Aries (constellation)
Aries (the ram) is one of the constellations of the zodiac; It lies between the constellations of Pisces to the west and Taurus to the east.
Notable features
α Arietis is called Hamal and is the brightest star with magnitude 2.01. It is an orange giant of spectral type K2III whose radius, as befits a star of its characteristics, is almost 15 times larger than the solar radius. In 2011, the presence of a planet —with a mass at least 1.8 times that of Jupiter— was detected in orbit around this star. The second brightest star in Aries is Sheratan (β Arietis), a spectroscopic binary consisting of a white main-sequence star and a yellow Sun-like dwarf. The orbit of this binary is markedly eccentric (ε = 0.88), which causes the separation between the two stars to vary between 0.08 AU (20% of the distance between Mercury and the Sun) and 1.2 AU (20% more than the distance between Earth and the Sun). It is followed in brightness by 41 Arietis —formally called Bharani—, a star of spectral type B8V, whose effective temperature is 11,900 K and its luminosity 160 times greater than that of the Sun. It does not have a Bayer designation, since in in the past it was part of the constellation Musca Borealis, today discarded, being its brightest star.
Aries contains several interesting double stars, most notably γ Arietis, ε Arietis, and λ Arietis. γ Arietis, known as Mesarthim, is composed of two white stars that take more than 5,000 years to complete one orbit around their common center of mass. One of the components is an Ap variable star Alpha2 Canum Venaticorum. For their part, the two components of ε Arietis are A3V type stars whose orbital period is 704 years; an orange dwarf of type K0V, much more distant, takes about 12,400 years to complete one orbit around the inner pair. Finally, λ Arietis is a wide binary consisting of a main sequence star (type A7V or F0V) and a yellow dwarf similar to the Sun. The separation between both stars is equal to or greater than 1480 AU.
Among the constellation variables are the variables Mira R Arietis and U Arietis. The brightness of the first fluctuates between magnitude 7.1 and 14.3 over a period of 185.67 days, while that of the second fluctuates between magnitude 7.2 and 15.8 over a period of 371,1 days. On the other hand, V Arietis is a carbon star of type C-H3.5, as well as a CH star of 3621 K temperature. Another variable of interest is SX Arietis, a chemically peculiar star —specifically, it shows strong absorption lines from silicon— with a temperature of 12,420 K and 2.6 solar masses.
Another variable is TT Arietis, one of the most peculiar in the night sky. Classified as a cataclysmic variable, it is a binary system where the primary component is a hot white dwarf accompanied by a much cooler star of spectral type M3.5. The surface of the white dwarf is thought to be heated by a high rate of accretion, reaching a temperature close to 80,000 K. The orbital period of the system is only 3.3 hours.
Aries also contains two red dwarf stars—Teegarden's Star and TZ Arietis—that are among the 40 closest stars to the solar system. At the time of its discovery (2003), the parallax of Teegarden's Star was measured as 0.43 ± 0.13 arc seconds, which placed it only 7.8 light-years away, making it the third-most star. close to our Solar System. However, later studies place this dim red dwarf at 12.5 light-years away. Exoplanets have been discovered in both stars. Specifically, Teegarden's Star has two planets of a mass similar to Earth orbiting in the habitable zone of the star.
HD 12661 is a yellow dwarf of type G6V with two extrasolar planets; both are more massive than Jupiter and orbit 0.8 and 2.9 au from the star. Also of spectral type G6V, HIP 14810 has three planets in orbit around it; the innermost is a very massive "hot Jupiter" type planet.
As far as deep space is concerned, Aries is home to the galaxies NGC 772 and NGC 1156. NGC 772 is an unbarred spiral galaxy with a prominent bulge; the main arm, on the northwest side of the galaxy, contains several star-forming regions. In contrast, NGC 1156 is a dwarf irregular galaxy of apparent magnitude 11.7. Some pockets of gas within NGC 1156 rotate in the opposite direction to the rest of the galaxy, suggesting that there has been a close encounter with another galaxy. in the past.
Main Stars
- α Arietis (Hamal or Hemal), the brightest star of the constellation with magnitude 2,01, an orange giant surrounded by a beautiful group of stars.
- β Arietis (Sheratan), the second most bright with magnitude 2,64, spectroscopic binary of white color.
- γ Arietis (Mesarthim), of magnitude 3,88 is a binary star whose two white components are separated 8 seconds of arc. One of them is a slightly variable star.
- δ Arietis (Botein), giant orange star of magnitude 4,35.
- ε Arietis, binary star whose components are separated 1.5 seconds of arc.
- γ Arietis, white star of the main sequence of magnitude 4.88.
- η Arietis, white-yellow star of magnitude 5.24.
- ι Arietis, orange star of magnitude 5,11.
- λ Arietis, large binary with a separation of 37.4 seconds of arc.
- ρ3 Arietis, white star of magnitude 5.63.
- 14 Arietis, a white-yellow giant of magnitude 4,98.
- 19 Arietis, a red giant of magnitude 5.73.
- 26 Arietis (USA Arietis), white star of the main sequence and multi-period variable Delta Scuti.
- 27 Arietis, subgiant or yellow giant of magnitude 6,23.
- 29 Arietis, yellow dwarf of magnitude 6.00.
- 39 Arietis, an orange giant of magnitude 4,51, seventh brightest star of Aries.
- 41 Arietis (Bharani), a white-azulada star of magnitude 3,61; yet not having Bayer's name is the third brightest of the constellation.
- 51 Arietis, yellow dwarf located 69 light years away.
- 59 Arietis, yellow subgiver.
- U Arietis, variable star Mira whose brightness varies between 7.2 and 15.8 in a period of 371 days.
- V Arietis, carbon star and very poor CH star in metals.
- RZ Arietis (45 Arietis), red and semi-regular giant of magnitude 5.80.
- SX Arietis (56 Arietis), of magnitude 5,77, is the prototype of the variables bearing its name.
- TT Arietis, a cataclysmic variable whose nature is not well known; it usually has magnitude 10.5, but for long periods its brightness decreases to magnitude 15.
- TZ Arietis (Luyten 1159-16), red dwarf and brightening star also close to the Solar System, at 14.5 light years.
- UV Arietis (38 Arietis), Delta Scuti variable of magnitude 5,19.
- Teegarden Star, very tight red dwarf located about 12.5 light years from Earth.
- HD 12661, star of magnitude 7.44 with two extra-solar planets.
- HD 20367, yellow dwarf with an extrasolate planet.
- HIP 14810, yellow dwarf with three planets.
Deep Sky Objects
- NGC 772 AR: 01h 59m 18.0s Dec: +19°01'00" (Epoca 2000). Spiral Galaxy, to a degree of γ Arietis. It has several satellite galaxies, including NGC 770, which is about 113 000 light years away from NGC 772. Both are about 130 million light years from Earth.
- NGC 821, elliptical galaxy.
- NGC 877, distant intermediate spiral galaxy 160 million light years approximately. He is the most prominent member of a galactic group that bears his name.
- NGC 1156, irregular dwarf galaxy of apparent magnitude 11,7. Its galactic core is bigger than the average.
Mythology
Prixus and Hele are sons of Athamas, king of Thessaly, and Nephele. After being widowed, Atamante remarries Ino. Years later the kingdom suffers a stage of famine and the queen decides to sacrifice the brothers to end this fateful time. Hermes saves the children by giving them a winged ram, with wool or golden fleece, and endowed with the gift of speech. The children set off on him for Asia, saving their lives. During the trip Hele falls into the sea and drowns, giving his name to that marine region, which will be renamed Hellespont. Frixo arrives at Colchis, whose king Aeetes welcomes him and grants him Calcíope's daughter in marriage.
In gratitude to Aeetes, Phrixus sacrifices the ram and offers the fleece to the king, who consecrates it to Ares and hangs it from an oak tree in a forest dedicated to the god, guarded by a huge dragon and surrounded by fields where huge wild bulls. In gratitude Zeus placed Aries in the night sky.
According to some, Aries is a dim constellation because the golden fleece of the lamb stayed in Colchis.
Contenido relacionado
Triton (satellite)
Nicolaus Copernicus
Hamal