View source for Astronomy:Apus

{{Short description|Constellation in the southern celestial hemisphere}}

{{Infobox constellation
| name = Apus
| abbreviation = Aps
| genitive = Apodis
| pronounce = {{IPAc-en|ˈ|eɪ|p|ə|s}}, genitive {{IPAc-en|UK|ˈ|eɪ|p|ə|,_|'|æ|p|ə|,|ə|'|p|oʊ|-|d|ᵻ|s}}, genitive {{IPAc-en|US|ˈ|eɪ|p|ə|,_|'|æ|p|ə|,|ə|'|p|oʊ|-|d|ə|s}}<ref>[https://www.oed.com/view/Entry/249206?redirectedFrom=Apus#eid Entry] in Oxford English Dictionary, (OED Third Edition, November 2010).</ref>
| symbolism = The [[Biology:Bird-of-paradise|Bird-of-Paradise]]<ref name="ridpath"/>
| RA = {{RA|13|51|07.5441}} – {{RA|18|27|27.8395}}<ref name=boundary>{{Cite journal | title=Apus, constellation boundary | journal=The Constellations | publisher=International Astronomical Union |url=https://www.iau.org/public/themes/constellations/#aps | access-date=14 February 2014 }}</ref>
| dec= {{dec|-67.4800797}} to {{dec|-83.1200714}}<ref name=boundary/>
| family = Bayer
| areatotal = 206
| arearank = 67th
| numbermainstars = 4
| numberbfstars = 12
| numberstarsplanets = 2
| numberbrightstars = 0
| numbernearbystars = 0
| brighteststarname = [[Astronomy:Alpha Apodis|α Aps]]
| starmagnitude = 3.83
| meteorshowers = 0
| numbermessierobjects = 0
| bordering = [[Astronomy:Triangulum Australe|Triangulum Australe]]<br />[[Astronomy:Circinus|Circinus]]<br />[[Astronomy:Musca|Musca]]<br />[[Astronomy:Chamaeleon|Chamaeleon]]<br />[[Astronomy:Octans|Octans]]<br />[[Astronomy:Pavo (constellation)|Pavo]]<br />[[Astronomy:Ara (constellation)|Ara]]
| latmax = 5
| latmin = [[Earth:South Pole|90]]
| month = July
| notes =
}}

'''Apus''' is a small [[Astronomy:Constellation|constellation]] in the southern sky. It represents a [[Biology:Bird-of-paradise|bird-of-paradise]], and its name means "without feet" in [[Social:Greek language|Greek]] because the bird-of-paradise was once wrongly believed to lack feet. First depicted on a celestial globe by [[Biography:Petrus Plancius|Petrus Plancius]] in 1598, it was charted on a star atlas by Johann Bayer in his 1603 ''[[Astronomy:Uranometria|Uranometria]]''. The French explorer and astronomer Nicolas Louis de Lacaille charted and gave the brighter stars their [[Astronomy:Bayer designation|Bayer designation]]s in 1756.

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

==History==

[[File:BayerUran1661apuschamtri.jpg|thumb|left|upright|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.|alt=A black line drawing on faded brownish paper depicting a stylized bird with no feet and a triangle superimposed on some stars]]

Apus was one of twelve constellations published by [[Biography:Petrus Plancius|Petrus Plancius]] from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman who had sailed on the first Dutch trading expedition, known as the ''Eerste Schipvaart'', to the [[Place:East Indies|East Indies]]. It first appeared on a 35-cm (14&nbsp;in) diameter celestial globe published in 1598 in Amsterdam by Plancius with Jodocus Hondius.<ref name=ridpathbayer>{{cite web| url=http://www.ianridpath.com/startales/bayer-southern.html | title=Johann Bayer's Southern Star Chart|last1=Ridpath|first1=Ian|publisher=self-published |work=Star Tales | access-date= 30 May 2016}}</ref><!-- cites previous 2 sentences --> De Houtman included it in his southern star catalogue in 1603 under the Dutch name ''De Paradijs Voghel'', "The Bird of Paradise",<ref name="ley196312">{{Cite magazine
 |last=Ley
 |first=Willy
 |date=December 1963
 |title=The Names of the Constellations
 |department=For Your Information
 |url=https://archive.org/stream/Galaxy_v22n02_1963-12#page/n46/mode/1up
 |magazine=Galaxy Science Fiction
 |pages=90–99
}}</ref><ref>{{cite web| url=http://www.ianridpath.com/startales/startales1c.html#houtman | title=Frederick de Houtman's Catalogue|last1=Ridpath|first1=Ian|publisher=self-published |work=Star Tales | access-date= 30 May 2016}}</ref> and Plancius called the constellation ''Paradysvogel Apis Indica''; the first word is [[Social:Dutch language|Dutch]] for "bird of paradise". ''Apis'' (Latin for "bee") is assumed to have been a typographical error for ''avis'' ("bird").{{r|ley196312}}<ref name="ridpath">{{cite web |url = http://www.ianridpath.com/startales/apus.htm |title = Apus |last = Ridpath |first = Ian |work = Star Tales |access-date = 10 April 2012}}</ref>

After its introduction on Plancius's globe, the constellation's first known appearance in a celestial atlas was in German cartographer Johann Bayer's ''[[Astronomy:Uranometria|Uranometria]]'' of 1603.<ref name=ridpathbayer/> Bayer called it ''Apis Indica'' while fellow astronomers [[Biography:Johannes Kepler|Johannes Kepler]] and his son-in-law Jakob Bartsch called it ''Apus'' or ''Avis Indica''.<ref name=wagman>{{cite book| last = Wagman |first = Morton| date = 2003| title = Lost Stars: Lost, Missing and Troublesome Stars from the Catalogues of Johannes Bayer, Nicholas Louis de Lacaille, John Flamsteed, and Sundry Others| publisher = The McDonald & Woodward Publishing Company| location = Blacksburg, Virginia| isbn = 978-0-939923-78-6 |pages=30–32}}</ref> 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. Such specimens began to arrive in Europe in 1522, when the survivors of Ferdinand Magellan's expedition brought them home.<ref name="ridpath"/><!-- cites previous two sentences --> The constellation later lost some of its tail when Nicolas-Louis de Lacaille used those stars to establish [[Astronomy:Octans|Octans]] in the 1750s.<ref name="ridpath"/><!-- cites previous 1.5 sentences -->

==Characteristics==
Covering 206.3 square degrees and hence 0.5002% of the sky, Apus ranks 67th of the [[Astronomy:88 modern constellations|88 modern constellations]] by area.<ref name=tirionconst>{{cite web| url=http://www.ianridpath.com/constellations1.html | title=Constellations: Andromeda–Indus | work= Star Tales |author=Ridpath, Ian |publisher=self-published | access-date= 26 August 2015}}</ref> Its position in the Southern Celestial Hemisphere means that the whole [[Astronomy:Constellation|constellation]] is visible to observers south of 7°N.<ref name=tirionconst/>{{efn|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.<ref name=tirionconst/>}} It is bordered by [[Astronomy:Ara (constellation)|Ara]], [[Astronomy:Triangulum Australe|Triangulum Australe]] and [[Astronomy:Circinus|Circinus]] to the north, [[Astronomy:Musca|Musca]] and [[Astronomy:Chamaeleon|Chamaeleon]] to the west, Octans to the south, and [[Astronomy:Pavo (constellation)|Pavo]] to the east. The three-letter abbreviation for the constellation, as adopted by the [[Organization:International Astronomical Union|International Astronomical Union]] in 1922, is "Aps".<ref name="pa30_469">{{cite journal | last=Russell | first=Henry Norris |author-link=Henry Norris Russell | title=The New International Symbols for the Constellations | journal=Popular Astronomy | volume=30 | page=469 | bibcode=1922PA.....30..469R | date=1922 }}</ref> The official constellation boundaries, as set by Belgian astronomer [[Biography:Eugène Joseph Delporte|Eugène Delporte]] in 1930,{{efn|1=Delporte had proposed standardising the constellation boundaries to the International Astronomical Union, who had agreed and gave him the lead role.<ref name=tirionconstbnd>{{cite web| url=http://www.ianridpath.com/boundaries.html | title=Constellation boundaries: How the modern constellation outlines came to be| work= Star Tales |author=Ridpath, Ian |author-link=Ian Ridpath|publisher=self-published | access-date= 1 June 2016}}</ref>}} are defined by a polygon of six segments (''illustrated in infobox''). In the [[Astronomy:Equatorial coordinate system|equatorial coordinate system]], the [[Right ascension|right ascension]] coordinates of these borders lie between {{RA|13|49.5}} and {{RA|18|27.3}}, while the [[Declination|declination]] coordinates are between −67.48° and −83.12°.<ref name="boundary" />

==Features==
===Stars===
Lacaille gave twelve stars [[Astronomy:Bayer designation|Bayer designation]]s, labelling them Alpha through to Kappa, including two stars next to each other as Delta and another two stars near each other as Kappa.<ref name=wagman/> Within the constellation's borders, there are 39 stars brighter than or equal to [[Astronomy:Apparent magnitude|apparent magnitude]]&nbsp;6.5.{{efn|1=Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.<ref>{{cite web|url=http://www.skyandtelescope.com/resources/darksky/3304011.html?page=1&c=y|title=The Bortle Dark-Sky Scale|last=Bortle|first=John E.|date=February 2001|work=Sky & Telescope|access-date=26 August 2015}}</ref>}}<ref name=tirionconst/> [[Astronomy:Beta Apodis|Beta]], [[Astronomy:Gamma Apodis|Gamma]] and [[Astronomy:Delta Apodis|Delta Apodis]] form a narrow triangle, with [[Astronomy:Alpha Apodis|Alpha Apodis]] lying to the east.<ref>{{cite book |last=Thompson |first=Mark |title=A Down to Earth Guide to the Cosmos |publisher=Random House |date=2013 | location=New York, New York |isbn=978-1-4481-2691-0 |url=https://books.google.com/books?id=SOfRFJBy-igC&pg=PT161}}</ref> The five brightest stars are all red-tinged, which is unusual among constellations.<ref name=arnold>{{cite book |author1=Arnold, H.J.P |author2=Doherty, Paul |author3=Moore, Patrick |title=The Photographic Atlas of the Stars |publisher=CRC Press |location=Boca Raton, Florida |date=1999 |page=144 |isbn=978-0-7503-0654-6 |url=https://books.google.com/books?id=YjcvJUfnWBAC&pg=PA144}}</ref>

Alpha Apodis is an [[Astronomy:Giant star|orange giant]] of spectral type K3III located 430 ± 20 [[Astronomy:Light-year|light-year]]s away from Earth,<ref name=dr2>{{cite DR2}}</ref> with an apparent magnitude of 3.8.<ref name=ridpath01>{{cite book |last = Ridpath |first = Ian |date = 2017 |title = Stars and Planets Guide |publisher = Princeton University Press |location=Princeton, New Jersey |isbn = 978-0-691-17788-5 |pages=78–79}}</ref> It spent much of its life as a [[Astronomy:B-type main-sequence star|blue-white (B-type) main sequence star]] before expanding, cooling and brightening as it used up its core hydrogen.<ref name=kaler>{{cite web | title=Alpha Aps | work=Stars | first=James B. | last=Kaler | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/alphaaps.html | date=6 April 2007 | access-date=30 March 2016}}</ref> It has swollen to 48 times the Sun's diameter,<ref name=aaa367_521>{{cite journal | last1=Pasinetti Fracassini | first1=L. E. | last2=Pastori | first2=L. | last3=Covino | first3=S. | last4=Pozzi | first4=A. | title=Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics | journal=Astronomy and Astrophysics | volume=367 | issue=2 | pages=521–524 | date=2001 | doi=10.1051/0004-6361:20000451 | bibcode=2001A&A...367..521P | arxiv=astro-ph/0012289| s2cid=425754 }}</ref> and shines with a [[Astronomy:Luminosity|luminosity]] approximately 928 times that of the Sun, with a surface temperature of 4312 [[Kelvin|K]].<ref name=Mcdonald>{{cite journal|author=McDonald, I.|author2=Zijlstra, A. A.|author3=Boyer, M. L.|date=2012|title=Fundamental Parameters and Infrared Excesses of Hipparcos Stars|journal=Monthly Notices of the Royal Astronomical Society|volume=427|issue=1|pages=343–57|bibcode=2012MNRAS.427..343M|arxiv = 1208.2037 |doi = 10.1111/j.1365-2966.2012.21873.x |s2cid=118665352}}</ref> Beta Apodis is an orange giant 149 ± 2 light-years away,<ref name=dr2/> with a magnitude of 4.2.<ref name=ridpath01/> It is around 1.84 times as massive as the Sun, with a surface temperature of 4677 K.<ref>{{cite journal|author=Liu, Y. J.|author2=Zhao, G.|author3=Shi, J. R.|author4=Pietrzyński, G.|author5=Gieren, W.|date=2007|title=The abundances of nearby red clump giants|journal=Monthly Notices of the Royal Astronomical Society|volume=382|issue=2|pages=553–66|bibcode=2007MNRAS.382..553L |doi=10.1111/j.1365-2966.2007.11852.x|doi-access=free}}</ref> Gamma Apodis is a [[Astronomy:Giant star|yellow giant]] of spectral type G8III located 150 ± 4 light-years away,<ref name=dr2/> with a magnitude of 3.87. It is approximately 63 times as luminous the Sun, with a surface temperature of 5279 K.<ref name=Mcdonald/> Delta Apodis is a [[Astronomy:Double star|double star]], the two components of which are 103 arcseconds apart and visible through binoculars.<ref>{{cite book |last1=Privett |first1=Grant |last2=Jones |first2=Kevin |title=The Constellation Observing Atlas |publisher=Springer Science & Business Media |location=New York, New York |date=2013 |page=13 |isbn=978-1-4614-7648-1 |url=https://books.google.com/books?id=uN69BAAAQBAJ&pg=PA13}}</ref> Delta<sup>1</sup> is a [[Astronomy:Red giant|red giant]] star of spectral type M4III located 630 ± 30 light-years away.<ref name=dr2/> It is a semiregular variable that varies from magnitude +4.66 to +4.87,<ref name=AAVSOdel1>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=842 |title=Delta1 Apodis |author =Watson, Christopher |date=25 August 2009 |work=The International Variable Star Index|publisher=American Association of Variable Star Observers|access-date=30 March 2016}}</ref> with pulsations of multiple periods of 68.0, 94.9 and 101.7 days.<ref name=tabur>{{cite journal | title=Long-term photometry and periods for 261 nearby pulsating M giants | author=Tabur, V. | author2=Bedding, T.R. |author3=Kiss, L.L. | author4=Moon, T.T. | author5=Szeidl, B. | author6=Kjeldsen, H. |date=2009 |journal=Monthly Notices of the Royal Astronomical Society |volume= 400 | issue =4 |pages= 1945–61 |doi=10.1111/j.1365-2966.2009.15588.x |arxiv = 0908.3228 |bibcode = 2009MNRAS.400.1945T | s2cid=15358380 }}</ref> Delta<sup>2</sup> is an orange giant star of spectral type K3III,<ref>{{cite journal|bibcode=1975mcts.book.....H|title=University of Michigan Catalogue of two-dimensional spectral types for the HD stars. Volume I. Declinations −90_ to −53_ƒ0|journal=University of Michigan Catalogue of Two-dimensional Spectral Types for the HD Stars. Volume I. Declinations −90° to −53.0°|last1=Houk|first1=N.|last2=Cowley|first2=A. P.|year=1975}}</ref> located 550 ± 10 light-years away,<ref name=dr2/> with a magnitude of 5.3. The separate components can be resolved with the naked eye.<ref name=ridpath01/>

The fifth-brightest star is [[Astronomy:Zeta Apodis|Zeta Apodis]] at magnitude 4.8,<ref name=arnold/> 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.<ref name=Mcdonald/> It is 300 ± 4 light-years distant.<ref name=dr2/> Near Zeta is [[Astronomy:Iota Apodis|Iota Apodis]], a [[Astronomy:Binary star|binary star]] system 1,040 ± 60 light-years distant,<ref name=dr2/> 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.<ref>{{cite journal | title=Dynamical and physical properties of 22 binaries discovered by W. S. Finsen|author1=Docobo, J.A. |author2=Andrade, M. |journal=Monthly Notices of the Royal Astronomical Society|volume =428 |issue =1| pages=321–39| year= 2013|doi=10.1093/mnras/sts045 | bibcode=2013MNRAS.428..321D|doi-access=free}}</ref>

[[Astronomy:Eta Apodis|Eta Apodis]] is a [[Astronomy:A-type main-sequence star|white main sequence star]] located 140.8 ± 0.9 light-years distant.<ref name=dr2/> 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 [[Astronomy:Infrared excess|excess]] of 24&nbsp;μm infrared radiation, which may be caused by a [[Astronomy:Debris disk|debris disk]] of dust orbiting at a distance of more than 31 [[Astronomy:Astronomical unit|astronomical unit]]s from it.<ref name="apj698">{{cite journal | last1=Plavchan | first1=Peter | last2=Werner | first2=M.W. | last3=Chen | first3=C.H. | last4=Stapelfeldt | first4=K.R. | last5=Su | first5=K.Y.L. | last6=Stauffer | first6=J.R. | last7=Song | first7=I. | title=New Debris Disks Around Young, Low-Mass Stars Discovered with the Spitzer Space Telescope | journal=The Astrophysical Journal | volume=698 | issue=2 | pages=1068–94 |date=2009 | doi=10.1088/0004-637X/698/2/1068 | bibcode=2009ApJ...698.1068P |arxiv = 0904.0819 | s2cid=51417657 }}</ref><!-- cites prev 2 sentences -->

[[Astronomy:Theta Apodis|Theta Apodis]] is a cool red giant of spectral type M7 III located 350 ± 30 light-years distant.<ref name=dr2/> It shines with a luminosity approximately 3879 times that of the Sun and has a surface temperature of 3151 K.<ref name=Mcdonald/> A semiregular variable, it varies by 0.56 magnitudes with a period of 119 days<ref name=mnras355_2_601>{{cite journal| last1=Yeşilyaprak | first1=C. | last2=Aslan | first2=Z. | title=Period-luminosity relation for M-type semiregular variables from Hipparcos parallaxes | journal=[[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] | volume=355 | issue=2 | pages=601–07 |date=2004 | doi=10.1111/j.1365-2966.2004.08344.x | bibcode=2004MNRAS.355..601Y| doi-access=free }}</ref>—or approximately 4 months.<ref name=ridpath01/> It is losing mass at the rate of {{nowrap|1.1 × 10<sup>−7</sup>}} times the mass of the Sun per year through its [[Astronomy:Stellar wind|stellar wind]]. Dusty material ejected from this star is interacting with the surrounding [[Astronomy:Interstellar medium|interstellar medium]], forming a [[Astronomy:Bow shock|bow shock]] as the star moves through the galaxy.<ref name=aaa537_A35>{{cite journal | last1=Cox | first1=N.L.J. | last2=Kerschbaum | first2=F. | last3=van Marle | first3=A.-J. | last4=Decin | first4=L. | last5=Ladjal | first5=D. | last6=Mayer | first6=A. | last7=Groenewegen | first7=M. A. T. | last8=van Eck | first8=S. | last9=Royer | first9=P. | last10=Ottensamer | first10=R. | last11=Ueta | first11=T. | last12=Jorissen | first12=A. | last13=Mecina | first13=M. | last14=Meliani | first14=Z. | last15=Luntzer | first15=A. | last16=Blommaert | first16=J.A.D.L. | last17=Posch | first17=Th. | last18=Vandenbussche, B. | last19=Waelkens, C. | title=A far-infrared survey of bow shocks and detached shells around AGB stars and red supergiants | journal=Astronomy & Astrophysics | volume=537 | page=A35 |date=2012 | doi=10.1051/0004-6361/201117910 | bibcode=2012A&A...537A..35C |arxiv = 1110.5486 | s2cid=56041336 }} See table 1, IRAS 14003-7633.</ref> [[Astronomy:NO Apodis|NO Apodis]] is a red giant of spectral type M3III that varies between magnitudes 5.71 and 5.95.<ref name=AAVSONO>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=815 |title=NO Apodis |author =Watson, Christopher |date=25 August 2009 |work=The International Variable Star Index|publisher=American Association of Variable Star Observers|access-date=31 March 2015}}</ref> Located 780 ± 20 light-years distant, it shines with a luminosity estimated at 2059 times that of the Sun and has a surface temperature of 3568 K.<ref name=Mcdonald/> [[Astronomy:S Apodis|S Apodis]] is a rare [[Astronomy:R Coronae Borealis variable|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.<ref name=tisserand>{{cite journal |author1=Tisserand|author2=Clayton|author3=Welch|author4=Pilecki|author5=Wyrzykowski|author6=Kilkenny|title=The Ongoing Pursuit of R Coronae Borealis Stars: ASAS-3 Survey Strikes Again |date=2012 |bibcode=2013A&A...551A..77T |journal =Astronomy & Astrophysics |volume = 551 | id = A77 |pages= 22|arxiv = 1211.2475 |doi = 10.1051/0004-6361/201220713 |s2cid=59060842}}</ref> [[Astronomy:R Apodis|R Apodis]] is a star that was given a [[Astronomy:Variable star designation|variable star designation]], yet has turned out not to be variable. Of magnitude 5.3,<ref name=arnold/> it is another orange giant.

Two star systems have had [[Astronomy:Exoplanet|exoplanet]]s discovered by [[Astronomy:Doppler spectroscopy|doppler spectroscopy]], and the substellar companion of a third star system—the sunlike star [[Astronomy:HD 131664|HD 131664]]—has since been found to be a [[Astronomy:Brown dwarf|brown dwarf]] with a calculated mass of the companion to 23 times that of Jupiter (minimum of 18 and maximum of 49 Jovian masses).<ref name="ReffertQuirrenbach">{{cite journal|author1=Reffert, S.|author2=Quirrenbach, A.|title=Mass constraints on substellar companion candidates from the re-reduced Hipparcos intermediate astrometric data: nine confirmed planets and two confirmed brown dwarfs|date=2011|journal=Astronomy & Astrophysics|volume=527|pages=A140 |doi=10.1051/0004-6361/201015861|bibcode=2011A&A...527A.140R|arxiv=1101.2227|s2cid=54986291}}</ref> [[Astronomy:HD 134606|HD 134606]] is a yellow sunlike star of spectral type G6IV that has begun expanding and cooling off the [[Astronomy:Main sequence|main sequence]].<ref name="Gray">{{cite journal | last1=Gray | first1=R.O.| last2=Corbally | first2=C.J.| last3=Garrison | first3=R.F.| last4=McFadden | first4=M.T. | last5=Bubar | first5=E.J. | last6=McGahee | first6=C.E.| last7=O'Donoghue | first7=A.A.| last8=Knox | first8=E.R.| title=Contributions to the Nearby Stars (NStars) Project: spectroscopy of stars earlier than M0 within 40 pc-The Southern Sample | journal=[[Astronomy:The Astronomical Journal|The Astronomical Journal]] | volume=132 | issue=1 | pages=161–170 | date=July 2006 | doi=10.1086/504637 | bibcode=2006AJ....132..161G | arxiv=astro-ph/0603770| s2cid=119476992}}</ref> Three planets orbit it with periods of 12, 59.5 and 459 days, successively larger as they are further away from the star.<ref>{{cite journal | title=Tests of in situ Formation Scenarios for Compact Multiplanet Systems |author=Schlaufman, Kevin C. | journal=The Astrophysical Journal |volume = 790|issue =2| id= 91 |pages= 11 |year=2014| doi=10.1088/0004-637X/790/2/91 |bibcode=2014ApJ...790...91S|arxiv=1402.7075|s2cid=8130257 }}</ref> [[Astronomy:HD 137388|HD 137388]] is another star—of spectral type K2IV—that is cooler than the Sun and has begun cooling off the main sequence.<ref name="Gray"/> 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.<ref name=" Bonfanti 2015">{{cite journal|author1=Bonfanti, A. |author2=Ortolani, S. |author3=Piotto, G. |author4=Nascimbeni, V. |date=2015|title=Revising the ages of planet-hosting stars|journal=Astronomy & Astrophysics|volume=575|issue=A18|pages=17|doi=10.1051/0004-6361/201424951 |bibcode=2015A&A...575A..18B|arxiv = 1411.4302 |s2cid=54555839 }}</ref> 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).<ref name=HARPSXXX>{{cite journal |title=The HARPS Search for Southern Extra-solar Planets. XXX. Planetary Systems around Stars with Solar-like Magnetic Cycles and Short-term Activity Variation |author1=Dumusque, X. |author2=Lovis, C. |author3=Ségransan, D. |author4=Mayor, M. |author5=Udry, S. |author6=Benz, W. |author7=Bouchy, F. |author8=Lo Curto, G. |author9=Mordasini, C. |author10=Pepe, F. |author11=Queloz, D. |author12=Santos, N. C. |author13=Naef, D. |journal=Astronomy & Astrophysics |volume=535 |pages=A55–A66 |doi=10.1051/0004-6361/201117148 |url=http://cds.aanda.org/articles/aa/full_html/2011/11/aa17148-11/aa17148-11.html |arxiv=1107.1748 |bibcode=2011A&A...535A..55D |year=2011 |s2cid=119192207 |access-date=2016-05-29 |archive-url=https://web.archive.org/web/20150529071847/http://cds.aanda.org/articles/aa/full_html/2011/11/aa17148-11/aa17148-11.html |archive-date=2015-05-29 |url-status=dead }}</ref>

===Deep-sky objects===
[[File:Potw1431a.jpg|thumb|[[Astronomy:Globular cluster|Globular cluster]] IC 4499 taken by Hubble Space Telescope.<ref>{{cite news|title=IC 4499: A globular cluster's age revisited|url=http://www.spacetelescope.org/images/potw1431a/|access-date=5 August 2014|work=ESA/Hubble Picture of the Week}}</ref>|alt=A spherical shaped group of a multitude of stars]]

The [[Astronomy:Milky Way|Milky Way]] covers much of the constellation's area.<ref name="Inglis04">{{Cite book |last = Inglis |first = Mike |title = Astronomy of the Milky Way: The observer's guide to the southern Milky Way |publisher = Springer |location=New York, New York |date = 2004 |pages = 124–27 |url = https://books.google.com/books?id=1r0qvMjSCGAC&pg=SA3-PA53 |isbn = 978-1-85233-709-4}}</ref> Of the deep-sky objects in Apus, there are two prominent [[Astronomy:Globular cluster|globular cluster]]s—[[Astronomy:NGC 6101|NGC 6101]] and [[Astronomy:IC 4499|IC 4499]]—and a large faint [[Astronomy:Nebula|nebula]] that covers several degrees east of Beta and Gamma Apodis.<ref name=hartungs>{{cite book |author1=Malin, David |author2=Frew, David J. | title = Hartung's Astronomical Objects for Southern Telescopes, with an Addendum for Northern Observatories: A Handbook for Amateur Observers |publisher = Melbourne University Publishing |year=1995 |location= Melbourne, Victoria | url=https://books.google.com/books?id=FTsDDQAAQBAJ&pg=PT216 |isbn=978-0-522-87124-1}}</ref> NGC 6101 is a globular cluster of apparent magnitude 9.2 located around 50,000 light-years distant from Earth,<ref name=imaging>{{cite book |title=Imaging the Southern Sky: An Amateur Astronomer's Guide |first1=Stephen |last1=Chadwick |first2=Ian |last2=Cooper |page=240 |isbn=978-1-4614-4750-4 |year=2012|publisher=Springer }}</ref> which is around 160 light-years across. Around 13 billion years old, it contains a high concentration of massive bright stars known as [[Astronomy:Blue straggler|blue straggler]]s, thought to be the result of two stars merging.<ref name="O'Meara">{{cite book |last=O'Meara |first= Stephen James |title= Deep Sky Companions: The Caldwell Objects |date=2003 |publisher= Cambridge University Press |location= Cambridge, United Kingdom |isbn= 978-0-521-82796-6 |pages= 409–412}}</ref> IC 4499 is a loose globular cluster in the medium-far [[Astronomy:Galactic halo|galactic halo]];<ref name=ferraro>{{cite journal |last1= Ferraro |first1=I. |last2=Ferraro |first2=F.R. |last3=Pecci |first3=F. Fusi |last4=Corsi |first4 = C.E. |last5=Buonanno |first5 = R. |date= August 1995 |title= Young globular clusters in the Milky Way: IC 4499 |journal= [[Organization:Monthly Notices of the Royal Astronomical Society|Monthly Notices of the Royal Astronomical Society]] |volume=275 |issue=4 |pages=1057–1076 |bibcode = 1995MNRAS.275.1057F |doi= 10.1093/mnras/275.4.1057|doi-access=free }}</ref> its apparent magnitude is 10.6.<ref name=seds>{{cite web |url = http://spider.seds.org/ngc/ngc.cgi?I4499 |title = IC 4499 |publisher = Students for the Exploration and Development of Space |access-date = 22 April 2012 |last = Frommert |first = Hartmut}}</ref>

The galaxies in the constellation are faint.<ref name=hartungs/> IC 4633 is a very faint spiral galaxy surrounded by a vast amount of Milky Way line-of-sight integrated flux nebulae—large faint clouds thought to be lit by large numbers of stars.<ref name=imaging/>

==See also==
* [[Astronomy:IAU designated constellations|IAU-recognized constellations]]

==Notes==
{{notelist}}
{{clear}}

==References==
{{Reflist}}

==External links==
{{Commons}}
* [http://www.allthesky.com/constellations/apus/constell.html The Deep Photographic Guide to the Constellations: Apus]
* [http://astrojan.nhely.hu/apus.htm The clickable Apus]
{{Sky|16|00|00|-|75|00|00|10}}

{{Stars of Apus}}
{{navconstel}}
{{DEFAULTSORT:Apus}}
[[Category:Apus| ]]
[[Category:Southern constellations]]
[[Category:Constellations listed by Petrus Plancius]]

{{Sourceattribution|Apus}}