View source for Astronomy:Ara (constellation)

{{Short description|Constellation in the southern celestial hemisphere}}
{{Infobox constellation
| name = Ara
| abbreviation = Ara{{sfn|Ridpath|Tirion|2001|pp=82–83}}
| genitive = Arae{{sfn|Ridpath|Tirion|2001|pp=82–83}}
| pronounce = {{IPAc-en|ˈ|ɛər|ə}}, genitive {{IPAc-en|ˈ|ɛər|iː}}{{efn|name=pronunciation}}
| symbolism = the Altar{{sfn|Ridpath|Tirion|2001|pp=82–83}}
| RA = {{RA|16|34|16.9497}}–{{RA|18|10|41.3407}}<ref name=boundary>{{Cite journal | title=Ara, constellation boundary | journal=The Constellations |url=https://www.iau.org/public/themes/constellations/#ara | access-date=14 February 2014 }}</ref>
| dec= {{dec|-45.4859734}}–{{dec|-67.6905823}}<ref name=boundary/>
| family = Hercules
| areatotal = 237
| arearank = 63rd
| numbermainstars = 8{{sfn|Ridpath|Tirion|2001|pp=82–83}}
| numberbfstars = 17
| numberstarsplanets = 7
| numberbrightstars = 2
| numbernearbystars = 3
| brighteststarname = [[Astronomy:Beta Arae|β Ara]]
| starmagnitude = 2.84
| neareststarname = [[Astronomy:Gliese 674|Gliese 674]]
| stardistancely = 14.80
| stardistancepc = 4.54
| numbermessierobjects = 0
| meteorshowers = 0
| bordering =
  {{plainlist |
* [[Astronomy:Corona Australis|Corona Australis]]
* [[Astronomy:Scorpius|Scorpius]]
* [[Astronomy:Norma (constellation)|Norma]]
* [[Astronomy:Triangulum Australe|Triangulum Australe]]
* [[Astronomy:Apus|Apus]]
* [[Astronomy:Pavo (constellation)|Pavo]]
* [[Astronomy:Telescopium|Telescopium]]
  }}
| latmax = 25
| latmin = [[Earth:South Pole|90]]
| month = July
| notes =
}}

'''Ara''' ([[Social:Latin|Latin]] for "the Altar") is a [[Astronomy:Southern celestial hemisphere|southern]] [[Astronomy:Constellation|constellation]] between [[Astronomy:Scorpius|Scorpius]], [[Astronomy:Telescopium|Telescopium]], [[Astronomy:Triangulum Australe|Triangulum Australe]], and [[Astronomy:Norma (constellation)|Norma]]. It was (as {{lang-grc|Βωμός|Bōmǒs||label=none}}) one of the Greek bulk (namely 48) described by the 2nd-century astronomer [[Biography:Ptolemy|Ptolemy]], and it remains one of the [[Astronomy:IAU designated constellations|88 modern constellations]] designated by the [[Organization:International Astronomical Union|International Astronomical Union]].

The orange supergiant [[Astronomy:Beta Arae|Beta Arae]], to us its brightest star measured with near-constant [[Astronomy:Apparent magnitude|apparent magnitude]] of 2.85, is marginally brighter than blue-white [[Astronomy:Alpha Arae|Alpha Arae]]. Seven star systems are known to host planets. Sunlike [[Astronomy:Mu Arae|Mu Arae]] hosts four known planets. [[Astronomy:Gliese 676|Gliese 676]] is a (gravity-paired) binary [[Astronomy:Red dwarf|red dwarf]] system with four known planets.

The Milky Way crosses the northwestern part of Ara. Within the constellation is [[Astronomy:Westerlund 1|Westerlund 1]], a [[Astronomy:Super star cluster|super star cluster]] that contains the [[Astronomy:Red supergiant|red supergiant]] [[Astronomy:Westerlund 1-26|Westerlund 1-26]], [[Astronomy:List of largest stars|one of the largest stars known]].

== History ==
<!-- Deleted image removed: [[File:46-Ara-Constellation.PNG|left|thumb|350px|Ara as depicted on The Manuchihr Globe made in Mashhad 1632-33 AD. Adilnor Collection, Sweden.]] -->
In ancient [[Religion:Greek mythology|Greek mythology]], Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans.{{sfn|Ridpath|Tirion|2001|pp=82–83}} One of the southernmost constellations depicted by [[Biography:Ptolemy|Ptolemy]],<ref name=barentine>{{cite book | title=The Lost Constellations | author=Barentine, John C. | chapter= Officina Typographica | date=23 November 2015 | page=13 | isbn=978-3-319-22794-8}}</ref> it had been recorded by [[Biography:Aratus|Aratus]] in 270 BC as lying close to the horizon, and the [[Astronomy:Almagest|Almagest]] portrays stars as far south as [[Astronomy:Gamma Arae|Gamma Arae]]. Professor [[Biography:Bradley Schaefer|Bradley Schaefer]] proposes such Ancients must have been able to see as far south as [[Astronomy:Zeta Arae|Zeta Arae]], for a pattern that looked like an altar.<ref>{{cite journal | title=The latitude and epoch for the formation of the southern Greek constellations | author=Schaefer, Bradley E. |journal= Journal for the History of Astronomy| issn= 0021-8286|volume= 33| series= 4|issue=113| pages= 313–50 |year=2002| bibcode=2002JHA....33..313S| doi=10.1177/002182860203300401| s2cid=122459258 }}</ref>

[[File:Ara Bode.jpg|thumb|left|Johann Elert Bode's illustration of Ara, from his ''Uranographia'' (1801)]]
In illustrations, Ara is usually depicted as compact classical altar with its smoke 'rising' southward.{{sfn|Ridpath, ''Star Tales'' Ara}} However, depictions often vary. In the early days of printing, a 1482 woodcut of [[Biography:Gaius Julius Hyginus|Gaius Julius Hyginus]]'s classic ''Poeticon Astronomicon'' depicts the altar as surrounded by demons.<ref name=Kanas>{{cite book|last=Kanas|first=Nick|title=History, Artistry, and Cartography|edition=Second|date=2012|publisher=Praxis Publishing|location=Chichester, U.K.|isbn=978-1-4614-0916-8|page=136|doi=10.1007/978-1-4614-0917-5|s2cid=239353025 |url=https://cds.cern.ch/record/1481587}}</ref> Johann Bayer in 1603 depicted Ara as an altar with burning incense. Hyginus depicted the same though his featured devils on either side of the flames. Willem Blaeu, a Dutch uranographer of the 16th and 17th centuries, drew Ara as an altar for sacrifices, with a burning animal offering unusually whose smoke rises northward, represented by [[Astronomy:Alpha Arae|Alpha Arae]].

''The Castle of Knowledge'' by Robert Record of 1556 lists the constellation stating that "Under the Scorpions tayle, standeth the Altar.";<ref>''The Castle of Knowledge containing the Explication of the Sphere both Celestiall and Materiall, etc.'', 1st edition, 1556; Robert Record, London; R. Wolfe (printer) STC 20796</ref> a decade later a translation of a fairly recent mainly astrological work by Marcellus Palingenius of 1565, by Barnabe Googe states "Here mayst thou both the Altar, and the myghty Cup beholde."<ref>''The zodiake of life written by the godly and zealous poet Marcellus Palingenius Stellatus, wherein are conteyned twelve bookes, new edition'', 1565 (1 vol.); Barnabe Googe, London; Henry Denham (printer), for Rafe Newberye dwelling in Fleete streate, Anno. 1565. Aprilis. 18; STC 1915</ref>

=== Equivalents ===
In Chinese astronomy, the stars of the constellation Ara lie within ''[[Astronomy:Azure Dragon|The Azure Dragon of the East]]'' (東方青龍, ''Dōng Fāng Qīng Lóng'').{{sfn|AEEA|2006}} Five stars of Ara formed Guī (龜), a [[Biology:Tortoise|tortoise]], while another three formed Chǔ (杵), a pestle.

The Wardaman people of the Northern Territory in Australia saw the stars of Ara and the neighbouring constellation [[Astronomy:Pavo (constellation)|Pavo]] as flying foxes.<ref name="darksparklers">{{cite book |last=Harney |first=Bill Yidumduma |author2=Cairns, Hugh C. |title=Dark Sparklers |publisher=Hugh C. Cairns |location=Merimbula, New South Wales |date=2004 |orig-year=2003 |edition=Revised |page=201 |isbn=978-0-9750908-0-0}}</ref>

==Characteristics==
Covering 237.1 square degrees and hence 0.575% of the sky, Ara ranks 63rd 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= 18 September 2016}}</ref> Its position in the Southern Celestial Hemisphere means that the whole [[Astronomy:Constellation|constellation]] is visible to observers south of 22°N.<ref name=tirionconst/>{{efn|1=Although parts of the constellation technically rise above the horizon to observers between the 22°N and 44°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.<ref name=tirionconst/>}} Scorpius runs along the length of its northern border, while Norma and Triangulum Australe border it to the west, [[Astronomy:Apus|Apus]] to the south, and Pavo and Telescopium to the east respectively. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union, is "Ara".<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= 18 September 2016}}</ref>}} are defined by a polygon of twelve segments. In the [[Astronomy:Equatorial coordinate system|equatorial coordinate system]], the [[Right ascension|right ascension]] coordinates of these borders lie between {{RA|16|36.1}} and {{RA|18|10.4}}, while the [[Declination|declination]] coordinates are between −45.49° and −67.69°.<ref name=boundary/>

== Features ==
[[Image:Constellation Ara.jpg|thumb|left|200px|The constellation Ara as it can be seen by the naked eye.]]

=== Stars ===
Bayer gave eight stars [[Astronomy:Bayer designation|Bayer designation]]s, labelling them Alpha through to Theta, though he had never seen the constellation directly as it never rises above the horizon in Germany. After charting the southern constellations, French astronomer Nicolas-Louis de Lacaille recharted the stars of Ara from Alpha though to Sigma, including three pairs of stars next to each other as Epsilon, Kappa and Nu.{{sfn|Wagman|2003|pp=42–43}}

Ara contains part of the Milky Way to the south of Scorpius and thus has rich star fields.{{sfn|Ridpath|Tirion|2001|pp=82–83}} Within the constellation's borders, there are 71 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/>

Just shading Alpha Arae, Beta Arae is the brightest star in the constellation.<ref>{{cite book |last=Thompson |first=Mark |title=A Down to Earth Guide to the Cosmos |publisher=Random House |date=2013 |isbn=978-1-4481-2691-0 |url=https://books.google.com/books?id=SOfRFJBy-igC&pg=PT77}}</ref> It is an orange-hued star of spectral type K3Ib-IIa that has been classified as a supergiant or bright giant,<ref name=aaa395_97>{{cite journal | last1=De Medeiros | first1=J. R. | last2=Udry | first2=S. | last3=Burki | first3=G. | last4=Mayor | first4=M. | title=A catalog of rotational and radial velocities for evolved stars. II. Ib supergiant stars | journal=Astronomy and Astrophysics | volume=395 | pages=97–98 |date=November 2002 | doi=10.1051/0004-6361:20021214 | bibcode=2002A&A...395...97D | url=http://www.aanda.org/articles/aa/pdf/2002/43/aa2890.pdf |archive-url=https://ghostarchive.org/archive/20221009/http://www.aanda.org/articles/aa/pdf/2002/43/aa2890.pdf |archive-date=2022-10-09 |url-status=live | doi-access=free }}</ref> that is around 650 light-years from Earth.<ref name=aaa474_2_653/> It is around 8.21 times as massive and 5,636 times as luminous as the Sun.<ref name=gaia>{{cite journal|bibcode=2015A&A...582A..49H|arxiv=1506.06095|title=Gaia FGK benchmark stars: Effective temperatures and surface gravities|journal=Astronomy & Astrophysics|volume=582|pages=A49|last1=Heiter|first1=U.|last2=Jofré|first2=P.|last3=Gustafsson|first3=B.|last4=Korn|first4=A. J.|last5=Soubiran|first5=C.|last6=Thévenin|first6=F.|year=2015|doi=10.1051/0004-6361/201526319|s2cid=53391939}}</ref> At apparent magnitude 2.85, this difference in brightness between the two is undetectable by the unaided eye.<ref>{{cite web | first1=James B. | last1=Kaler | work=Stars | title=BETA ARA (Beta Arae) | publisher=University of Illinois | url=http://stars.astro.illinois.edu/sow/betaara.html | access-date=17 September 2016}}</ref> Close to Beta Arae is [[Astronomy:Gamma Arae|Gamma Arae]], a blue-hued supergiant of spectral type B1Ib. Of apparent magnitude 3.3, it is 1110 ± 60  light-years from Earth.<ref name=aaa474_2_653/> It has been estimated to be between 12.5 and 25 times as massive as the Sun,<ref name=mnras410_1_190>{{cite journal | last1=Tetzlaff | first1=N. | last2=Neuhäuser | first2=R. | last3=Hohle | first3=M. M. | title=A catalogue of young runaway Hipparcos stars within 3 kpc from the Sun | journal=Monthly Notices of the Royal Astronomical Society | volume=410 | issue=1 | pages=190–200 |date=2011 | doi=10.1111/j.1365-2966.2010.17434.x | bibcode=2011MNRAS.410..190T |arxiv = 1007.4883 | s2cid=118629873 }}</ref><ref name=aaa463_3_1093>{{cite journal | last1=Lefever | first1=K. | last2=Puls | first2=J. | last3=Aerts | first3=C. | title=Statistical properties of a sample of periodically variable B-type supergiants. Evidence for opacity-driven gravity-mode oscillations | journal=Astronomy and Astrophysics | volume=463 | issue=3 | pages=1093–1109 |date=March 2007 | doi=10.1051/0004-6361:20066038 | bibcode=2007A&A...463.1093L |arxiv = astro-ph/0611484 | s2cid=8783008 }}</ref> and have around 120,000 times its luminosity.<ref name=aaa463_3_1093/>

Alpha Arae is a blue-white main sequence star of magnitude 2.95, that is 270 ± 20 light-years from Earth.<ref name=aaa474_2_653>{{cite journal | title=Validation of the new Hipparcos reduction | last=van Leeuwen | first=F. | journal=Astronomy and Astrophysics | volume=474 | issue=2 |date=November 2007 | pages=653–64 | doi=10.1051/0004-6361:20078357 | bibcode=2007A&A...474..653V |arxiv = 0708.1752 | s2cid=18759600 }}</ref> This star is around 9.6 times as massive as the Sun,<ref name=m07 /> and has an average of 4.5 times its radius.<ref name=aaa505_2_687>{{cite journal | last1=Meilland | first1=A. | last2=Stee | first2=Ph. | last3=Chesneau | first3=O. | last4=Jones | first4=C. | title=VLTI/MIDI observations of 7 classical Be stars | journal=Astronomy and Astrophysics | volume=505 | issue=2 | pages=687–93 |date=2009 | doi=10.1051/0004-6361/200911960 | bibcode=2009A&A...505..687M |arxiv = 0908.1239 | s2cid=12694072 }}</ref> It is  5,800 times as luminous as the Sun,<ref name=m07>{{cite journal | title=First direct detection of a Keplerian rotating disk around the Be star α Arae using AMBER/VLTI | first1=A. | last1=Meilland | journal=Astronomy and Astrophysics | volume=464 | issue=1 |date=March 2007 | pages=59–71 | doi=10.1051/0004-6361:20064848 | bibcode=2007A&A...464...59M |arxiv = astro-ph/0606404 | s2cid=55225830 |display-authors=0| url=https://hal.archives-ouvertes.fr/hal-00078768 }}. See Tables 1 and 4 for parameters of the star, circumstellar disk, and polar winds.</ref> its energy emitted from its [[Astronomy:Stellar atmosphere|outer envelope]] at an [[Astronomy:Effective temperature|effective temperature]] of 18,044&nbsp;K.<ref name=aaa505_2_687/> A [[Astronomy:Be star|Be star]], Alpha Arae is surrounded by a dense equatorial disk of material in Keplerian (rather than uniform) rotation.  The star is losing mass by a polar [[Astronomy:Stellar wind|stellar wind]] with a terminal velocity of approximately 1,000&nbsp;km/s.<ref name=m07/><ref>{{cite journal | title=First VLTI/MIDI observations of a Be star: Alpha Arae |author1=Chesneau, O. |author2=Meilland, A. |author3=Rivinius, T. |author4=Stee, Ph. |author5=Jankov, S. |author6=Domiciano de Souza, A. |author7=Graser, U. |author8=Herbst, T. |author9=Janot-Pacheco, E. |author10=Koehler, R. |author11=Leinert, C. |author12=Morel, S. |author13=Paresce, F. |author14=Richichi, A. |author15=Robbe-Dubois, S. |journal=Astronomy and Astrophysics|volume=435|issue=1 |year=2005| pages=275–287|doi=10.1051/0004-6361:20041954|bibcode=2005A&A...435..275C|arxiv = astro-ph/0501162 |s2cid=16747094 }}</ref>

The third brightest star in Ara at magnitude 3.13 is [[Astronomy:Zeta Arae|Zeta Arae]],<ref name=kalerzeta>{{cite web |last1=Kaler |first1=Jim |title=Zeta Arae |url=http://stars.astro.illinois.edu/sow/zetaara.html |website=Stars |publisher=University of Illinois |date=13 July 2012|access-date=12 September 2019}}</ref> an orange giant of spectral type K3III that is located 490 ± 10 light-years from Earth.<ref name=aaa474_2_653/> Around 7–8 times as massive as the Sun, it has swollen to a diameter around 114 times that of the Sun and is 3800 times as luminous.<ref name=cruzalebes>{{cite journal|bibcode=2013MNRAS.434..437C|arxiv=1306.3288|title=Fundamental parameters of 16 late-type stars derived from their angular diameter measured with VLTI/AMBER|journal=Monthly Notices of the Royal Astronomical Society |volume=434|issue=1|pages=437|last1=Cruzalèbes|first1=P.|last2=Jorissen|first2=A.|last3=Rabbia|first3=Y.|last4=Sacuto|first4=S.|last5=Chiavassa|first5=A.|last6=Pasquato|first6=E.|last7=Plez|first7=B.|last8=Eriksson|first8=K.|last9=Spang|first9=A.|last10=Chesneau|first10=O.|year=2013|doi=10.1093/mnras/stt1037|s2cid=49573767}}</ref> Were it not dimmer by intervening interstellar dust, it would be significantly brighter at magnitude 2.11.<ref name=kalerzeta/>

[[Astronomy:Delta Arae|Delta Arae]] is a blue-white main sequence star of spectral type B8Vn and magnitude 3.6, 198 ± 4 light-years from Earth.<ref name=aaa474_2_653/> It is around 3.56 times as massive as the Sun.<ref name=apjss192_1_2>{{cite journal | last1=Shaya | first1=Ed J. | last2=Olling | first2=Rob P. | title=Very Wide Binaries and Other Comoving Stellar Companions: A Bayesian Analysis of the Hipparcos Catalogue | journal=The Astrophysical Journal Supplement | volume=192 | issue=1 | page=2 |date=January 2011 | doi=10.1088/0067-0049/192/1/2 | bibcode=2011ApJS..192....2S |arxiv = 1007.0425 | s2cid=119226823 }}</ref>

[[Astronomy:Epsilon1 Arae|Epsilon<sup>1</sup> Arae]] is an orange giant of apparent magnitude 4.1, 360 ± 10 light-years distant from Earth.<ref name=aaa474_2_653/> It is around 74% more massive than the Sun. At an age of about 1.7&nbsp;billion years, the [[Astronomy:Stellar atmosphere|outer envelope]] of the star has expanded to almost 34 times the Sun's radius.<ref name=aaa458_2_609>{{cite journal | last1=da Silva | first1=L. | last2=Girardi | first2=L. | last3=Pasquini | first3=L. | last4=Setiawan | first4=J. | last5=von der Lühe | first5=O. | last6=de Medeiros | first6=J. R. | last7=Hatzes | first7=A. | last8=Döllinger | first8=M. P. | last9=Weiss | first9=A. | title=Basic physical parameters of a selected sample of evolved stars | journal=Astronomy and Astrophysics | volume=458 | issue=2 |date=November 2006 | pages=609–623 | doi=10.1051/0004-6361:20065105 | bibcode=2006A&A...458..609D |arxiv = astro-ph/0608160 | s2cid=9341088 }}</ref>

[[Astronomy:Eta Arae|Eta Arae]] is an orange giant of apparent magnitude 3.76, located 299 ± 5 light-years distant from Earth.<ref name=aaa474_2_653/> Estimated to be around five billion years old, it has reached the [[Astronomy:Giant star|giant star]] stage of its [[Astronomy:Stellar evolution|evolution]]. With 1.12 times the mass of the Sun, it has an [[Astronomy:Stellar atmosphere|outer envelope]] that has expanded to 40 times the Sun's radius.<ref name=jofre2015>{{cite journal | title=Stellar parameters and chemical abundances of 223 evolved stars with and without planets | journal=Astronomy & Astrophysics | volume=574 | pages=A50 | year=2015 | last1=Jofré | first1=E. | last2=Petrucci | first2=R. | last3=Saffe | first3=C. | last4=Saker | first4=L. | last5=de la Villarmois | first5=E. Artur | last6=Chavero | first6=C. | last7=Gómez | first7=M. | last8=Mauas | first8=P. J. D. | bibcode=2015A&A...574A..50J | doi=10.1051/0004-6361/201424474 | arxiv=1410.6422 | s2cid=53666931 }}</ref> The star is now spinning so slowly that it takes more than eleven years to complete a single rotation.<ref name=aaa421_241>{{cite journal | last1=Setiawan | first1=J. | last2=Pasquini | first2=L. | last3=da Silva | first3=L. | last4=Hatzes | first4=A. P. | last5=von der Lühe | first5=O. | last6=Girardi | first6=L. | last7=de Medeiros | first7=J. R. | last8=Guenther | first8=E. | title=Precise radial velocity measurements of G and K giants. Multiple systems and variability trend along the Red Giant Branch | journal=Astronomy and Astrophysics | volume=421 | pages=241–254 |date=July 2004 | doi=10.1051/0004-6361:20041042-1 | bibcode=2004A&A...421..241S | doi-access=free }}</ref>

[[Astronomy:GX 339-4|GX 339-4]] (V821 Arae) is a moderately strong variable galactic [[Astronomy:X-ray binary#Low-mass X-ray binary|low-mass X-ray binary]] (LMXB) source<ref>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GX+339-4 SIMBAD]</ref><ref>Bradt, H.V.D., and McClintock, J.E., Annu. Rev. Astron. Astrophys., 21, 13-66 (1983)</ref> and [[Astronomy:Black hole|black-hole]] candidate that flares from time to time. From spectroscopic measurements, the mass of the black-hole was found to be at least of 5.8 solar masses.<ref>{{Cite journal|title = Dynamical Evidence for a Black Hole in GX 339-4|author1=Hynes, R. I. |author2=Steeghs, D. |author3=Casares, J. |author4=Charles, P. A. |author5=O'Brien, K. |date = February 2003|journal = The Astrophysical Journal| volume = 583| issue = 2, pp. L95–L98|doi = 10.1086/368108|bibcode=2003ApJ...583L..95H |pages=L95–L98|arxiv = astro-ph/0301127 |s2cid=16820881 }}</ref>

[[Astronomy:Exoplanet|Exoplanet]]s have been discovered in seven star systems in the constellation.<ref name=bagnall>{{Cite book|title=The Star Atlas Companion : What You Need to Know about the Constellations|last=Bagnall|first= Philip M. |date=2012|publisher=[[Company:Springer Science+Business Media|Springer]] |pages= 50–54| location=New York | isbn=9781461408307|oclc=794225463}}</ref>  [[Astronomy:Mu Arae|Mu Arae]] (Cervantes<ref name="IAU-LSN">{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |access-date=30 July 2018}}</ref>) is a sunlike star that hosts four planets.<ref name="pepe">{{Cite journal|author=Pepe, F.|title=The HARPS search for southern extra-solar planets. IX. μ Ara, a system with four planets|journal=Astronomy and Astrophysics|volume=462|issue=2|pages=769–776|year=2006|arxiv=astro-ph/0608396|last2= Correia|first2=A. C. M.|last3= Mayor|first3=M.|last4= Tamuz|first4=O.|last5= Benz|first5=W.|last6= Bertaux|first6=J. -L.|last7= Bouchy|first7=F.|last8= Couetdic|first8=J.|last9= Laskar|first9=J.|last10= Lovis|first10=C.|last11= Naef|first11=D.|last12= Queloz|first12=D.|last13= Santos|first13=N. C.|last14= Sivan|first14=J. -P.|last15= Sosnowska|first15=D.|last16= Udry|first16=S.|doi=10.1051/0004-6361:20066194|bibcode = 2007A&A...462..769P |s2cid=119071803}}</ref> [[Astronomy:HD 152079|HD 152079]] is a sunlike star with a jupiter-like planet with an orbital period of 2097 ± 930 days.<ref name="Arriagada2010">{{cite journal | title=Five Long-period Extrasolar Planets in Eccentric orbits from the Magellan Planet Search Program | last1=Arriagada | first1=Pamela | last2=Butler | first2=R. Paul | last3=Minniti | first3=Dante | last4=López-Morales | first4=Mercedes | last5=Shectman | first5=Stephen A. | last6=Adams | first6=Fred C. | last7=Boss | first7=Alan P. | last8=Chambers | first8=John E. | display-authors=1 | journal=The Astrophysical Journal | volume=711 | issue=2 | pages=1229–35 | date=2010 | arxiv=1001.4093 | bibcode=2010ApJ...711.1229A | doi=10.1088/0004-637X/711/2/1229 | s2cid=118682009 }}</ref> [[Astronomy:HD 154672|HD 154672]] is an ageing sunlike star with a [[Astronomy:Hot Jupiter|Hot Jupiter]]. [[Astronomy:HD 154857|HD 154857]] is a sunlike star with one confirmed and one suspected planet. [[Astronomy:HD 156411|HD 156411]] is a star hotter and larger than the sun with a gas giant planet in orbit. [[Astronomy:Gliese 674|Gliese 674]] is a nearby red dwarf star with a planet. [[Astronomy:Gliese 676|Gliese 676]] is a binary star system composed of two red dwarves with four planets.

=== Deep-sky objects ===
[[File:IC 4653 a Familiar Sight.jpg|thumb|IC 4653 galaxy taken by Hubble.<ref>{{cite web |title=A Familiar Sight |url=https://www.spacetelescope.org/images/potw1942a/ |website=www.spacetelescope.org |access-date=23 October 2019 |language=en}}</ref>]]
The northwest corner of Ara is crossed by the [[Astronomy:Galactic plane|galactic plane]] of the [[Astronomy:Milky Way|Milky Way]] and contains several [[Astronomy:Open cluster|open cluster]]s (notably [[Astronomy:NGC 6200|NGC 6200]]) and diffuse nebulae (including the bright cluster/nebula pair [[Astronomy:NGC 6188|NGC 6188]] and [[Astronomy:NGC 6193|NGC 6193]]). The brightest of the [[Astronomy:Globular cluster|globular cluster]]s, sixth magnitude [[Astronomy:NGC 6397|NGC 6397]], lies at a distance of just {{convert|6500|ly|km}}, making it one of the closest globular clusters to the [[Astronomy:Solar System|Solar System]].{{sfn|Dunlop|2005}}

Ara also contains [[Astronomy:Westerlund 1|Westerlund 1]], a [[Astronomy:Super star cluster|super star cluster]] containing itself the possible [[Astronomy:Red supergiant star|red supergiant]] [[Astronomy:Westerlund 1-237|Westerlund 1-237]] and the [[Astronomy:Red supergiant|red supergiant]] [[Astronomy:Westerlund 1-26|Westerlund 1-26]]. The latter is one of the [[Astronomy:List of largest stars|largest stars known]] with an estimate varying between {{solar radius|1,168|link=y}}<ref name=paulo2018>{{cite thesis |doi=10.11606/D.14.2019.tde-12092018-161841 |title=The Red Supergiants in the Supermassive Stellar Cluster Westerlund 1 |year=2019 |last1=Arévalo |first1=Aura |doi-access=free }}</ref> and {{solar radius|2,519|link=y}}.<ref name=thomas>{{Cite journal|arxiv=1209.6427|last1=Fok|first1=Thomas K. T.|title=Maser Observations of Westerlund 1 and Comprehensive Considerations on Maser Properties of Red Supergiants Associated with Massive Clusters|journal=The Astrophysical Journal|volume=760|issue=1|pages=65|last2=Nakashima|first2=Jun-ichi|last3=Yung|first3=Bosco H. K.|last4=Hsia|first4=Chih-Hao|last5=Deguchi|first5=Shuji|year=2012|doi=10.1088/0004-637X/760/1/65|bibcode=2012ApJ...760...65F|s2cid=53393926}}</ref>

Although Ara lies close to the heart of the Milky Way, two spiral galaxies ([[Astronomy:NGC 6215|NGC 6215]] and [[Astronomy:NGC 6221|NGC 6221]]) are visible near star [[Astronomy:Eta Arae|Eta Arae]].{{sfn|Dunlop|2005}}

==== Open clusters ====
* [[Astronomy:NGC 6193|NGC 6193]] is an [[Astronomy:Open cluster|open cluster]] containing approximately 30 stars with an overall magnitude of 5.0 and a size of 0.25 square degrees, about half the size of the full Moon. It is approximately 4200 light-years from Earth. It has one bright member, a double star with a blue-white hued primary of magnitude 5.6 and a secondary of magnitude 6.9. NGC 6193 is surrounded by [[Astronomy:NGC 6188|NGC 6188]], a faint [[Astronomy:Nebula|nebula]] only normally visible in [[Astrophotography|long-exposure photographs]].{{sfn|Ridpath|Tirion|2001|pp=82–83}}
* [[Astronomy:NGC 6200|NGC 6200]]
* [[Astronomy:NGC 6204|NGC 6204]]
* [[Astronomy:NGC 6208|NGC 6208]]
* [[Astronomy:NGC 6250|NGC 6250]]
* NGC 6253
* [[Astronomy:IC 4651|IC 4651]]

==== Globular clusters ====
* [[Astronomy:NGC 6352|NGC 6352]]
* [[Astronomy:NGC 6362|NGC 6362]]
* [[Astronomy:NGC 6397|NGC 6397]] is a [[Astronomy:Globular cluster|globular cluster]] with an overall magnitude of 6.0; it is visible to the naked eye under exceptionally dark skies and is normally visible in binoculars. It is a fairly close globular cluster, at a distance of 10,500 light-years.{{sfn|Ridpath|Tirion|2001|pp=82–83}}

=== Planetary Nebulae ===
* The [[Astronomy:Stingray Nebula|Stingray Nebula]] (Hen 3–1357), the youngest known planetary nebula as of 2010, formed in Ara; the light from its formation was first observable around 1987.
* [[Astronomy:NGC 6326|NGC 6326]].  A planetary nebula that might have a binary system at its center.

== Notes ==
{{Notelist
| notes =

{{efn
| name = pronunciation
| Random House Dictionary
}}

}}

== References ==
{{Reflist}}

== Bibliography ==
* {{cite book
  | last = Dunlop
  | first = Storm
  | date = 2005
  | title = Atlas of the Night Sky
  | url = https://archive.org/details/collinsatlasofni0000dunl
  | url-access = registration
  | publisher = Collins
  | isbn = 978-0-00-717223-8
  }}
* {{cite book
  | last1 = Ridpath
  | first1 = Ian
  | last2 = Tirion
  | first2 = Wil
  | date = 2001
  | title = Stars and Planets Guide
  | publisher = Princeton University Press
  | isbn = 978-0-691-08913-3
  }}
* {{cite book
  | last1 = Ridpath
  | first1 = Ian
  | last2 = Tirion
  | first2 = Wil
  | date = 2007
  | title = Stars and Planets Guide
  | edition = 4th
  | publisher = Princeton University Press
  | isbn = 978-0-691-13556-4
  }}
* {{cite book
  | last = Staal
  | first = Julius D.W.
  | date = 1988
  | title = The New Patterns in the Sky
  | publisher = McDonald and Woodward Publishing Company
  | isbn = 978-0-939923-04-5
  }}
* {{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, VA| isbn = 978-0-939923-78-6 }}

'''Online sources'''
* {{cite web
  | language = zh
  | title = AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 1 日
  | date = 2006
  | url = http://aeea.nmns.edu.tw/2006/0607/ap060701.html
  | access-date = 10 July 2012
  | ref = {{sfnRef|AEEA|2006}}
  }}
* {{cite web
  | last = Ridpath
  | first = Ian
  | title = Ara
  | work = Star Tales
  | url = http://www.ianridpath.com/startales/ara.html
  | access-date = 7 June 2012
  | ref = {{sfnRef|Ridpath, ''Star Tales'' Ara}}
  }}

== External links ==
{{Commons and category|Ara|Ara (constellation)}}
* [http://www.allthesky.com/constellations/norma/ The Deep Photographic Guide to the Constellations: Ara]
* [https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017077 Warburg Institute Iconographic Database (medieval and early modern images of Ara)]

{{Stars of Ara}}
{{Constellations}}
{{Sky|17|23|24|-|53|34|48|10}}

{{DEFAULTSORT:Ara (Constellation)}}
[[Category:Ara (constellation)| ]]
[[Category:Constellations]]
[[Category:Southern constellations]]
[[Category:Constellations listed by Ptolemy]]

{{Sourceattribution|Ara (constellation)}}