Apus

For the high school college credit course, see Advanced Placement United States History. For other uses, see Apus (disambiguation).
Apus
Constellation

Abbreviation Aps
Genitive Apodis
Pronunciation /ˈeɪpəs/, genitive /ˈæpədᵻs/
Symbolism The Bird-of-Paradise[1]
Right ascension 13h 51m 07.5441s–18h 27m 27.8395s[2]
Declination −67.4800797°–−83.1200714°[2]
Family Bayer
Area 206 sq. deg. (67th)
Main stars 4
Bayer/Flamsteed
stars		 12
Stars with planets 3
Stars brighter than 3.00m 0
Stars within 10.00 pc (32.62 ly) 0
Brightest star α Aps (3.83m)
Nearest star HD 128400
(66.36 ly, 20.35 pc)
Messier objects None
Meteor showers None
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 constellation in the southern sky, first defined in the late 16th century. Its name means "no feet" in Greek, and it represents a bird-of-paradise, which was once wrongly believed to lack feet. Its genitive is "Apodis". The orange giant Alpha Apodis is the brightest star in the constellation. Three star systems have been found to have planets.

History

Apus was one of twelve constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman. It first appeared on a 35 cm diameter celestial globe published in 1597 or 1598 in Amsterdam by Plancius with Jodocus Hondius.[1][3][4] Plancius called the constellation Paradysvogel Apis Indica; the first word is Dutch for "bird of paradise", of genus Pteridophora, but the others are Latin for "Indian Bee". Apis (Latin for "bee") is presumably an error for avis ("bird").[1][4]

The name Apus is derived from the Greek apous, meaning "without feet". This referred to the Western misconception that the bird-of-paradise had no feet, which arose because the only specimens available in the West had their feet and wings removed.[1] Such specimens began to arrive in Europe in 1522, when the survivors of Ferdinand Magellan's expedition brought them home.[5]

After its introduction on Plancius's globe, the constellation's first known appearance in a celestial atlas was in Johann Bayer's Uranometria of 1603, where it was called "Apis Indica".[1][4]

Richard Allen reports Semler's assertion that de Houtman, who observed the southern constellations from the island of Sumatra, took his ideas for the formation of Apus (as well as Phoenix and Indus) from the Chinese, who knew the stars of Apus as the "Little Wonder Bird",[6] and that Semler's assertion was disputed by Ideler (though Ideler acknowledged the Chinese constellations).

Characteristics

Covering 206.3 square degrees and hence 0.500% of the sky, Apus ranks 67th of the 88 modern constellations by area.[7] Its position in the Southern Celestial Hemisphere means that the whole constellation is visible to observers south of 7°N.[7][lower-alpha 1] 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'.[8] The official constellation boundaries, as set by 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 13h 49.5m and 18h 27.3m, while the declination coordinates are between -67.48° and -83.12°.[2]

Notable features

The constellation Apus as it can be seen by the naked eye.

Stars

Within the constellation's borders, there are 39 stars brighter than or equal to apparent magnitude 6.5.[lower-alpha 2][7]

Alpha Apodis is an orange giant of spectral type K3III 447 ± 8 light years away from Earth,[10] with a magnitude of 3.8.[3][4] It spent much of its life as a blue-white (B-type) main sequence star before expanding, cooling and brightening as it used up its core hydrogen,[11] now shining with a luminosity approximately 928 times that of the Sun, with a surface temperature of 4312 K.[12] Beta Apodis is an orange giant 157 ± 2 light years away,[10] with a magnitude of 4.2.[3] It is around 1.84 times as massive as the Sun, with a surface temperature of 4677 K.[13] Gamma Apodis is an yellow giant of spectral type G8III located 156 ± 1 light-years away,[10] with a magnitude of 3.87. It is approximately 63 times as luminous the Sun, with a surface temperature of 5279 K.[12] Delta Apodis is a double star with a separation of 103 arcseconds.[4] Delta1 is a red giant star of spectral type M4III located 760 ± 30 light years away.[10] It is a semiregular variable that varies from magnitude +4.66 to +4.87,[14] with pulsations of multiple periods of 68.0, 94.9 and 101.7 days.[15] Delta2 is an orange giant star[4] located 610 ± 30 light years away,[10] with a magnitude of 5.3. The separate components can be resolved with binoculars, a telescope, or the naked eye.[3] Theta Apodis is a variable red giant at a distance of 328 light years with a period of approximately 4 months,[3] or 109 days.[4] It has a maximum magnitude of 4.8 and a minimum magnitude of 6.1.[4]

NO Apodis is a red giant of spectral type M3III that varies between magnitudes 5.71 and 5.95.[16] Located around 883 light-years distant, it shines with a luminosity approximately 2059 times that of the Sun and has a surface temperature of 3568 K.[12]

S Apodis is a rare R Coronae Borealis variable, an extremely hydrogen-deficient supergiant thought to have arisen as the result of the merger of two white dwarfs; fewer than 100 have been discovered as of 2012. It has a baseline magnitude of 9.7.[17]

Deep-sky objects

The most prominent deep-sky objects in Apus include the globular clusters NGC 6101 and IC 4499 as well as the spiral galaxy IC 4633.

Globular cluster IC 4499 taken by Hubble Space Telescope.[18]

Equivalents

When the Ming Dynasty Chinese astronomer Xu Guangqi adapted the European southern hemisphere constellations to the Chinese system in The Southern Asterisms, he combined Apus with some of the stars in Octans to form the "Exotic Bird" (異雀, Yìquè).[21]

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.[7]
  2. ↑ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.[9]

References

Citations
  1. 1 2 3 4 5 Ridpath, Ian. "Apus". Star Tales. Retrieved 10 April 2012.
  2. 1 2 3 "Apus, constellation boundary". The Constellations (International Astronomical Union). Retrieved 14 February 2014.
  3. 1 2 3 4 5 Ridpath 2001, pp. 76-77.
  4. 1 2 3 4 5 6 7 8 9 10 Plotner, Tammy (13 October 2008). "Apus". Universe Today. Retrieved 22 April 2012.
  5. ↑ Staal 1988, p. 252.
  6. ↑ Richard H. Allen (1899) Star Names: Their Lore and Meaning, p. 45 <http://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Apus*.html>
  7. 1 2 3 4 Ridpath, Ian. "Constellations: Andromeda–Indus". Star Tales. self-published. Retrieved 26 August 2015.
  8. ↑ Russell, Henry Norris (1922). "The New International Symbols for the Constellations". Popular Astronomy 30: 469. Bibcode:1922PA.....30..469R.
  9. ↑ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Retrieved 26 August 2015.
  10. 1 2 3 4 5 van Leeuwen, F. (2007). "Validation of the New Hipparcos Reduction". Astronomy and Astrophysics 474 (2): 653–64. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357.
  11. ↑ Kaler, James B. (6 April 2007). "Alpha Aps". Stars. University of Illinois. Retrieved 30 March 2016.
  12. 1 2 3 McDonald, I.; Zijlstra, A. A.; Boyer, M. L. (2012). "Fundamental Parameters and Infrared Excesses of Hipparcos Stars". Monthly Notices of the Royal Astronomical Society 427 (1): 343–57. arXiv:1208.2037. Bibcode:2012MNRAS.427..343M. doi:10.1111/j.1365-2966.2012.21873.x.
  13. ↑ Liu, Y. J.; Zhao, G.; Shi, J. R.; Pietrzyński, G.; Gieren, W. (2007). "The abundances of nearby red clump giants". Monthly Notices of the Royal Astronomical Society 382 (2): 553–66. Bibcode:2007MNRAS.382..553L. doi:10.1111/j.1365-2966.2007.11852.x.
  14. ↑ Watson, Christopher (25 August 2009). "Delta1 Apodis". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 30 March 2016.
  15. ↑ Tabur, V.; Bedding, T.R.; Kiss, L.L.; Moon, T.T.; Szeidl, B.; Kjeldsen, H. (2009). "Long-term photometry and periods for 261 nearby pulsating M giants". Monthly Notices of the Royal Astronomical Society 400 (4): 1945–61. arXiv:0908.3228. Bibcode:2009MNRAS.400.1945T. doi:10.1111/j.1365-2966.2009.15588.x.
  16. ↑ Watson, Christopher (25 August 2009). "NO Apodis". The International Variable Star Index. American Association of Variable Star Observers. Retrieved 31 March 2015.
  17. ↑ Tisserand; Clayton; Welch; Pilecki; Wyrzykowski; Kilkenny (2012). "The Ongoing Pursuit of R Coronae Borealis Stars: ASAS-3 Survey Strikes Again". Astronomy & Astrophysics 551: 22. arXiv:1211.2475. Bibcode:2013A&A...551A..77T. doi:10.1051/0004-6361/201220713. A77.
  18. ↑ "IC 4499: A globular cluster’s age revisited". ESA/Hubble Picture of the Week. Retrieved 5 August 2014.
  19. 1 2 Ferraro, I.; Ferraro, F.R.; Pecci, F. Fusi; Corsi, C.E.; Buonanno, R. (August 1995). "Young globular clusters in the Milky Way: IC 4499". Monthly Notices of the Royal Astronomical Society (SAO/NASA ADS Astronomy Abstract Service) 275 (4): 1057–1076. Bibcode:1995MNRAS.275.1057F. doi:10.1093/mnras/275.4.1057. Retrieved 22 April 2012.
  20. ↑ Frommert, Hartmut. "IC 4499". Students for the Exploration and Development of Space. Retrieved 22 April 2012.
  21. ↑ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日
References

External links

Wikimedia Commons has media related to Apus.

Coordinates: 16h 00m 00s, −75° 00′ 00″

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