page_title: Auriga (constellation)
section_title: Deep-sky objects
hierarchical_section_title: Auriga (constellation) / Features / Deep-sky objects
caption_attribution_description: English: Spitzer IRAC mosaic of NGC 1893 star-forming region. Red: 8µm; Green: 5.8µm; Blue: 3.6µm
context_page_description: Auriga is one of the 88 modern constellations; it was among the 48 constellations listed by the 2nd-century astronomer Ptolemy. It is north of the celestial equator. Its name is Latin for “ charioteer”, associating it with various mythological beings, including Erichthonius and Myrtilus. Auriga is most prominent during winter evenings in the northern Hemisphere, as are five other constellations that have stars in the Winter Hexagon asterism. Because of its northern declination, Auriga is only visible in its entirety as far as 34° south; for observers farther south it lies partially or fully below the horizon. A large constellation, with an area of 657 square degrees, it is half the size of the largest, Hydra.
  Its brightest star, Capella, is an unusual multiple star system among the brightest stars in the night sky. Beta Aurigae is an interesting variable star in the constellation; Epsilon Aurigae, a nearby eclipsing binary with an unusually long period, has been studied intensively. Because of its position near the winter Milky Way, Auriga has many bright open clusters in its borders, including M36, M37, and M38, popular targets for amateur astronomers.
context_section_description: The galactic anticenter is located about 3.5° to the east of Beta Aurigae. This marks the point on the celestial sphere opposite the location of the Galactic Center; hence, this region marks a less extensive and less luminous part of the dust band that forms the spiral arms of the Milky Way. Auriga has many open clusters and other objects because the Milky Way runs through it. The three brightest open clusters are M36, M37 and M38, all of which are visible in binoculars or a small telescope in suburban skies. A larger telescope resolves individual stars. Three other open clusters are NGC 2281, lying close to ψ⁷ Aurigae, NGC 1664, which is close to ε Aurigae, and IC 410 (surrounding NGC 1893), a cluster with nebulosity next to IC 405, the Flaming Star Nebula, found about midway between M38 and ι Aurigae. AE Aurigae, a runaway star, is a bright variable star currently located within the Flaming Star Nebula.
  M36 (NGC 1960) is a young galactic open cluster with approximately 60 stars, most of which are relatively bright; however, only about 40 stars are visible in most amateur instruments. It is at a distance of 3,900 light-years and has an overall magnitude of 6.0; it is 14 light-years wide. Its apparent diameter is 12.0 arcminutes. Of the three open clusters in Auriga, M36 is both the smallest and the most concentrated, though its brightest stars are approximately 9th magnitude. It was discovered in 1749 by Guillaume Le Gentil, the first of Auriga's major open clusters to be discovered. M36 features a 10-arcminute-wide knot of bright stars in its center, anchored by Struve 737, a double star with components separated by 10.7 arcseconds. Most of the stars in M36 are B type stars with rapid rates of rotation. M36's Trumpler class is given as both I 3 r and II 3 m. Besides the central knot, most of the cluster's other stars appear in smaller knots and groups.
  M37 (NGC 2099) is an open cluster, larger than M36 and at a distance of 4,200 light-years. It has 150 stars, making it the richest cluster in Auriga; the most prominent member is an orange star that appears at the center. M37 is approximately 25 light-years in diameter. It is the brightest open cluster in Auriga with a magnitude of 5.6; it has an apparent diameter of 23.0 arcminutes. M37 was discovered in 1764 by Charles Messier, the first of many astronomers to laud its beauty. It was described as "a virtual cloud of glittering stars" by Robert Burnham, Jr. and Charles Piazzi Smyth commented that the star field was "strewed  [sic]...with sparkling gold-dust". The stars of M37 are older than those of M36; they are approximately 200 million years old. Most of the constituent stars are A type stars, though there are at least 12 red giants in the cluster as well. M37's Trumpler class is given as both I 2 r and II 1 r. The stars visible in a telescope range in magnitude from 9.0 to 13.0; there are two 9th magnitude stars in the center of the cluster and an east to west chain of 10th and 11th magnitude stars.
  M38 is a diffuse open cluster at a distance of 3,900 light-years, the least concentrated of the three main open clusters in Auriga; it is classified as a Trumpler Class II 2 r or III 2 r cluster because of this. It appears as a cross-shaped or pi-shaped object in a telescope and contains approximately 100 stars; its overall magnitude is 6.4. M38, like M36, was discovered by Guillaume Le Gentil in 1749. It has an apparent diameter of approximately 20 arcseconds and a true diameter of about 25 light-years. Unlike M36 or M37, M38 has a varied stellar population. The majority of the population consists of A and B type main sequence stars, the B type stars being the oldest members, and a number of G type giant stars. One yellow-hued G type star is the brightest star in M38 at a magnitude of 7.9. The brightest stars in M38 are magnitude 9 and 10. M38 is accompanied by NGC 1907, a smaller and dimmer cluster that lies half a degree south-southwest of M38; it is at a distance of 4,200 light-years. The smaller cluster has an overall magnitude of 8.2 and a diameter of 6.0 arcminute
caption: A picture of NGC 1893 obtained by the Spitzer Space Telescope. An association of recently formed stars is surrounded by the nebula IC 410.
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