Corvus (constellation)
Constellation | |
70th) | |
Main stars | 4 |
---|---|
Bayer/Flamsteed stars | 10 |
Stars with planets | 3 |
Stars brighter than 3.00m | 3 |
Stars within 10.00 pc (32.62 ly) | 1 |
Brightest star | γ Crv (Gienah) (2.59m) |
Messier objects | 0 |
Meteor showers | Corvids Eta Corvids |
Bordering constellations | Virgo Crater Hydra |
Visible at latitudes between +60° and −90°. Best visible at 21:00 (9 p.m.) during the month of May. |
Corvus is a small
With an apparent magnitude of 2.59, Gamma Corvi—also known as Gienah—is the brightest star in the constellation. It is an aging blue giant around four times as massive as the Sun. The young star Eta Corvi has been found to have two debris disks. Three star systems have exoplanets, and a fourth planetary system is unconfirmed. TV Corvi is a dwarf nova—a white dwarf and brown dwarf in very close orbit.
History and mythology
In the
Corvus is associated with the myth of
In other cultures
In
Corvus was recognized as a constellation by several Polynesian cultures and used as a guide for ocean navigation. In the Marquesas Islands, it was called Mee; in Pukapuka, it was called Te Manu, and in the Society Islands, it was called Metua-ai-papa.[8] To Torres Strait Islanders, Corvus was the right hand (holding kupa fruit) of the huge constellation Tagai, a man fishing.[9]
The
Characteristics
Covering 184
Features
Stars
The German cartographer Johann Bayer used the Greek letters Alpha through Eta to label the most prominent stars in the constellation. John Flamsteed gave nine stars Flamsteed designations, while one star he designated in the neighbouring constellation Crater—31 Crateris—lay within Corvus once the constellation boundaries were established in 1930.[17] Within the constellation's borders, there are 29 stars brighter than or equal to apparent magnitude 6.5.[c][13]
Four principal stars, Delta, Gamma, Epsilon, and Beta Corvi, form a quadrilateral asterism known as "the "Spica's Spanker"[19] or "the Sail".[20][21] Although none of the stars are particularly bright, they lie in a dim area of the sky, rendering the asterism easy to distinguish in the night sky.[22] Gamma and Delta serve as pointers toward Spica. Also called Gienah, Gamma is the brightest star in Corvus at magnitude 2.59.[23] Its traditional name means "wing",[23] the star marking the left wing in Bayer's Uranometria.[17] 154±1 light-years from Earth,[24] it is a blue-white hued giant star of spectral type B8III that is 4.2+0.4
−0.3 times as massive,[25] and 355 times as luminous as the Sun.[23] Around 160+40
−30 million years old,[25] it has largely exhausted its core hydrogen and begun expanding and cooling as it moves away from the main sequence.[23] A binary star, it has a companion orange or red dwarf star of spectral type K5V to M5V that is about 0.8 times as massive as the Sun.[26] Around 50 astronomical units[d] distant from Gamma Corvi A, it is estimated to complete an orbit in 158 years.[25] Delta Corvi, traditionally called Algorab, is a double star divisible in small amateur telescopes. The primary is a blue-white star of magnitude 2.9, around 87 light-years from Earth.[24] An enigmatic star around 2.7 times as massive as the Sun, it is more luminous (65–70 times that of the Sun) than its should be for its surface temperature of 10,400 K, and hence is either a 3.2 million year-old very young pre-main sequence star that has not settled down to a stable main sequence life stage, or a 260-million-year-old star that has begun to exhaust its core hydrogen and expand, cool and shine more brightly as it moves away from the main sequence. Its spectral type is given as A0IV, corresponding with the latter scenario.[27] Warm circumstellar dust—by definition part of its inner stellar system—has been detected around Delta Corvi A.[28] Delta Corvi B is an orange dwarf star of magnitude 8.51 and spectral class K, also surrounded by circumstellar dust. A post T-tauri star, it is at least 650 AU distant from its brighter companion and takes at least 9400 years to complete an orbit.[29] Delta Corvi's common name means "the raven".[4] It is one of two stars marking the right wing.[17] Located 4.5 degrees northeast of Delta Corvi is Struve 1669, a binary star that is divisible into two stars 5.4" apart by small amateur telescopes,[30] 280 light-years from Earth. The pair, both white stars, is visible to the naked eye at magnitude 5.2; the primary is of magnitude 5.9 and the secondary is of magnitude 6.0.[4]
The raven's breast is marked by Beta Corvi (the proper name is Kraz
Named Alchiba,
Marking the raven's right wing is Eta Corvi,[17] a yellow-white main-sequence star of type F2V that is 1.52 times as massive and 4.87 times as luminous as the Sun. It is 59 light-years distant from our Solar System.[38] Two debris disks have been detected orbiting this star, one warm within 3.5 astronomical units and another out at ~150 astronomical units distant.[39][40] Zeta Corvi marks the raven's neck.[17] It is of apparent magnitude 5.21, separated by 7 arcseconds from the star HR 4691.[41] Located 420 ± 10 light-years distant,[24] it is a blue-white Be star of spectral type B8V, the presence of hydrogen emission lines in its spectrum indicating it has a circumstellar disc. These stars may be an optical double or a true multiple star system, with a separation of at least 50,000 astronomical units and the stars taking 3.5 million years to orbit each other. HR 4691 is itself double, composed of an ageing yellow-orange giant whose spectral type has been calculated at K0 or G3, and an F-type main-sequence star.[41]
31 Crateris (which was originally placed in Crater by Flamsteed) is a 5.26 magnitude star which was once mistaken for a
Close to Gamma Corvi and visible in the same binocular field is
Three star systems have confirmed planets. HD 103774 is a young yellow-white main-sequence star of apparent magnitude 7.12 that is 181 ± 5 light-years distant from Earth. It is 1.335 ± 0.03 times as massive and 3.5 ± 0.3 as luminous as the Sun. Variations in its radial velocity showed it was being orbited by a Neptune-sized planet every 5.9 days in 2013.[60] HD 104067 is an orange dwarf of spectral type K2V of apparent magnitude 7.93 that is 69 ± 1 light-years distant from Earth. Around 80% as massive as the Sun, it is orbited by a planet 3.6 times the mass of Neptune every 55.8 days.[61] WASP-83 has a planet around as massive as Saturn that orbits it every 5 days. It was discovered by its transit across the star in 2015.[62] A fourth star system has an unconfirmed planet. HD 111031 is a sunlike star of spectral type G5V located 101 ± 2 light-years distant from Earth.[24]
Deep-sky objects
Corvus contains no Messier objects. It has several galaxies and a planetary nebula observable with amateur telescopes.[70] The center of Corvus is home to a planetary nebula, NGC 4361.[70] The nebula itself resembles a small elliptical galaxy and has a magnitude of 10.3, but the magnitude 13 star at its centre gives away its true nature.[55] Corvus also contains the Stargate (asterism).
The
NGC 4027 is another member of the NGC 4038 group, notable for its extended spiral arm. Known as the Ringtail Galaxy, it lies close to 31 Crateris.[71] A barred spiral galaxy, its distorted shape is probably due to a past collision, possibly with the nearby NGC 4027A. NGC 4782 and NGC 4783 are a pair of merging elliptical galaxies in the northeastern part of the constellation, around 200 million light-years distant.[69]
Meteor showers
Two established meteor showers originate from within Corvus' boundaries. German astronomer Cuno Hoffmeister discovered and named the Corvids in 1937, after observing them between June 25 and July 2. They have not been seen since, nor was there evidence of a shower when previous records were examined. Hoffmeister noted the trajectory of the shower was similar to that of the comet 11P/Tempel–Swift–LINEAR, though this was not confirmed by Zhukov and colleagues in 2011. The shower has been tentatively linked with 4015 Wilson–Harrington.[75] In January 2013, the MO Video Meteor Network published the discovery of the Eta Corvids, assigning some 300 meteors seen between January 20 and 26.[76] Their existence was confirmed by data analysis later that year.[77]
Popular culture
In 1624, German astronomer Jakob Bartsch equated the constellation Argo Navis with Noah's Ark, linking Corvus and Columba to the crow and dove that feature in the story in Genesis.[78]
In Action Comics #14 (January 2013), which was published 7 November 2012, astrophysicist Neil deGrasse Tyson appears in the story, in which he determines that Superman's home planet, Krypton, orbited the red dwarf LHS 2520 in the constellation Corvus, 27.1 light-years from Earth. Tyson assisted DC Comics in selecting a real-life star that would be an appropriate parent star to Krypton, and picked the star in Corvus,[79][80] and which is the mascot of Superman's high school, the Smallville Crows.[81]
See also
- Corvus (Chinese astronomy)
Notes
- ^ Delporte had proposed standardizing the constellation boundaries to the International Astronomical Union, who had agreed and gave him the lead role.[15]
- ^ While parts of the constellation technically rise above the horizon to observers between the 65°N and 78°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.[13]
- ^ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.[18]
- ^ The distance between the Earth and the Sun is one astronomical unit.
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