Editing Piscis Austrinus (section)

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

===Stars===
{{See also|List of stars in Piscis Austrinus}}
Ancient astronomers counted twelve stars as belonging to Piscis Austrinus, though one was later incorporated into nearby Grus as [[Gamma Gruis]].<ref name=condos97/> Other stars became part of Microscopium.<ref name=ridpathPsA/> Bayer used the [[Greek letters]] [[alpha]] through [[Mu (letter)|mu]] to label the most prominent stars in the constellation. Ptolemy had catalogued Fomalhaut (Alpha Piscis Austrini) as belonging to both this constellation and Aquarius. Lacaille redrew the constellation as it was poorly visible from Europe, adding [[Pi (letter)|pi]], and relabelling [[gamma]], [[Delta (letter)|delta]] and [[epsilon]] as epsilon, [[eta]] and gamma, respectively. However, Baily and Gould did not uphold these changes as Bayer's original chart was fairly accurate. Bode added [[tau]] and [[upsilon]]. Flamsteed gave 24 stars [[Flamsteed designation]]s, though the first four numbered became part of Microscopium.<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=251–54, 457–58}}</ref> Within the constellation's borders, there are 47 stars brighter than or equal to [[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 name=bortle>{{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]]|publisher=Sky Publishing Corporation|access-date=25 November 2018}}</ref>}}<ref name=tirionconst/>

Traditionally representing the mouth of the fish, Fomalhaut is the brightest star in the constellation and the [[List of brightest stars|18th-brightest star]] in the night sky, with an apparent magnitude of 1.16. Located 25.13 ± 0.09 [[light-year]]s away, it is a white [[main-sequence star]] that is 1.92 ± 0.02 times as massive and 16.63 ± 0.48 as luminous as the Sun.<ref name=age_mam>{{Cite journal | last1=Mamajek | first1=Eric E. | title=On the Age and Binarity of Fomalhaut | journal=Astrophysical Journal Letters | volume=754 | issue=2 |date=August 2012 | pages=L20 | doi=10.1088/2041-8205/754/2/L20 | arxiv=1206.6353| bibcode=2012ApJ...754L..20M | s2cid=119191190 }}</ref> Its companion [[Fomalhaut b]] was thought to be the first [[extrasolar planet]] ever detected by a visible light image, thanks to the [[Hubble Space Telescope]], but infrared observations have since retracted this claim: it is instead a spherical cloud of dust. [[TW Piscis Austrini]] can be seen close by and is possibly associated with Fomalhaut as it lies within a light-year of it. Of magnitude 6.5, it is a BY Draconis variable.<ref name=moore11>{{cite book|last=Moore|first=Patrick|title=Patrick Moore's Data Book of Astronomy|publisher=[[Cambridge University Press]]|date=2011|page=472|isbn=978-0521899352|url=https://books.google.com/books?id=2FNfjWKBZx8C&q=Piscis+Austrinus}}</ref>

The second-brightest star in the constellation,<ref name=kalerbeta/> [[Epsilon Piscis Austrini]] is a blue-white star of magnitude +4.17. Located 400 ± 20 light-years distant,<ref name=Gaia-DR2epsilon>{{cite DR2|6622561673163632768}}</ref> it is a blue-white main-sequence star 4.10 ± 0.19 times as massive as the Sun, and around 661 times as luminous.<ref name=zorec2012>{{cite journal | title=Rotational velocities of A-type stars. IV. Evolution of rotational velocities | journal=Astronomy & Astrophysics | volume=537 | pages=A120 | year=2012 | last1=Zorec | first1=J. | last2=Royer | first2=F. | doi=10.1051/0004-6361/201117691 | bibcode=2012A&A...537A.120Z | arxiv=1201.2052 | s2cid=55586789 }}</ref>

[[Beta Piscis Austrini|Beta]], [[Delta Piscis Austrini|Delta]] and [[Zeta Piscis Austrini|Zeta]] constitute the ''Tien Kang'' ("heavenly rope") in [[China]].<ref>{{cite web| url = https://penelope.uchicago.edu/Thayer/E/Gazetteer/Topics/astronomy/_Texts/secondary/ALLSTA/Piscis_Australis*.html| title = Richard Hinckley Allen: Star Names — Their Lore and Meaning: Piscis Australis, the Southern Fish}}</ref> Beta is a white main-sequence star of apparent magnitude 4.29 that is of similar size and luminosity to Fomalhaut but five times as remote,<ref name=kalerbeta>{{Cite web |url=http://stars.astro.illinois.edu/sow/betapsa.html |title=Beta PsA |first=Jim |last=Kaler |date=12 November 2009 |access-date=17 March 2018}}</ref> at around 143 ± 1 light-years distant from Earth.<ref name="vanLeeuwen2007">{{cite journal|first=F.|last=van Leeuwen|title=Validation of the New Hipparcos Reduction|journal=[[Astronomy and Astrophysics]]|volume=474|issue=2|pages=653–64|date=2007|bibcode=2007A&A...474..653V|doi=10.1051/0004-6361:20078357|arxiv=0708.1752|s2cid=18759600}}</ref> Delta Piscis Austrini is a double star with components of magnitude 4.2 and 9.2.<ref name=moore11/> The brighter is a yellow giant of spectral type G8 III.<ref name=houk1979>{{cite book | title=Michigan catalogue of two-dimensional spectral types for the HD stars | volume=3 | last1=Houk | first1=Nancy | location=Ann Arbor, Michigan | publisher=Department of Astronomy, University of Michigan | date=1979 | bibcode=1982mcts.book.....H }}</ref> It is a [[red clump]] star that is burning helium in its core.<ref name=Liu2007>{{cite journal | last1=Liu | first1=Y. J. | last2=Zhao | first2=G. | last3=Shi | first3=J. R. | last4=Pietrzyński | first4=G. | last5=Gieren | first5=W. | title=The abundances of nearby red clump giants | journal=Monthly Notices of the Royal Astronomical Society | volume=382 | issue=2 | pages=553–66 | date=2007 | bibcode=2007MNRAS.382..553L | doi=10.1111/j.1365-2966.2007.11852.x | doi-access=free }}</ref> It is 172 ± 2 light-years distant from Earth.<ref name=Gaia-DR2delta>{{cite DR2|6603237069110536960}}</ref> Zeta Piscis Austrini is an orange giant star of spectral type K1III that is located 413 ± 2 light-years distant from Earth.<ref name=Gaia-DR2zeta>{{cite DR2|6622197425577482752}}</ref> It is a suspected variable star.<ref name=Demartino1996>{{cite journal| last1=Demartino | first1=Robert | last2=Kocyla | first2=Dennis | last3=Predom | first3=Christopher | last4=Wetherbee | first4=Edward | title=Accurate Positions Of Suspected Variable Stars Near The South Galactic Pole | journal=Information Bulletin on Variable Stars | volume=4322 | page=1 | date=1996 | bibcode=1996IBVS.4322....1D }}</ref>

[[S Piscis Austrini]] is a long-period Mira-type variable red giant which ranges between magnitude 8.0 and 14.5 over a period of 271.7 days, and [[V Piscis Austrini]] is a semi-regular variable ranging between magnitudes 8.0 and 9.0 over 148 days.<ref name=moore11/>

Lacaille 9352 is a faint [[red dwarf]] star of spectral type M0.5V that is just under half the Sun's diameter and mass.<ref name="rabus">{{cite journal |doi=10.1093/mnras/sty3430 |title=A discontinuity in the Teff–radius relation of M-dwarfs |journal=Monthly Notices of the Royal Astronomical Society |volume=484 |issue=2 |pages=2674–2683 |year=2019 |last1=Rabus |first1=Markus |last2=Lachaume |first2=Régis |last3=Jordán |first3=Andrés |last4=Brahm |first4=Rafael |last5=Boyajian |first5=Tabetha |last6=Von Braun |first6=Kaspar |last7=Espinoza |first7=Néstor |last8=Berger |first8=Jean-Philippe |last9=Le Bouquin |first9=Jean-Baptiste |last10=Absil |first10=Olivier |doi-access=free |arxiv=1901.08077 |bibcode=2019MNRAS.484.2674R |s2cid=119189542 }}</ref> A mere 10.74 light-years away, it is too dim to be seen with the naked eye at magnitude 7.34. In June 2020 two [[super-Earth]] planets were discovered via [[radial velocity method]].

Exoplanets have been discovered in five other star systems in the constellation. [[HD 205739]] is a yellow-white main-sequence star of spectral type F7 V that has a planet around 1.37 times as massive as Jupiter orbiting it with a period of 279 days, and a suggestion of a second planet.<ref name="LopezMorales2008">{{cite journal | title=Two Jupiter-Mass Planets Orbiting HD 154672 and HD 205739 | last1=López-Morales | first1=Mercedes | last2=Butler | first2=R. Paul | last3=Fischer | first3=Debra A. | last4=Minniti | first4=Dante | last5=Shectman | first5=Stephen A. | last6=Takeda | first6=Genya | last7=Adams | first7=Fred C. | last8=Wright | first8=Jason T. | last9=Arriagada | first9=Pamela | journal=The Astronomical Journal | volume=136 | issue=5 | pages=1901–1905 | date=2008 | arxiv=0809.1037 | bibcode=2008AJ....136.1901L | doi=10.1088/0004-6256/136/5/1901 | s2cid=119242543 }}</ref> [[HD 216770]] is an orange dwarf accompanied by a Jupiter-like planet every 118 days.<ref name="Mayor2004">{{cite journal | title=The CORALIE survey for southern extra-solar planets XII. Orbital solutions for 16 extra-solar planets discovered with CORALIE | last1=Mayor | first1=M. | last2=Udry | first2=S. | last3=Naef | first3=D. | last4=Pepe | first4=F. | last5=Queloz | first5=D. | last6=Santos | first6=N. C. | last7=Burnet | first7=M. | journal=Astronomy and Astrophysics | volume=415 | issue=1 | pages=391–402 | year=2004 | arxiv=astro-ph/0310316 | bibcode=2004A&A...415..391M | doi=10.1051/0004-6361:20034250 | s2cid=5233877 }}</ref> [[HD 207832]] is a star of spectral type G5V with a diameter and mass about 90% of that of the Sun, and around 77% of its luminosity. Two gas giant planets with masses around 56% and 73% that of Jupiter were discovered in 2012 via the radial velocity method. With orbits of 162 and 1156 days, they average around 0.57 and 2.11 astronomical units away from their star.<ref>{{cite journal |last1=Haghighipour |first1=Nader |last2=Butler |first2=R. Paul |last3=Rivera |first3=Eugenio J. |last4=Henry |first4=Gregory W. |last5=Vogt |first5=Steven S. |title=The Lick-Carnegie Survey: A new two-planet system around the star HD 207832 |journal=The Astrophysical Journal |date=  2012 |volume=756 |issue=1 |pages=91 |doi=10.1088/0004-637X/756/1/91|arxiv=1207.2806 |bibcode=2012ApJ...756...91H |s2cid=1137984 }}</ref>

[[WASP-112]] and [[WASP-124]] are two sun-like stars that have planets discovered by transit.

===Deep sky objects===
[[NGC 7172]], [[NGC 7174]] and [[NGC 7314]] are three galaxies of magnitudes 11.9, 12.5 and 10.9, respectively.<ref name=moore11/> [[NGC 7259]] is another [[spiral galaxy]], which hosted a [[supernova]]—[[SN 2009ip]]—in 2009.

At [[redshift]] z = 0.116, the [[BL Lacertae object]] [[PKS 2155-304]] is one of the brightest [[blazar]]s in the sky.<ref>{{Cite journal|author1=Aharonian, F. |author2=Akhperjanian, A. G. |author3=Bazer-Bachi, A. R. |author4=Behera, B. |author5=Beilicke, M. |author6=Benbow, W. |author7=Berge, D. |author8=Bernlöhr, K. |author9=Boisson, C. |author10=Bolz, O. |author11=Borrel, V. |author12=Boutelier, T. |author13=Braun, I. |author14=Brion, E. |author15=Brown, A. M. |author16=Bühler, R. |author17=Büsching, I. |author18=Bulik, T. |author19=Carrigan, S. |author20=Chadwick, P. M. |author21=Clapson, A. C. |author22=Chounet, L.-M. |author23=Coignet, G. |author24=Cornils, R. |author25=Costamante, L. |author26=Degrange, B. |author27=Dickinson, H. J. |author28=Djannati-Ataï, A. |author29=Domainko, W. |author30=Drury, L. O'C. |author31=Dubus, G. |author32=Dyks, J. |author33=Egberts, K. |author34=Emmanoulopoulos, D. |author35=Espigat, P. |author36=Farnier, C. |author37=Feinstein, F. |author38=Fiasson, A. |author39=Förster, A. |author40=Fontaine, G. |author41=Funk, Seb. |author42=Funk, S. |author43=Füßling, M. |author44=Gallant, Y. A. |author45=Giebels, B. |author46=Glicenstein, J. F. |author47=Glück, B. |author48=Goret, P. |author49=Hadjichristidis, C. |author50=Hauser, D. |author51=Hauser, M. |author52=Heinzelmann, G. |author53=Henri, G. |author54=Hermann, G. |author55=Hinton, J. A. |author56=Hoffmann, A. |author57=Hofmann, W. |author58=Holleran, M. |author59=Hoppe, S. |author60=Horns, D. |author61=Jacholkowska, A. |author62=de Jager, O. C. |author63=Kendziorra, E. |author64=Kerschhaggl, M. |author65=Khélifi, B. |author66=Komin, Nu. |author67=Kosack, K. |author68=Lamanna, G. |author69=Latham, I. J. |author70=Le Gallou, R. |author71=Lemière, A. |author72=Lemoine-Goumard, M. |author73=Lenain, J.-P. |author74=Lohse, T. |author75=Martin, J. M. |author76=Martineau-Huynh, O. |author77=Marcowith, A. |author78=Masterson, C. |author79=Maurin, G. |author80=McComb, T. J. L. |author81=Moderski, R. |author82=Moulin, E. |author83=de Naurois, M. |author84=Nedbal, D. |author85=Nolan, S. J. |author86=Olive, J.-P. |author87=Orford, K. J. |author88=Osborne, J. L. |author89=Ostrowski, M. |author90=Panter, M. |author91=Pedaletti, G. |author92=Pelletier, G. |author93=Petrucci, P.-O. |author94=Pita, S. |author95=Pühlhofer, G. |author96=Punch, M. |author97=Ranchon, S. |author98=Raubenheimer, B. C. |author99=Raue, M. |display-authors=1 |author100=Rayner, S. M. |author101=Renaud, M. |author102=Ripken, J. |author103=Rob, L. |author104=Rolland, L. |author105=Rosier-Lees, S. |author106=Rowell, G. |author107=Rudak, B. |author108=Ruppel, J. |author109=Sahakian, V. |author110=Santangelo, A. |author111=Saugé, L. |author112=Schlenker, S. |author113=Schlickeiser, R. |author114=Schröder, R. |author115=Schwanke, U. |author116=Schwarzburg, S. |author117=Schwemmer, S. |author118=Shalchi, A. |author119=Sol, H. |author120=Spangler, D. |author121=Stawarz, Ł. |author122=Steenkamp, R. |author123=Stegmann, C. |author124=Superina, G. |author125=Tam, P. H. |author126=Tavernet, J.-P. |author127=Terrier, R. |author128=van Eldik, C. |author129=Vasileiadis, G. |author130=Venter, C. |author131=Vialle, J. P. |author132=Vincent, P. |author133=Vivier, M. |author134=Völk, H. J. |author135=Volpe, F. |author136=Wagner, S. J. |author137=Ward, M. |author138=Zdziarski, A. A. |title=An Exceptional VHE Gamma-Ray Flare of PKS 2155-304|journal=The Astrophysical Journal|volume=664|issue=2|pages=L71–L78|arxiv=0706.0797|year=2007|doi=10.1086/520635|bibcode = 2007ApJ...664L..71A |s2cid=119319369}}</ref>