Crater (constellation)

Coordinates: Sky map 11h 00m 00s, −16° 00′ 00″
Source: Wikipedia, the free encyclopedia.
Crater
Constellation
Eta Craterids
Bordering
constellations		Leo
Sextans
Hydra
Corvus
Virgo
Visible at latitudes between +65° and −90°.
Best visible at 21:00 (9 p.m.) during the month of April.

Crater is a small

Apollo and is perched on the back of Hydra
the water snake.

There is no

Crater 2 and NGC 3981, and a famous quasar
lie within the borders of the constellation.

Mythology

Old chart with various constellation figures overlaid onto stars
Corvus, Crater, and other constellations seen around Hydra, from Urania's Mirror (1825). Crater (centre) is depicted as a gold, double-handled cup with decorative filigree.

In the Babylonian star catalogues dating from at least 1100 BC, the stars of Crater were possibly incorporated with those of the crow Corvus in the Babylonian Raven (MUL.UGA.MUSHEN). British scientist John H. Rogers observed that the adjoining constellation Hydra signified Ningishzida, the god of the underworld in the Babylonian compendium MUL.APIN. He proposed that Corvus and Crater (along with the water snake Hydra) were death symbols and marked the gate to the underworld.[2] Corvus and Crater also featured in the iconography of Mithraism, which is thought to have been of middle-eastern origin before spreading into Ancient Greece and Rome.[3]

Crater is identified with a story from Greek mythology in which a crow or raven serves Apollo, and is sent to fetch water, but it delays its journey as it finds some figs and waits for them to ripen before eating them. Finally, it retrieves the water in a cup and takes back a water snake, blaming it for drinking the water.[4] According to the myth, Apollo saw through the fraud, and angrily cast the crow, cup, and snake into the sky.[5] The three constellations were arranged in such a way that the crow was prevented from drinking from the cup, and hence seen as a warning against sinning against the gods.[4]

Phylarchus wrote of a different origin for Crater. He told how the city of Eleusa near Troy was beset by plague. Its ruler Demiphon consulted an oracle which decreed that a maiden should be sacrificed each year. Demiphon declared that he would choose a maiden by lottery, but he did not include his own daughters. One nobleman, Mastusius, objected, forcing Demiphon to sacrify his daughter. Later, Mastusius killed Demiphon's daughters and tricked the ruler in drinking a cup containing a mixture of their blood and wine. Upon finding out the deed, the king ordered Mastusius and the cup to be thrown into the sea. Crater signifies the cup.[4]

In other cultures

Crater as depicted on The Manuchihr Globe made in Mashhad 1632-33 AD. Adilnor Collection, Sweden.

In

Vermillion Bird of the South (南方朱雀, Nán Fāng Zhū Què).[6] They depict, along with some stars from Hydra, Yi, the Red Bird's wings. Yi also denotes the 27th lunar mansion. Alternatively, Yi depicts a heroic bowman; his bow composed of other stars in Hydra.[7] In the Society Islands, Crater was recognized as a constellation called Moana-'ohu-noa-'ei-ha'a-moe-hara ("vortex-ocean-in-which-to-lose-crime").[8]

Characteristics

Covering 282.4 square degrees and hence 0.685% of the sky, Crater ranks 53rd of the 88 constellations in area.[9] It is bordered by Leo and Virgo to the north, Corvus to the east, Hydra to the south and west, and Sextans to the northwest. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Crt".[10] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930, are defined by a polygon of six segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 10h 51m 14s and 11h 56m 24s, while the declination coordinates are between −6.66° and −25.20°.[11] Its position in the southern celestial hemisphere means that the whole constellation is visible to observers south of 65°N.[9][a]

Features

Stars

Main article: List of stars in Crater
night sky. stars of constellation marked with lines
The constellation Crater as it can be seen by the naked eye.

The German cartographer Johann Bayer used the Greek letters alpha through lambda to label the most prominent stars in the constellation. Bode added more, though only Psi Crateris remains in use. John Flamsteed gave 31 stars in Crater and the segment of Hydra immediately below Crater Flamsteed designations, naming the resulting constellation Hydra et Crater. Most of these stars lie in Hydra.[12] The three brightest stars—Delta, Alpha, and Gamma Crateris—form a triangle located near the brighter star Nu Hydrae in Hydra.[13] Within the constellation's borders, there are 33 stars brighter than or equal to apparent magnitude 6.5.[b][9]

Delta Crateris is the brightest star in Crater at magnitude 3.6. Located 163 ± 4 light-years away,[15] it is an orange giant star of spectral type K0III that is 1.0–1.4 times as massive as the Sun. An ageing star, it has cooled and expanded to 22.44 ± 0.28 times the Sun's radius. It is radiating 171.4 ± 9.0 as much power as the Sun from its outer envelope at an effective temperature of 4,408 ± 57 K.[16] Traditionally called Alkes "the cup",[17][c] and marking the base of the cup is Alpha Crateris,[4] an orange-hued star of magnitude 4.1,[18] that is 141 ± 2 light-years from the Sun.[19] With an estimated mass 1.75 ± 0.24 times that of the Sun, it has exhausted its core hydrogen and expanded to 13.2 ± 0.55 times the Sun's diameter,[20] shining with 69 times its luminosity and an effective temperature of around 4600 K.[21]

With a magnitude of 4.5,

white main sequence star of spectral type A7V, that is an estimated 1.81 times as massive as the Sun,[26] while the secondary—of magnitude 9.6—has 75% the Sun's mass,[26] and is likely an orange dwarf. The two stars take at least 1150 years to orbit each other.[27] The system is 85.6 ± 0.8 light-years away from the Sun.[28]

Ursa Major Moving Group, a collection of stars that share a similar motion through space and may have at one time been members of the same open cluster.[39] The system is located 326 ± 9 light-years from the Sun.[40]

Variable stars are popular targets for amateur astronomers. Their observations provide valuable contributions to understanding star behaviour.

cataclysmic variable; a binary system composed of a white dwarf around as massive as the Sun in close orbit with an orange dwarf of spectral type K5V. The two orbit each other every 6 hours 26 minutes. The white dwarf strips matter off its companion, forming an accretion disk which periodically ignites and erupts. The star system has a magnitude of 15.9 when quiescent, brightening to 12.7 in outburst.[44] SZ Crateris is a magnitude 8.5 BY Draconis type variable star. It is a nearby star system located about 42.9 ± 1.0 light-years from the Sun,[45] and is a member of the Ursa Major Moving Group.[39]

The barred spiral galaxy NGC 3887.[46]

DENIS-P J1058.7-1548 is a brown dwarf less than 5.5% as massive as the Sun. With a surface temperature of between 1700 and 2000 K, it is cool enough for clouds to form. Variations in its brightness in visible and infrared spectra suggest it has some form of atmospheric cloud cover.[48]

BD-10°3166 is a metallic orange main sequence star of spectral type K3.0V, 268 ± 10 light-years distant from the Sun.[52] It was found to have a hot Jupiter-type planet that has a minimum mass of 48% of Jupiter's, and takes only 3.49 days to complete an orbit.[53] WASP-34 is a sun-like star of spectral type G5V that has 1.01 ± 0.07 times the mass and 0.93 ± 0.12 times the diameter of the Sun. It has a planet 0.59 ± 0.01 times as massive as Jupiter that takes 4.317 days to complete an orbit.[54] The system is 432 ± 3 light-years distant from the Sun.[55]

Deep-sky objects

spiral galaxy seen almost edge on
NGC 3981

The

Crater 2 dwarf is a satellite galaxy of the Milky Way,[56] located approximately 380,000 light-years from the Sun.[57] NGC 3511 is a spiral galaxy seen nearly edge-on, of magnitude 11.0, located 2° west of Beta Crateris. Located 11' away is NGC 3513, a barred spiral galaxy.[58] NGC 3981 is a spiral galaxy with two wide and perturbed spiral arms.[59] It is a member of the NGC 4038 Group, which, along with NGC 3672 and NGC 3887, are part of a group of 45 galaxies known as the Crater Cloud within the Virgo Supercluster.[60]

RX J1131 is a quasar located 6 billion light-years away from the Sun. The black hole in the center of the quasar was the first black hole whose spin has ever been directly measured.[61] GRB 011211 was a gamma-ray burst (GRB) detected on December 11, 2001. The burst lasted 270 seconds, making it the longest burst that had ever been detected by X-ray astronomy satellite BeppoSAX up to that point.[62] GRB 030323 lasted 26 seconds and was detected on 23 March 2003.[63]

Meteor showers

The Eta Craterids are a faint meteor shower that takes place between 11 and 22 January, peaking around January 16 and 17, near Eta Crateris.[64]

See also

  • Crater (Chinese astronomy)

Notes

  1. ^ While parts of the constellation technically rise above the horizon to observers between the 65°N and 83°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.[9]
  2. ^ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.[14]
  3. ^ from Arabic الكأس alka's[17]

References

  1. ^ a b "CRT" (PDF). International Astronomical Unions. Archived (PDF) from the original on 6 October 2022. Retrieved 7 December 2022.
  2. Bibcode:1998JBAA..108....9R
    .
  3. Bibcode:1998JBAA..108...79R
    .
  4. ^
    ISBN 978-1609256784
    .
  5. ISBN 978-0-691-17788-5
    .
  6. ^ "AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網" (in Chinese). Taichung, Taiwan: National Museum of Natural Science. 2006. Retrieved 20 February 2017.
  7. ^ Ridpath, Ian. "Corvus and Crater". Star Tales. self-published. Retrieved 6 June 2015.
  8. ^ Henry, Teuira (1907). "Tahitian astronomy". Journal of the Polynesian Society. 16 (2): 101–04.
  9. ^ a b c d Ian Ridpath. "Constellations: Andromeda–Indus". Star Tales. self-published. Retrieved 2 December 2016.
  10. Bibcode:1922PA.....30..469R
    .
  11. ^ "Crater, Constellation Boundary". The Constellations. International Astronomical Union. Retrieved 2 December 2016.
  12. ISBN 978-0-939923-78-6
    .
  13. ^
    ISBN 978-0-7503-0654-6
    .
  14. ^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Retrieved 6 June 2015.
  15. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  16. S2CID 17171848
    .
  17. ^
    ISBN 978-1-931559-44-7
    .
  18. Bibcode:2002yCat.2237....0D
    .
  19. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  20. S2CID 59334290
    . A116.
  21. S2CID 118505114
    . 88.
  22. S2CID 54551449
    .
  23. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  24. S2CID 12232120
    .
  25. ISBN 978-1-4419-6851-7
    .
  26. ^
    S2CID 88503488
    .
  27. ^ Kaler, James B. (Jim) (15 April 2011). "Gamma Crateris". Stars. University of Illinois. Retrieved 5 April 2017.
  28. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
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  29. ISBN 978-1-4614-0830-7
    .
  30. Bibcode:1999MSS...C05....0H
    .
  31. doi:10.1051/0004-6361:20041042-1
    .
  32. ^
    S2CID 118665352. Online data (HIP
    number needed)
  33. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  34. Bibcode:1988mcts.book.....H
    .
  35. S2CID 16673121
    .
  36. S2CID 425754
    .
  37. doi:10.1086/323920
    .
  38. doi:10.1086/300465
    .
  39. ^
    doi:10.1086/368241
    .
  40. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  41. ^ Tooke, Owen. "Variables: What Are They and Why Observe Them?". AAVSO. Retrieved 5 April 2019.
  42. S2CID 125853869
    .
  43. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  44. S2CID 6346887
    .
  45. S2CID 18759600
    .
  46. ^ "A Galactic Traffic Jam". Retrieved 2 March 2020.
  47. S2CID 118912551
    .
  48. S2CID 29406867
    .
  49. S2CID 12042779
    .
  50. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  51. S2CID 59467665
    .
  52. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  53. doi:10.1086/317796
    .
  54. S2CID 43519917
    . A130.
  55. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR
    .
  56. S2CID 119285850
    .
  57. ^ Croswell, Ken (14 April 2016). "Never-before-seen galaxy spotted orbiting the Milky Way". New Scientist. Retrieved 14 April 2016.
  58. ISBN 978-1-4419-1777-5
    .
  59. ^ "A Galactic Gem – ESO's FORS2 instrument captures stunning details of spiral galaxy NGC 3981". European Southern Observatory. 12 September 2018. Retrieved 5 March 2019.
  60. ISSN 0004-637X
    .
  61. ^ "Chandra & XMM-Newton Provide Direct Measurement of Distant Black Hole's Spin". Chandra X-ray Center. 5 March 2014. Retrieved 19 January 2019.
  62. S2CID 4407892. Archived from the original
    (PDF) on 2011-07-18.
  63. S2CID 7963653
    .
  64. ISBN 978-0-521-69691-3
    .

External links

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