Apus

Coordinates: Sky map 16h 00m 00s, −75° 00′ 00″
Source: Wikipedia, the free encyclopedia.
For other uses, see Apus (disambiguation).

Apus
Constellation
67th)
Main stars4
Bayer/Flamsteed
stars		12
Stars with planets2
Stars brighter than 3.00m0
Stars within 10.00 pc (32.62 ly)0
Brightest starα Aps (3.83m)
Messier objects0
Meteor showers0
Bordering
constellations		Triangulum Australe
Circinus
Musca
Chamaeleon
Octans
Pavo
Ara
Visible at latitudes between +5° and −90°.
Best visible at 21:00 (9 p.m.) during the month of July.

Apus is a small

Nicolas Louis de Lacaille charted and gave the brighter stars their Bayer designations
in 1756.

The five brightest stars are all reddish in hue. Shading the others at apparent magnitude 3.8 is Alpha Apodis, an orange giant that has around 48 times the diameter and 928 times the luminosity of the Sun. Marginally fainter is Gamma Apodis, another aging giant star. Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible with the naked eye. Two star systems have been found to have planets.

History

A black line drawing on faded brownish paper depicting a stylized bird with no feet and a triangle superimposed on some stars
Detail of Johann Bayer's 1603 Uranometria, showing the constellations Apus, Chamaeleon, Musca (as "Apis", the Bee), and Triangulum Australe, as well as the South celestial pole.

Apus was one of twelve constellations published by

Eerste Schipvaart, to the East Indies. It first appeared on a 35-cm (14 in) diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius.[4] De Houtman included it in his southern star catalogue in 1603 under the Dutch name De Paradijs Voghel, "The Bird of Paradise",[5][6] and Plancius called the constellation Paradysvogel Apis Indica; the first word is Dutch for "bird of paradise". Apis (Latin for "bee") is assumed to have been a typographical error for avis ("bird").[5][2]

After its introduction on Plancius's globe, the constellation's first known appearance in a celestial atlas was in German cartographer

expedition brought them home.[2] The constellation later lost some of its tail when Nicolas-Louis de Lacaille used those stars to establish Octans in the 1750s.[2]

Characteristics

Covering 206.3 square degrees and hence 0.5002% of the sky, Apus ranks 67th of the

Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 7°N.[8][a] It is bordered by Ara, Triangulum Australe and Circinus to the north, Musca and Chamaeleon to the west, Octans to the south, and Pavo to the east. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Aps".[9] The official constellation boundaries, as set by Belgian astronomer Eugène Delporte in 1930,[b] 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 13h 49.5m and 18h 27.3m , while the declination coordinates are between −67.48° and −83.12°.[3]

Features

Stars

See also: List of stars in Apus

Lacaille gave twelve stars Bayer designations, labelling them Alpha through to Kappa, including two stars next to each other as Delta and another two stars near each other as Kappa.[7] Within the constellation's borders, there are 39 stars brighter than or equal to apparent magnitude 6.5.[c][8] Beta, Gamma and Delta Apodis form a narrow triangle, with Alpha Apodis lying to the east.[12] The five brightest stars are all red-tinged, which is unusual among constellations.[13]

Alpha Apodis is an

orange giant star of spectral type K3III,[23] located 550 ± 10 light-years away,[14] with a magnitude of 5.3. The separate components can be resolved with the naked eye.[15]

The fifth-brightest star is Zeta Apodis at magnitude 4.8,[13] a star that has swollen and cooled to become an orange giant of spectral type K1III, with a surface temperature of 4649 K and a luminosity 133 times that of the Sun.[18] It is 300 ± 4 light-years distant.[14] Near Zeta is Iota Apodis, a binary star system 1,040 ± 60 light-years distant,[14] that is composed of two blue-white main sequence stars that orbit each other every 59.32 years. Of spectral types B9V and B9.5 V, they are both over three times as massive as the Sun.[24]

Eta Apodis is a white main sequence star located 140.8 ± 0.9 light-years distant.[14] Of apparent magnitude 4.89, it is 1.77 times as massive, 15.5 times as luminous as the Sun and has 2.13 times its radius. Aged 250 ± 200 million years old, this star is emitting an excess of 24 μm infrared radiation, which may be caused by a debris disk of dust orbiting at a distance of more than 31 astronomical units from it.[25]

variable star designation, yet has turned out not to be variable. Of magnitude 5.3,[13]
it is another orange giant.

Two star systems have had exoplanets discovered by doppler spectroscopy, and the substellar companion of a third star system—the sunlike star HD 131664—has since been found to be a brown dwarf with a calculated mass of the companion to 23 times that of Jupiter (minimum of 18 and maximum of 49 Jovian masses).[30] HD 134606 is a yellow sunlike star of spectral type G6IV that has begun expanding and cooling off the main sequence.[31] Three planets orbit it with periods of 12, 59.5 and 459 days, successively larger as they are further away from the star.[32] HD 137388 is another star—of spectral type K2IV—that is cooler than the Sun and has begun cooling off the main sequence.[31] Around 47% as luminous and 88% as massive as the Sun, with 85% of its diameter, it is thought to be around 7.4 ± 3.9 billion years old.[33] It has a planet that is 79 times as massive as the Earth and orbits its sun every 330 days at an average distance of 0.89 astronomical units (AU).[34]

Deep-sky objects

A spherical shaped group of a multitude of stars
Globular cluster IC 4499 taken by Hubble Space Telescope.[35]

The Milky Way covers much of the constellation's area.[36] Of the deep-sky objects in Apus, there are two prominent globular clusters—NGC 6101 and IC 4499—and a large faint nebula that covers several degrees east of Beta and Gamma Apodis.[37] NGC 6101 is a globular cluster of apparent magnitude 9.2 located around 50,000 light-years distant from Earth,[38] which is around 160 light-years across. Around 13 billion years old, it contains a high concentration of massive bright stars known as blue stragglers, thought to be the result of two stars merging.[39] IC 4499 is a loose globular cluster in the medium-far galactic halo;[40] its apparent magnitude is 10.6.[41]

The galaxies in the constellation are faint.

integrated flux nebulae—large faint clouds thought to be lit by large numbers of stars.[38]

See also

Notes

  1. ^ While parts of the constellation technically rise above the horizon to observers between the 7°N and 22°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.[8]
  2. ^ Delporte had proposed standardising the constellation boundaries to the International Astronomical Union, who had agreed and gave him the lead role.[10]
  3. ^ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.[11]

References

  1. ^ Entry in Oxford English Dictionary, (OED Third Edition, November 2010).
  2. ^ a b c d Ridpath, Ian. "Apus". Star Tales. Retrieved 10 April 2012.
  3. ^ a b c "Apus, constellation boundary". The Constellations. International Astronomical Union. Retrieved 14 February 2014.
  4. ^ a b Ridpath, Ian. "Johann Bayer's Southern Star Chart". Star Tales. self-published. Retrieved 30 May 2016.
  5. ^ a b Ley, Willy (December 1963). "The Names of the Constellations". For Your Information. Galaxy Science Fiction. pp. 90–99.
  6. ^ Ridpath, Ian. "Frederick de Houtman's Catalogue". Star Tales. self-published. Retrieved 30 May 2016.
  7. ^
    ISBN 978-0-939923-78-6
    .
  8. ^ a b c d Ridpath, Ian. "Constellations: Andromeda–Indus". Star Tales. self-published. Retrieved 26 August 2015.
  9. Bibcode:1922PA.....30..469R
    .
  10. ^ Ridpath, Ian. "Constellation boundaries: How the modern constellation outlines came to be". Star Tales. self-published. Retrieved 1 June 2016.
  11. ^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Archived from the original on 31 March 2014. Retrieved 26 August 2015.
  12. ISBN 978-1-4481-2691-0
    .
  13. ^
    ISBN 978-0-7503-0654-6
    .
  14. ^
    doi:10.1051/0004-6361/201833051
    .
  15. ^
    ISBN 978-0-691-17788-5
    .
  16. ^ Kaler, James B. (6 April 2007). "Alpha Aps". Stars. University of Illinois. Retrieved 30 March 2016.
  17. S2CID 425754
    .
  18. ^
    S2CID 118665352
    .
  19. doi:10.1111/j.1365-2966.2007.11852.x
    .
  20. ISBN 978-1-4614-7648-1
    .
  21. ^ Watson, Christopher (25 August 2009). "Delta1 Apodis". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 30 March 2016.
  22. S2CID 15358380
    .
  23. Bibcode:1975mcts.book.....H
    .
  24. doi:10.1093/mnras/sts045
    .
  25. S2CID 51417657
    .
  26. doi:10.1111/j.1365-2966.2004.08344.x
    .
  27. S2CID 56041336
    . See table 1, IRAS 14003-7633.
  28. ^ Watson, Christopher (25 August 2009). "NO Apodis". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 31 March 2015.
  29. S2CID 59060842
    . A77.
  30. S2CID 54986291
    .
  31. ^
    S2CID 119476992
    .
  32. S2CID 8130257
    . 91.
  33. S2CID 54555839
    .
  34. S2CID 119192207. Archived from the original
    on 2015-05-29. Retrieved 2016-05-29.
  35. ^ "IC 4499: A globular cluster's age revisited". ESA/Hubble Picture of the Week. Retrieved 5 August 2014.
  36. ISBN 978-1-85233-709-4
    .
  37. ^
    ISBN 978-0-522-87124-1
    .
  38. ^
    ISBN 978-1-4614-4750-4
    .
  39. ISBN 978-0-521-82796-6
    .
  40. doi:10.1093/mnras/275.4.1057
    .
  41. ^ Frommert, Hartmut. "IC 4499". Students for the Exploration and Development of Space. Retrieved 22 April 2012.

External links

Wikimedia Commons has media related to Apus (constellation).


Retrieved from "https://en.wikipedia.org/w/index.php?title=Apus&oldid=1204876992"
This page is based on the copyrighted Wikipedia article: Apus. Articles is available under the CC BY-SA 3.0 license; additional terms may apply.Privacy Policy