Editing Grus (constellation) (section)

===Stars===
{{see also|List of stars in Grus}}
[[Image:Constellation Grus.jpg|thumb|250px|The constellation Grus as it can be seen by the naked eye]]
Keyser and de Houtman assigned twelve stars to the constellation.<ref name=knobel>{{cite journal | title = On Frederick de Houtman's Catalogue of Southern Stars, and the Origin of the Southern Constellations | author= Knobel, Edward B. |journal = [[Monthly Notices of the Royal Astronomical Society]] | volume= 77| issue= 5 | pages=414–32 [430] | bibcode = 1917MNRAS..77..414K |date=1917 | doi=10.1093/mnras/77.5.414| author-link= Edward Knobel | doi-access= free }}</ref> Bayer depicted Grus on his chart, but did not assign its stars [[Bayer designation]]s. French explorer and astronomer [[Nicolas-Louis de Lacaille]] labelled them Alpha to Phi in 1756 with some omissions. In 1879, American astronomer [[Benjamin Apthorp Gould|Benjamin Gould]] added Kappa, Nu, Omicron and Xi, which had all been catalogued by Lacaille but not given Bayer designations. Lacaille considered them too faint, while Gould thought otherwise. Xi Gruis had originally been placed in Microscopium. Conversely, Gould dropped Lacaille's Sigma as he thought it was too dim.<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=360–62}}</ref><!-- cites previous three sentences -->

Grus has several bright stars. Marking the left wing is Alpha Gruis,<ref name=knobel/> a blue-white star of spectral type B6V and [[apparent magnitude]] 1.7, around 101 [[light-year]]s from Earth.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Alpha+Gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Alpha Gruis – High Proper-motion Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 1 December 2013}}</ref> Its traditional name, Alnair, means "the bright one" and refers to its status as the brightest star in Grus (although the Arabians saw it as the brightest star in the Fish's tail, as Grus was then depicted).[http://www.constellationsofwords.com/stars/Alnair.html Alnair] Alnair is around 380 times as [[luminosity|luminous]] and has over 3 times the diameter of the [[Sun]].<ref name="kaleralpha">{{cite web|url=http://stars.astro.illinois.edu/sow/alnair.html |title=Al Nair |last=Kaler|first=James B|author-link=James B. Kaler|work=Stars|publisher=University of Illinois|access-date= 1 December 2013}}</ref> Lying 5 degrees west of Alnair,<ref name="motz"/> denoting the Crane's heart is Beta Gruis<ref name=knobel/> (the proper name is Tiaki<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>), a [[red giant]] of spectral type M5III.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Beta+Gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Beta Gruis – Pulsating Variable Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 1 December 2013}}</ref> It has a diameter of 0.8 [[astronomical unit]]s (AU) (if placed in the Solar System it would extend to the orbit of Venus) located around 170 light-years from Earth. It is a [[variable star]] with a minimum magnitude of 2.3 and a maximum magnitude of 2.0.<ref name="kalerbeta">{{cite web|url=http://stars.astro.illinois.edu/sow/betagru.html |title=Beta Gruis |last=Kaler|first=James B|author-link=James B. Kaler|work=Stars|publisher=University of Illinois|access-date= 1 December 2013}}</ref> An imaginary line drawn from the Great Square of [[Pegasus (constellation)|Pegasus]] through Fomalhaut will lead to Alnair and Beta Gruis.<ref name="moore01"/>

Lying in the northwest corner of the constellation and marking the crane's eye is Gamma Gruis,<ref name="motz">{{cite book|last=Motz|first=Lloyd|author2=Nathanson, Carol|title=The Constellations: An Enthusiast's Guide to the Night Sky|publisher=Aurum Press|location=London, United Kingdom|date=1991|page=370|isbn=978-1-85410-088-7}}</ref> a blue-white [[subgiant]] of spectral type B8III and magnitude 3.0 lying around 211 light-years from Earth.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=GAmma+Gruis&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Gamma Gruis |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 4 December 2013}}</ref> Also known as Al Dhanab,<ref name="IAU-LSN"/> it has finished fusing its core hydrogen and has begun cooling and expanding, which will see it transform into a red giant.<ref name="kalergamma">{{cite web|url=http://stars.astro.illinois.edu/sow/aldhanab.html |title=Al Dhanab |last=Kaler|first=James B|author-link=James B. Kaler|work=Stars|publisher=University of Illinois|access-date= 4 December 2013}}</ref>

There are several [[double star]]s visible to the naked eye in Grus. Forming a triangle with Alnair and Beta, Delta Gruis is an optical double whose components—[[Delta1 Gruis|Delta<sup>1</sup>]] and [[Delta2 Gruis|Delta<sup>2</sup>]]—are separated by 45 arcseconds.<ref name="motz"/> Delta<sup>1</sup> is a [[yellow giant]] of spectral type G7III and magnitude 4.0, 309 light-years from Earth,<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=del1+gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = HR 8556 – Star in double system |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 19 January 2014}}</ref> and may have its own magnitude 12 [[K-type main-sequence star|orange dwarf]] companion.<ref name="kalerdelta">{{cite web|url=http://stars.astro.illinois.edu/sow/deltagru.html |title=Delta Gruis |last=Kaler|first=James B|author-link=James B. Kaler|work=Stars|publisher=University of Illinois|access-date= 26 January 2014}}</ref> Delta<sup>2</sup> is a red giant of spectral type M4.5III and semiregular variable that ranges between magnitudes 3.99 and 4.2,<ref name=AAVSOdel2>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=14810 |title=Delta 2 Gruis |author=Watson, Christopher|date=25 August 2009|work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=18 January 2014}}</ref> located 325 light-years from Earth. It has around 3 times the mass and 135 times the diameter of the Sun.<ref name="kalerdelta"/> Mu Gruis, composed of [[Mu1 Gruis|Mu<sup>1</sup>]] and [[Mu2 Gruis|Mu<sup>2</sup>]], is also an optical double—both stars are yellow giants of spectral type G8III around 2.5 times as massive as the Sun with surface temperatures of around 4900 K.<ref name="kalermu">{{cite web|url=http://stars.astro.illinois.edu/sow/mugru.html |title=Mu Gruis |last=Kaler|first=James B|author-link=James B. Kaler|work=Stars|publisher=University of Illinois|access-date= 26 January 2014}}</ref> Mu<sup>1</sup> is the brighter of the two at magnitude 4.8 located around 275 light-years from Earth,<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HR+8486&submit=SIMBAD+search |title = HR 8486 |work = SIMBAD Astronomical Database |publisher = Centre de Données astronomiques de Strasbourg |access-date = 19 January 2014}}</ref> while Mu<sup>2</sup> the dimmer at magnitude 5.11 lies 265 light-years distant from Earth.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=HR+8488&submit=SIMBAD+search |title = HR 8488 |work = SIMBAD Astronomical Database |publisher = Centre de Données astronomiques de Strasbourg |access-date = 19 January 2014}}</ref> Pi Gruis, an optical double with a variable component, is composed of [[Pi1 Gruis|Pi<sup>1</sup> Gruis]] and [[Pi2 Gruis|Pi<sup>2</sup>]]. Pi<sup>1</sup> is a [[semiregular variable star|semi-regular]] red giant of spectral type S5, ranging from magnitude 5.31 to 7.01 over a period of 191 days,<ref name=AAVSOpi1>{{cite web|url=http://www.aavso.org/vsx/index.php?view=detail.top&oid=14811 |title=Pi 1 Gruis |author =Otero, Sebastian Alberto|date=20 June 2011 |work=AAVSO Website|publisher=American Association of Variable Star Observers|access-date=19 January 2014}}</ref> and is around 532 light-years from Earth.<ref>{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Pi1+Gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Pi1 Gruis – S Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 19 January 2014}}</ref> One of the brightest S-class stars to Earth viewers, it has a companion star of apparent magnitude 10.9 with sunlike properties, being a [[G-type main-sequence star|yellow main sequence star]] of spectral type G0V. The pair make up a likely binary system.<ref>{{cite journal|author1=Sacuto, S. |author2=Jorissen, A. |author3=Cruzalèbes, P. |author4=Chesneau, O. |author5=Ohnaka, K. |author6=Quirrenbach, A. |author7=Lopez, B. |date=2008|title=The close circumstellar environment of the semi-regular S-type star π 1 Gruis|journal=Astronomy & Astrophysics|volume=482|issue=2|pages=561–74| bibcode=2008A&A...482..561S|arxiv = 0803.3077 |doi = 10.1051/0004-6361:20078306 |s2cid=14085392 |url=http://hal.archives-ouvertes.fr/docs/00/26/60/23/PDF/8306.pdf |archive-url=https://web.archive.org/web/20110513023213/http://hal.archives-ouvertes.fr/docs/00/26/60/23/PDF/8306.pdf |archive-date=2011-05-13 |url-status=live}}</ref> Pi<sup>2</sup> is a [[giant star]] of spectral type F3III-IV located around 130 light-years from Earth,<ref>{{cite web |url =http://simbad.u-strasbg.fr/simbad/sim-id?Ident=Pi2+Gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = LTT 8994 – High proper-motion Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 19 January 2014}}</ref> and is often brighter than its companion at magnitude 5.6.{{sfn|Ridpath|Tirion|2001|pp=152–53}} Marking the right wing is [[Theta Gruis]],<ref name=knobel/> yet another double star, lying 5 degrees east of Delta<sup>1</sup> and Delta<sup>2</sup>.<ref name="motz"/>

[[RZ Gruis]] is a binary system of apparent magnitude 12.3 with occasional dimming to 13.4, whose components—a [[white dwarf]] and [[main sequence]] star—are thought to orbit each other roughly every 8.5 to 10 hours. It belongs to the UX Ursae Majoris subgroup of [[cataclysmic variable star]] systems, where material from the donor star is drawn to the white dwarf where it forms an [[accretion disc]] that remains bright and outshines the two component stars. The system is poorly understood,<ref>{{cite journal|author1=Bisol, Alexandra C. |author2=Godon, Patrick |author3=Sion, Edward M. |date=2012|title=Far Ultraviolet Spectroscopy of Three Long Period Nova-Like Variables|journal=Publications of the Astronomical Society of the Pacific|volume=124|issue=912|pages=158–63|bibcode=2012PASP..124..158B|arxiv = 1112.3711 |doi = 10.1086/664464 |s2cid=116536811 }}</ref> though the donor star has been calculated to be of spectral type F5V.<ref>{{cite journal|author1=Stickland, D.J. |author2=Kelly, B.D. |author3=Cooke, J.A. |author4=Coulson, I. |author5=Engelbrecht, C. |author6=Kilkenny, D. |date=1984|title=RZ Gru – A UX UMa 'disc star'|journal=Monthly Notices of the Royal Astronomical Society|volume=206|issue=4 |pages= 819–31|bibcode=1984MNRAS.206..819S|doi=10.1093/mnras/206.4.819|doi-access=free}}</ref> These stars have spectra very similar to novae that have returned to quiescence after outbursts, yet they have not been observed to have erupted themselves. The [[American Association of Variable Star Observers]] recommends watching them for future events.<ref>{{cite web|url=http://www.aavso.org/vsots_uxuma|title=UX Ursae Majoris|last=Malatesta|first=Kerri|date=17 July 2010 |work=Variable Star of the Season|access-date=26 January 2014}}</ref><!-- cites previous two sentences --> [[CE Gruis]] (also known as Grus V-1) is a faint (magnitude 18–21) star system also composed of a white dwarf and donor star; in this case the two are so close they are [[Tidal locking|tidally locked]]. Known as [[Polar (cataclysmic variable star)|polars]], material from the donor star does not form an accretion disc around the white dwarf, but rather streams directly onto it.<ref name="ramsay02">{{cite journal|author1=Ramsay, Gavin |author2=Cropper, Mark |date=2002|title=First X-ray Observations of the Polar CE Gru|journal=Monthly Notices of the Royal Astronomical Society|volume=335|issue=4|pages=918–22|bibcode=2002MNRAS.335..918R|arxiv = astro-ph/0205102 |doi = 10.1046/j.1365-8711.2002.05666.x |doi-access=free |s2cid=8460918 }}</ref>

Six star systems are thought to have planetary systems. [[Tau1 Gruis|Tau<sup>1</sup> Gruis]] is a yellow star of magnitude 6.0 located around 106 light-years away.<ref>{{cite web |url = http://simbad.u-strasbg.fr/simbad/sim-id?Ident=tau1+gru&NbIdent=1&Radius=2&Radius.unit=arcmin&submit=submit+id |title = Tau1 Gruis -- High proper-motion Star |work = SIMBAD Astronomical Database|publisher=Centre de Données astronomiques de Strasbourg |access-date = 11 February 2014}}</ref> It may be a main sequence star or be just beginning to depart from the sequence as it expands and cools. In 2002 the star was found to have a planetary companion.<ref name="Jones2003">{{cite journal | title=An Exoplanet in Orbit around τ1 Gruis | last1=Jones | first1=R. Paul | last2=Butler | first2=Hugh R. A. | last3=Tinney | first3=C. G. | last4=Marcy | first4=Geoffrey W. | last5=Penny | first5=Alan J. | last6=McCarthy | first6=Chris | last7=Carter | first7=Brad D. | journal=Monthly Notices of the Royal Astronomical Society | date=2003 | volume=341 | issue=3 | pages=948–52 | arxiv=astro-ph/0209302 | bibcode=2003MNRAS.341..948J | doi=10.1046/j.1365-8711.2003.06481.x| doi-access=free | s2cid=1575040 }}</ref> [[HD 215456]], [[HD 213240]] and [[WASP-95]] are yellow sunlike stars discovered to have two planets,<ref>{{cite arXiv |last1=Mayor |first1=M. |last2=Marmier |first2=M. |last3=Lovis |first3=C. |last4=Udry |first4=S. |last5=Ségransan |first5=D. |last6=Pepe |first6=F. |last7=Benz |first7=W. |last8=Bertaux |first8=J.-L. |last9=Bouchy |first9=F. |last10=Dumusque |first10=X. |last11=Lo Curto |first11=G. |last12=Mordasini |first12=C. |last13=Queloz |first13=D. |last14=Santos |first14=N.C. |display-authors=1
 |date=2011 |title=The HARPS Search for Southern Extra-solar Planets XXXIV. Occurrence, Mass Distribution and Orbital Properties of Super-Earths and Neptune-mass Planets |eprint=1109.2497 |class=astro-ph.EP}}</ref> a planet and a remote [[red dwarf]],<ref name=mugrauer>{{cite journal | last1=Mugrauer |first1=M. | last2=Neuhäuser | first2=R. | last3=Seifahrt | first3=A. | last4=Mazeh | first4=T. | last5=Guenther | first5=E. | title=Four New Wide Binaries Among Exoplanet Host Stars | journal=[[Astronomy and Astrophysics]] |date=2005 |volume=440 | issue=3 |pages=1051–60 | doi=10.1051/0004-6361:20042297 | bibcode=2005A&A...440.1051M|arxiv = astro-ph/0507101 |s2cid=14065040 }}</ref> and a [[hot Jupiter]], respectively; this last—WASP-95b—completes an orbit round its sun in a mere two days.<ref name="hellier13">{{cite journal|author1=Hellier, Coel |author2=Anderson, D.R. |author3=Collier Cameron, A. |author4=Delrez, L. |author5=Gillon, M. |author6=Jehin, E. |author7=Lendl, M. |author8=Maxted, P.F.L. |author9=Pepe, F. |author10=Pollacco, D. |author11=Queloz, D. |author12=Segransan, D. |author13=Smalley, B. |author14=Smith, A.M.S. |author15=Southworth, J. |author16=Triaud, A.H.M.J. |author17=Udry, S. |author18=West, R.G. |date=2014|title=Transiting Hot Jupiters from WASP-South, Euler and TRAPPIST: WASP-95b to WASP-101b|bibcode=2014MNRAS.440.1982H|arxiv=1310.5630|doi=10.1093/mnras/stu410|journal=Monthly Notices of the Royal Astronomical Society |volume=440 |issue=3 |pages=1982–92|doi-access=free |s2cid=54977201 }}</ref> [[Gliese 832]] is a red dwarf of spectral type M1.5V and apparent magnitude 8.66 located only 16.1 light-years distant; hence it is one of the nearest stars to the Solar System. A [[Jupiter]]-like planet—[[Gliese 832 b]]—orbiting the red dwarf over a period of 9.4±0.4 years was discovered in 2008.<ref name="bailey08">{{cite journal |last1=Bailey |first1=J. |last2=Butler |first2=R.P. |last3=Tinney |first3=C.G. |last4=Jones |first4=H.R.A. |last5=O'Toole |first5=S. |last6=Carter |first6=B.D. |last7=Marcy |first7=G. W. |year=2009|title=A Jupiter-like Planet Orbiting the Nearby M Dwarf GJ832 |journal=[[The Astrophysical Journal]] |volume=690 |issue=1 |pages=743–47 |arxiv=0809.0172 |bibcode=2009ApJ...690..743B |doi=10.1088/0004-637X/690/1/743|s2cid=17172233 }}</ref><!-- cites 2 previous sentences --> [[WISE 2220−3628]] is a [[brown dwarf]] of spectral type Y, and hence one of the coolest star-like objects known. It has been calculated as being around 26 light-years distant from Earth.<ref name="Kirkpatrick2012">{{cite journal |author-link=J. Davy Kirkpatrick |last1=Kirkpatrick |first1=J. Davy |last2=Gelino |first2=Christopher R. |last3=Cushing |first3=Michael C. |last4=Mace | first4=Gregory N. |last5=Griffith |first5=Roger L. |last6=Skrutskie |first6=Michael F. |last7=Marsh |first7=Kenneth A. |last8=Wright |first8=Edward L. |last9=Eisenhardt |first9=Peter R. |last10=McLean |first10=Ian S. |last11=Mainzer | first11=Amy K. |last12=Burgasser |first12=Adam J. |last13=Tinney |first13=Chris G. |last14=Parker |first14=Stephen |last15=Salter |first15=Graeme |title=Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function |year=2012 |journal=[[The Astrophysical Journal]] |volume=753 |issue=2 |pages=156 |arxiv=1205.2122 |doi=10.1088/0004-637X/753/2/156 |bibcode=2012ApJ...753..156K |s2cid=119279752 }}</ref>

In July 2019, astronomers reported finding a star, [[S5-HVS1]], traveling {{convert|1755|km/s|mph|abbr=on}}, faster that any other star detected so far. The star is in the Grus constellation in the southern sky, and about 29,000 light-years from Earth, and may have been propelled out of the [[Milky Way]] [[galaxy]] after interacting with [[Sagittarius A*]], the [[supermassive black hole]] at the center of the galaxy.<ref name="NYT-20191114">{{cite news |last=Overbye |first=Dennis |author-link=Dennis Overbye |title=A Black Hole Threw a Star Out of the Milky Way Galaxy - So long, S5-HVS1, we hardly knew you. |url=https://www.nytimes.com/2019/11/14/science/stars-black-hole-milky-way.html |archive-url=https://ghostarchive.org/archive/20220102/https://www.nytimes.com/2019/11/14/science/stars-black-hole-milky-way.html |archive-date=2022-01-02 |url-access=limited |url-status=live |date=14 November 2019 |work=[[The New York Times]] |access-date=18 November 2019 }}{{cbignore}}</ref><ref name="MNRAS-20191109">{{cite journal |author=Koposov, Sergey E. |display-authors=et al. |title= Discovery of a nearby 1700 km/s star ejected from the Milky Way by Sgr A*|journal=Monthly Notices of the Royal Astronomical Society |date=11 November 2019 |arxiv=1907.11725 |doi=10.1093/mnras/stz3081 |doi-access=free |s2cid=198968336 }}</ref><ref name="SA-20190731">{{cite news |last=Starr |first=Michelle |title=Bizarre Star Found Hurtling Out of Our Galaxy Centre Is Fastest of Its Kind Ever Seen |url=https://www.sciencealert.com/our-bossy-black-hole-kicked-out-a-star-and-it-s-shooting-through-the-galaxy-insanely-fast |date=31 July 2019 |work=ScienceAlert.com |access-date=18 November 2019 }}</ref><ref name="NA-20191113">{{cite news |last=Irving |first=Michael |title=Fastest star ever found is being flicked out of the Milky Way |url=https://newatlas.com/space/fastest-star-hypervelocity-ejected-milky-way/ |date=13 November 2019 |work=NewAtlas.com |access-date=18 November 2019 }}</ref>