silicon carbide (SiC), as well as a rich outer shell. in carbon that extends up to 300 times the stellar radius. On the other hand, IQ Aurigae is a variable Alpha2 Canum Venaticorum, one of the bluest and hottest in this class. Observations made with the Chandra Observatory have shown that, in the X-ray region, the luminosity of IQ Aurigae is three orders of magnitude higher than that of Cor Caroli (α² Canum Venaticorum), star of similar characteristics.

Regarding planetary systems, WASP-12 is located in Auriga, a distant yellow star with a planet (WASP-12b) separated only 0.023 AU from the star. It is a "hot Jupiter" type planet that completes one orbit around the star in just over a day. Its short period, together with the fact that WASP-12 is a hot star, means that its equilibrium temperature reaches 2516 K, which makes it one of the planets that receives a greater amount of electromagnetic radiation. Likewise, HD 49674 —officially called Nervia— is a yellow dwarf of type G5V with a planet whose mass is equal to or greater than twice that of Neptune. Its orbital period is less than 5 days.

Open volume M36, distant 4300 light years.

Three objects from the Messier catalog are located in Auriga, M36, M37 and M38, all of them open clusters. M36, discovered by Giovanni Battista Odierna in the 17th century, contains at least 60 stars, the brightest being type B2 and 9th magnitude. Being very young—it has an estimated age of 25 million years—it has no red giants. M37 lies at an uncertain distance between 3,600 and 4,700 light-years from Earth and contains a total of 500 stars with a dozen red giants. The metallicity of this cluster is similar to or slightly higher than that of the Sun. The last of the clusters, M38, is 220 million years old and its brightest star is a yellow supergiant. Although visually the open cluster NGC 1907 is close to M38, there is no physical relationship between the two, since they are have formed in different parts of the galaxy.

Main Stars

The ε Aurigae system during an eclipse (art print).

• α Aurigae (Capella), of magnitude 0.08, is the brightest star of constellation and the brightest sixth star in the night sky. It is a multiple star composed of two binary stars.
• β Aurigae (Menkalinan), second brightest constellation star with magnitude 1,90, is actually a triple system formed by two white subgiants and a red dwarf.
• δ Aurigae, an orange giant of magnitude 3.72 to 140 light years away.
• ε Aurigae (Almaaz or Haldus), eclipsing variable star whose brightness oscillates between magnitude +3.0 and +3.8 in a cycle of about 27.1 years.
• Aurigae (Saclateni or Azaleh), an eclipsing variable with a period of 972 days.
• MIL Aurigae, blue star of magnitude 3,17.
• θ Aurigae, the third brightest star with magnitude 2,65, a binary star composed of a white star and a yellow dwarf separated 3.5 seconds of arc.
• ι Aurigae (Hassaleh), bright orange giant of magnitude 2.69.
• λ Aurigae, nearby yellow subgiant of magnitude 4,70.
• . Aurigae, yellow-orange giant of magnitude 3,97 to 215 light years.
• π Aurigae, bright red giant and irregular variable whose brightness varies between magnitude 4,24 and 4.34.
• τ Aurigae, yellow giant of magnitude 4,52.
• Aurigae, a red giant of magnitude 4.74.
• Aurigae, red supergigant of magnitude 4,97.
• /25070/5 Aurigae, sun analog to 54 light years away.
• ω Aurigae, large binary star whose components are separated 4.5sec of arc.
• 9 Aurigae (V398 Aurigae), Gamma Doradus variable of magnitude 4,98.
• 14 Aurigae (KW Aurigae), multiple star containing a Delta Scuti variable and a hot white dwarf.
• 19 Aurigae, white luminous giant of magnitude 5.05.
• 45 Aurigae, spectroscopic binary of magnitude 5.35.
• R Aurigae, variable Mira whose brightness varies between magnitude 6.7 and 13.9 in a period of 458 days.
• T Aurigae (Nova Aurigae 1892), nova that reached a magnitude of 3,8 in 1892.

Flame star Nebula (IC 405) around AE Aurigae (HD 34078).

• RT Aurigae, strained variable with variable brightness between magnitude 5,00 and 5.82 in a period of 3.73 days.
• Aurigae, carbon star and semi-regular variable whose brightness varies between magnitude 4.90 and 7.00.
• WW Aurigae, 5,82 eclipsing binary with a period of 2,53 days.
• AB Aurigae, Orion variable with a dust disk around it.
• AE Aurigae, variable blue star of spectral type O9.5 V, located inside the IC 405 gas nebula (also called the Flaming Star Nebula).
• GM Aurigae, a star of only 1 million years of age where there is evidence of planet formation.
• IQ Aurigae, variable star Alfa2 Canum Venaticorum, one of the hottest in this kind of variables.

Data chart of the Spitzer space telescope showing the molecules present on the planet WASP-12 b.

• NO Aurigae, red supergiant and irregular variable whose brightness varies between magnitude 6.1 and 6.3.
• NV Aurigae, distant variable Look of type M10.
• QY Aurigae, red dwarf binary at 20,0 light years away; it is the star of Auriga closest to the Solar System.
• V362 Aurigae, red supergigante and irregular variable of average magnitude 7.32.
• V394 Aurigae, a double star composed of a red giant of magnitude 6.08 and a white-yellow star of magnitude 10.3.
• V538 Aurigae, orange dwarf at 40 light years accompanied by a distant red dwarf.
• Gliese 246, hot white dwarf distant 50 light years.
• WASP-12, star with an extra-solar planet extra-hot (WASP-12b). Its orbital period is only 1.09 days.

Deep Sky Objects

Open cluster M37, which brings together a total of 500 stars.

• M36, open cluster of at least 60 stars gathered in a compact area. It is 4300 light years from Earth. Like M37 and M38, it was discovered by Giovanni Battista Odierna before 1654. AR: 05h 36m 06.0s Dec: +34°08'00" (Epoca 2000).
• M37, open cluster containing about 150 stars of magnitude 12.5 or lower and about 500 stars in total. He's an estimated age of 300 million years. Of magnitude 5,6, it is the brightest of the three clusters discovered by Odierna. AR: 05h 52m 24.0s Dec: +32°33'00" (Epoca 2000).
• M38, diffuse open cluster, northwest of M36, distant 4200 light years. AR: 05h 28m 42.0s Dec: +35°50'00" (Epoca 2000).
• NGC 1664, 30-40 star open cluster at the limit with Pegasus constellation.
• IC 410, tenuous emission nebula that surrounds the open cluster NGC 1893. It is approximately 2200 light years away.
• IC 2149, peculiar planetary nebula of elongada structure. It is at an approximate distance of 1100 paras.
• HB 9, VRO 42.05.01 and SNR G182.4+04.3, supernova remains; the first is 1750 light years.

Mythology

Image of the constellation of the Auriga or Cochero. Attention: the image is inverted

This constellation has several versions of its origin in Greek mythology:

In one, it is about Myrtilus, son of Hermes and Fetusa, driver of Oenomaus. The latter's daughter, Hippodamia, had many suitors but her father, to get rid of them, challenged them to a chariot race. What his opponents did not know was that his horses were divine and always won. The punishment for defeat was death. One day Pelops appeared, with whom the young Hippodamia immediately fell in love, and together they bribed Myrtilus to lose the race. The charioteer changed the iron nails of the king's chariot for wax ones, so that during the race they came loose and the chariot was destroyed. In the accident Enómao died dragged by the horses. After the victory, Pelops killed Myrtilus by throwing him into the sea and the charioteer in his fall cursed Pelops' race. Hermes put it in the firmament.

Another version relates that it represents Ericthonio, born from the semen of Hephaestus that impregnated Gaea when he tried to rape Athena. The boy was educated by Athena, invented the chariot and was named by Zeus because of his admiration that Ericthonio had competed with Helios.

In other versions, this constellation was identified with Troquilo, Oenomaus, Bellerophon, Cilas or Hippolytus.

The people of the Marshall Islands featured Auriga in the myth of Dümur, which tells the story of the creation of the sky. Antares in Scorpio represents Dümur, the eldest son of the mother of the stars, and the Pleiades represent his youngest son. The mother of the stars, Ligedaner, is represented by Capella; she lived on the island of Alinablab. She told her children that the first to reach an eastern island would become the King of the Stars, and she asked Dümur to let her into her canoe. She refused, as did each of her children, except for Pleiades. Pleiades won the race with the help of Ligedaner, and became King of the Stars. In other parts of the central Caroline Islands, Capella was called Jefegen uun (variations include efang alul, evang-el-ul, and iefangel uul), meaning "north of Aldebaran". Different names for Auriga and Capella were noted in Eastern Pacific societies. In Pukapuka, the modern Charioteer figure was called Te Wale-o-Tutakaiolo ("The House of Tutakaiolo") in the Society Islands it was called Faa-nui ("Great Valley"). Capella itself was called Tahi-anii ('Unique Ruler') in the Societies. Hoku-lei was the name of Capella, but may have been the name of the entire constellation; the name means "Crown of Stars" and refers to one of the wives of the Pleiades, named Makalii.