Capricorn (Constellation)

Capricornus (the half-fish goat) is one of the constellations of the Zodiac, commonly called Capricorn, especially in astrology. Although sometimes depicted as a goat, a fish tail is usually attached to it.

Notable features

Capricornus constellation. AlltheSky.com

The brightest star in the constellation is δ Capricorni, called Deneb Algedi, a white star 38.6 light years distant. It is a spectroscopic binary and an eclipsing variable with an orbital period of only 24.5 hours. In addition, it is a metallic line (Am) star—its spectrum features strong absorption lines for some metals and weak ones for others, such as calcium—, being one of the brightest within this group. In this same constellation, Nashira (γ Capricorni), is also an Am star and an Ap star. Its bolometric luminosity is 25 times greater than solar luminosity and its mass is equivalent to 2.44 solar masses.

β Capricorni (Dabih) is the second brightest star in the constellation. It is a complex stellar system with five components, the main star being a luminous orange giant of spectral type K0II. In addition, another component of the system is a mercury-manganese star with very high levels of some metals: levels of platinum, gold, mercury and bismuth are 100,000 times higher than on the Sun.

ζ Capricorni, occasionally called Yen or Marakk, is a yellow supergiant of spectral type G4Ib distant 385 light-years. This star is the archetypal barium star, a class of stars rich in barium and other contributed heavy elements by a white dwarf with which it forms a binary system. In the case of ζ Capricorni, the companion white dwarf completes one orbit around the giant every 2,300 days.

θ Capricorni, occasionally called Dorsum, is a white main-sequence star of type A1V 65 times more luminous than the Sun that is located 162 light-years away. Closer to us—48 light-years—ψ Capricorni is a main sequence star of type F5V 3.8 times more luminous than the Sun and with a metallicity similar to that of the Sun.

Among the variables of the constellation, it is worth highlighting the carbon stars R Capricorni and RT Capricorni. The second, of spectral type C6.4, is a semiregular SRB variable whose brightness varies between apparent magnitude +6.8 and +8.0 over a period of 423 days.

Capricorn has several stars with extrasolar planets. Distant 28.8 light-years from Earth, HR 7722 (Gliese 785) is a K2V-type orange dwarf with two planets orbiting 0.3 and 1.2 AU from the star. HD 204313 is a yellow dwarf of type G5V also with two planets, one of them very not very massive, its minimum mass being equal to 5.5% of the mass of Jupiter. Another yellow dwarf in the constellation, HD 202206, forms a binary system with a red dwarf; A brown dwarf orbits this pair at a distance of 2.4 AU.

Image of HCG 87 Hubble Telescope

The constellation's most prominent deep space object is the globular cluster M30. It is approximately 27,100 light-years from Earth and has a diameter of about 93 light-years. It follows a retrograde orbit around the galactic center, suggesting that it was acquired from a satellite galaxy rather than formed within the Via. Milky. Another globular cluster in this constellation is Palomar 12; distant 63,600 light-years, it is a relatively young cluster, about 30% younger than most globular clusters in the Milky Way.

On the other hand, NGC 6907 is a spiral galaxy of grand design and the most prominent member of a small group of galaxies known as the NGC 6907 Group. Other members of this group include NGC 6908, IC 4999, and IC 5005. NGC 6907 is 118 million light-years from Earth.

More distant—about 400 million light-years—is the compact group of galaxies HCG 87, made up of a large spiral galaxy, an elliptical galaxy, and a second, smaller spiral galaxy.

Main Stars

• α1 Capricorni and α2 Capricorni (Al Giedi or Algiedi), double optic composed of two yellow and orange stars. α¹, the less bright of the two, is at least 700 light years away, six times further away than α².
• β Capricorni (Dabih), visually appears as a blue and yellow binary star, separated 3.5 minutes of arc. Each of these components is, in turn, a multiple star system.
• γ Capricorni (Nashira), white star of magnitude 3.69. Its spectrum presents strong absorption lines of some metals, being classified as Am Star.
• δ Capricorni (Deneb Algedi), the brightest star of constellation with magnitude 2.85, is a quadruple star system. The main star is a giant or white subgigant.
• ε Capricorni, variable Gamma Cassiopeiae and star with wrap.
• γ Capricorni, of magnitude 3.77, archetype of barium star, a class of rich stars not only in this element but also in other heavy elements.
• θcorni (Armus), a binary star of magnitude 4,86 whose components are separated 0,30 seconds of arc.
• θ Capricorni, white star of magnitude 4,06 located at 158 light years.
• ι Capricorni, yellow giant of magnitude 4,30.
• κ Capricorni, of magnitude 4.74, is also a yellow giant.
• μ Capricorni, white star of magnitude 5.08.
• ν Capricorni (Alshat), white-azulada star of magnitude 4,76.
• φ Capricorni o φ2 Capricorni, white-yellow star of magnitude 5.85.
• ρ Capricorni, white star of magnitude 4.77.
• τ2 Capricorni, star system formed by two white-blue stars separated 0.4 seconds of arc and a third star discovered by concealment.
• Capricorni, possibly variable red giant of magnitude 5,17.
• /25070/ Capricorni (Pazan), yellow star of magnitude 4,14 something warmer and brighter than the Sun, located 48 light years.
• ω Capricorni, red giant of magnitude 4,12.
• 20 Capricorni (AO Capricorni), variable Alpha2 Canum Venaticorum of magnitude 6.26.
• 36 Capricorni (b Capricorni), an orange giant of magnitude 4.50.
• 37 Capricorni, white-yellow star of magnitude 5,69.
• 41 Capricorni, an orange giant of magnitude 5.25.

• 42 Capricorni, binary star and variable RS Canum Venaticorum of magnitude 5,18.
• 46 Capricorni (c Capricorni), yellow supergiant of magnitude 5.09.
• 50 Capricorni, white-yellow star of magnitude 7.01.
• RT Capricorni, carbon star of average magnitude 7,18.
• AG Capricorni (47 Capricorni), red and semi-regular giant whose brightness ranges between magnitude 5.9 and 6.14.
• BE Capricorni, massive Be star of magnitude 6.45.
• HD 202206, yellow dwarf with a brown dwarf and an extrasolate planet.
• HD 204313, yellow dwarf with two planets, one of them low-mass.
• HR 7722 (Gliese 785), orange dwarf at 28.8 light years away; it has an extrasolate planet.
• HIP 102152, solar but more evolved twin, with an age of 8200 million years.

Deep Sky Objects

Glybular cluster M30.

• M30 (NGC 7099), a prominent globular cluster that is located 4th to the southeast of γ Capricorni. It's 27 100 light years from the Sun. The cluster follows a retrograde orbit through the inner galactic halo, suggesting that it was trapped from a satellite galaxy and not formed within the Milky Way. It is easy to observe even with a small telescope.
• Palomar 12, distant globular cluster.
• NGC 6907, coiled spiral galaxy.
• NGC 7103, elliptical galaxy.

Mythology

Image of the constellation of Capricornus.

Capricornus represents Amaltea half goat, half fish, who cared and fed Zeus when this was small, in whom Rea trusted to protect him from his father Cronos.

According to some, Amalthea was a nymph from Arcadia; to others, she was a nymph in the form of a goat. Amalthea and her daughter Adrastea raised Zeus on honey and milk. Amalthea had admirable horns that grew and spilled nectar and ambrosia, and when one of them broke off, she filled it with fruit to offer it to Zeus. It is the famous horn of Amalthea, a symbol of abundance and happiness. From that event, Zeus placed her in one of the constellations in the sky.

Another version of the Capricorn myth says that Pan, god of hunters and shepherds, is chased by the serpent Typhon and, to escape, he throws himself into the Nile River, turning into an ibex fish on the back and a billy goat. in the other. Zeus admires this stratagem and raises her to the heavens.

Text references

General references

• _ Catasterism (Καταστερισμο).
  • 27: Capricorn: (As a result, γόκερως, κάν; Capricornus, Caper, Pan): a son of Egypt who grew up with Zeus and then helped him in the Titanoquia giving him a snail whose sound put the Titans in flight; or the Pan himself; or the Amaltea goat.
    • Latin text in Google Books; electronic facsimile.
      • Greek text on the Internet Archive; electronic facsimile.

• HIGINO: Poetry astronomy (Astronomica).
  • 28: Capricorn.
    • Translation of Mary Grant into English (1960) on Theoi website.