Octans
| Constellation | |
 | |
| Abbreviation | Oct[1] |
|---|---|
| Genitive | Octantis |
| Pronunciation | /ˈɒktænz/,genitive/ɒkˈtæntɪs/ |
| Symbolism | theOctant |
| Right ascension | 00hto24h[1] |
| Declination | −74.30° to −90°[1] |
| Quadrant | SQ4 |
| Area | 291 sq. deg. (50th) |
| Main stars | 3 |
| Bayer/Flamsteed stars | 27 |
| Stars withplanets | 3 |
| Stars brighter than 3.00m | 0 |
| Stars within 10.00 pc (32.62 ly) | 1 |
| Brightest star | ν Oct(3.73m) |
| Messier objects | 0 |
| Meteor showers | 0 |
| Bordering constellations | Tucana Indus Pavo Apus Chamaeleon Mensa Hydrus |
| Visible at latitudes between +0° and −90°. Best visible at 21:00 (9 p.m.) during the month ofOctober. Circumpolar | |
Octans(/ˈɒktænz/) is a faintconstellationlocated in the deepSouthern Sky.Its name isLatinfor the eighth part of a circle, but it is named after theoctant,anavigational instrument.Devised byFrenchastronomerNicolas Louis de Lacaillein 1752, Octans remains one of the88 modern constellations.The southerncelestial poleis located within the boundaries of Octans.
History and mythology[edit]
Octans was one of 14 constellations created by French astronomerNicolas Louis de Lacailleduring his expedition to theCape of Good Hope,and was originally namedl’Octans de Reflexion( “the reflecting octant” ) in 1752, after he had observed and catalogued almost 10,000 southern stars during a two-year stay at theCape of Good Hope.He devised fourteen new constellations in uncharted regions of theSouthern Celestial Hemispherenot visible from Europe. All but one honoured instruments that symbolised theAge of Enlightenment.[a][2]
It was part of his catalogue of the southern sky, theCoelum Australe Stelliferum,which was published posthumously in 1763. In Europe, it became more widely known asOctans Hadleianus,in honor ofEnglishmathematicianJohn Hadley,who invented the octant in 1730. There is no real mythology related to Octans, partially due to its faintness and relative recentness, but mostly because of its extreme southerly latitude.[3]
Notable features[edit]
Stars[edit]
Octans is a generally inconspicuous constellation with only one star brighter than magnitude 4; its brightest member isNu Octantis,aspectral classK1 IIIgiant starwith anapparent magnitude3.73. It is 63.3 ± 0.8light-yearsdistant from Earth.[4]
Beta Octantisis the second brightest star in the constellation.
Polaris Australis (Sigma Octantis),the southernpole star,is a magnitude 5.4 star just over 1 degree away from the true south celestial pole. Its relative faintness means that it is not practical for navigation.[5]
BQ Octantisis a fainter, magnitude 6.82 star located much closer to the South Pole (at less than a degree) than Sigma.
In addition to having the current southern pole star of Earth, Octans also contains the southern pole star of the planetSaturn,which is the magnitude 4.3Delta Octantis.
TheAstronomical Society of Southern Africain 2003 reported that observations of theMira variablestarsRandT Octantiswere urgently needed.[6]
Three star systems are known to have planets.Mu2Octantisis a binary star system, the brighter component of which has a planet.Nu OctantisA also has a planet orbiting.HD 142022is a binary system, a component of which is a sunlike star with a massive planet with an orbital period of 1928 ± 46 days.HD 212301is a yellow-white main sequence star with ahot jupiterthat completes an orbit every 2.2 days.
Deep sky objects[edit]
NGC 2573(also known as Polarissima Australis) is a faintbarred spiral galaxythat happens to be the closestNGC objectto thesouth celestial pole.NGC 7095andNGC 7098are two barred spiral galaxies that are 115 million and 95 million light-years distant from Earth respectively. The sparseopen clusterCollinder 411is also located in the constellation.
Namesakes[edit]
USSOctans(AF-26)was astores shipused by theUnited States NavyduringWorld War II.
See also[edit]
Notes[edit]
- ^The exception isMensa,named for theTable Mountain.The other thirteen (alongside Horologium) areAntlia,Caelum,Circinus,Fornax,Horologium,Microscopium,Norma,Pictor,Pyxis,Reticulum,SculptorandTelescopium.[2]
References[edit]
- Citations
- ^abc"Octans, Constellation Boundary".The Constellations.International Astronomical Union.Retrieved10 Mar2023.
- ^abWagman, Morton (2003).Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others.Blacksburg, Virginia: The McDonald & Woodward Publishing Company. pp. 6–7.ISBN978-0-939923-78-6.
- ^Staal 1988,p. 257.
- ^Brown, A. G. A.;et al. (Gaia collaboration) (August 2018)."GaiaData Release 2: Summary of the contents and survey properties ".Astronomy & Astrophysics.616.A1.arXiv:1804.09365.Bibcode:2018A&A...616A...1G.doi:10.1051/0004-6361/201833051.Gaia DR2 record for this sourceatVizieR.
- ^Staal 1988,p. 258.
- ^Cooper, Tim (2003). "Presidential address: Amateur Observations – Successes and Opportunities".Monthly Notes of the Astronomical Society of Southern Africa.62:234–240.Bibcode:2003MNSSA..62..234C.
- References
- Ridpath, Ian; Tirion, Wil (2017),Stars and Planets Guide,Princeton University Press,ISBN978-0-691-17788-5
- Staal, Julius D.W. (1988),The New Patterns in the Sky: Myths and Legends of the Stars,The McDonald and Woodward Publishing Company,ISBN0-939923-04-1
External links[edit]
- The Deep Photographic Guide to the Constellations: Octans
- The clickable Octans
- Starry Night Photography: Octans
- Star Tales – Octans
