Editing Delphinus

{{Short description|Constellation in the northern celestial hemisphere}}
{{About|the constellation}}
{{Infobox constellation
| name = Delphinus
| abbreviation = Del
| genitive = Delphini
| pronounce = {{IPAc-en|d|ɛ|l|ˈ|f|aɪ|n|ə|s}} ''Delfínus'', genitive {{IPAc-en|d|ɛ|l|ˈ|f|aɪ|n|aɪ}} 
| symbolism = dolphin
| RA = {{RA|20|14|14.1594}} to {{RA|21|08|59.6073}}<ref name="boundary">{{Cite journal | title=Delphinus, Constellation Boundary | journal=The Constellations | publisher=International Astronomical Union | url=https://www.iau.org/public/themes/constellations/#del | access-date=15 July 2020 }}</ref>
| dec= {{DEC|+2.4021468}} to {{DEC|+20.9399471}}<ref name="boundary" />
| family = [[Heavenly Waters (astronomy)|Heavenly Waters]]
| quadrant = NQ4
| areatotal = 189
| arearank = 69th 
| numbermainstars = 5
| numberbfstars = 19
| numberstarsplanets = 6
| numberbrightstars = 0
| numbernearbystars = 2
| brighteststarname = [[Rotanev]] (β Del)
| starmagnitude = 3.63
| neareststarname = [[HU Delphini|HU Del]]
| stardistancely = 29.01
| stardistancepc = 8.89
| numbermessierobjects = 0
| meteorshowers = None
| bordering = [[Vulpecula]]<br />[[Sagitta]]<br />[[Aquila (constellation)|Aquila]]<br />[[Aquarius (constellation)|Aquarius]]<br />[[Equuleus]]<br />[[Pegasus (constellation)|Pegasus]]
| latmax = [[North Pole|90]]
| latmin = [[69th parallel south|69]]
| month = September
| notes=}}

'''Delphinus''' is a small [[constellation]] in the [[Northern Celestial Hemisphere]], close to the [[celestial equator]]. Its name  is the [[Latin]] version for the [[Greek language|Greek]] word for [[dolphin]] ({{lang|el|δελφίς}}). It is one of the 48 constellations listed by the 2nd-century astronomer [[Ptolemy]], and remains one of the 88 modern constellations recognized by the [[International Astronomical Union]]. It is one of the smaller constellations, ranked 69th in size. Delphinus' five brightest stars form a distinctive [[Asterism (astronomy)|asterism]] symbolizing a dolphin with four stars representing the body and one the tail. It is bordered (clockwise from north) by [[Vulpecula]], [[Sagitta]], [[Aquila (constellation)|Aquila]], [[Aquarius (constellation)|Aquarius]], [[Equuleus]] and [[Pegasus (constellation)|Pegasus]].

Delphinus is a faint constellation with only two stars brighter than an [[apparent magnitude]] of 4, [[Beta Delphini]] (Rotanev) at magnitude 3.6 and [[Alpha Delphini]] (Sualocin) at magnitude 3.8.

==Mythology==
[[File:Sidney Hall - Urania's Mirror - Delphinus, Sagitta, Aquila, and Antinous.jpg|upright=0.9|thumb|left|Delphinus is depicted on the left of this card from ''[[Urania's Mirror]]'' (1825)]]
Delphinus is associated with two stories from [[Greek mythology]].

According to myth, the first Greek god [[Poseidon]] wanted to marry [[Amphitrite]], a beautiful [[nereid]]. However, wanting to protect her virginity, she fled to the Atlas Mountains. Her suitor then sent out several searchers, among them a certain Delphinus. Delphinus accidentally stumbled upon her and persuaded Amphitrite to accept Poseidon's wooing. Out of gratitude, the god placed the image of a dolphin among the stars.<ref>{{Cite web|url=http://www.theoi.com/Text/HyginusAstronomica.html#17|title=HYGINUS, ASTRONOMICA 2.1-17|last=Pseudo-Hyginus|website=Theoi Classical Texts Library|access-date=June 26, 2017}}</ref>

The second story tells of the Greek poet [[Arion]] of [[Lesbos]] (7th century BC), who a dolphin saved.{{sfn|Ridpath|Tirion|2017|pp=140-141}} He was a court musician at the palace of Periander, ruler of Corinth. Arion had amassed a fortune during his travels to Sicily and Italy. On his way home from [[Taranto|Tarentum]], his wealth caused the crew of his ship to conspire against him. Threatened with death, Arion asked to be granted a last wish, which the crew granted: he wanted to sing a dirge.<ref>Herodotus, ''Histories'' I.23-24;<br />''also'' [[Aulus Gellius]], ''Noctes Atticae'' XVI.19; [[Plutarch]], ''Conv. sept. sap.'' 160–62; [[Shakespeare]], ''Twelfth Night'' (Act I, Sc 2, line 16)</ref> This he did, and while doing so, flung himself into the sea.  There, he was rescued by a dolphin which had been charmed by Arion's music. The dolphin carried Arion to the coast of Greece and left.<ref name="S&T">{{cite journal |title = The Celestial Dolphin |last = Schaaf |first = Fred |page = 47 |journal = Sky and Telescope |date = September 2012|volume = 124 |issue = 3 |bibcode = 2012S&T...124c..47S }}</ref>

===In non-Western astronomy===
In [[Chinese astronomy]], the stars of Delphinus are located within ''[[Black Tortoise (Chinese constellation)|the Black Tortoise of the North]]'' (北方玄武, ''Běi Fāng Xuán Wǔ'').<ref>{{in lang|zh}}  [http://aeea.nmns.edu.tw/2006/0607/ap060704.html AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 4 日]</ref>

In [[Polynesia]], two cultures recognized Delphinus as a constellation. In [[Pukapuka]], it was called ''Te Toloa'' and in the [[Tuamotus]], it was called ''Te Uru-o-tiki''.{{sfn|Makemson|1941|p=283}}

In [[Hindu astrology]], the Delphinus corresponds to the [[Nakshatra]], or lunar mansion, of [[Dhanishta]].

==Characteristics==
Delphinus is bordered by [[Vulpecula]] to the north, [[Sagitta]] to the northwest, [[Aquila (constellation)|Aquila]] to the west and southwest, [[Aquarius (constellation)|Aquarius]] to the southeast, [[Equuleus]] to the east and [[Pegasus (constellation)|Pegasus]] to the east.<ref name="boundary" /> Covering 188.5&nbsp;square degrees, corresponding to 0.457% of the sky, it ranks 69th of the 88 constellations in size.<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= 4 March 2016| author-link=Ian Ridpath }}</ref> The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is "Del".<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 (US magazine)|Popular Astronomy]] | volume=30 | page=469 | bibcode=1922PA.....30..469R | date=1922}}</ref> The official constellation boundaries, as set by [[Eugène Joseph Delporte|Eugène Delporte]] in 1930, are defined by a polygon of 14 segments. In the [[equatorial coordinate system]], the [[right ascension]] coordinates of these borders lie between {{RA|20|14|14.1594}} and {{RA|21|08|59.6073}}, while the [[declination]] coordinates are between {{DEC|+2.4021468}} and {{DEC|+20.9399471}}.<ref name="boundary" /> The whole constellation is visible to observers north of latitude [[69th parallel south|69°S]].<ref name=tirionconst/>{{efn|1=While parts of the constellation rise above the horizon to observers between 69°S and [[87th parallel south|87°S]], stars within a few degrees of the horizon are practically unobservable.<ref name=tirionconst/>}}

==Features==
[[Image:DelphinusCC.jpg|thumb|left|upright=0.8|The constellation Delphinus as it can be seen by the naked eye]]

[[Image:Del 20191202.jpg|thumb|right|Contrast and color enhanced photograph of Delphinus]]

===Stars===
{{See also|List of stars in Delphinus}}
Delphinus has two stars above fourth [[apparent magnitude|(apparent) magnitude]]; its brightest star is of magnitude 3.6. The main [[asterism (astronomy)|asterism]] in Delphinus is Job's Coffin, nearly a 45°-apex [[lozenge (shape)|lozenge]] or diamond of the four brightest stars: Alpha, Beta, Gamma, and Delta Delphini. Delphinus is in a rich Milky Way star field. Alpha and Beta Delphini have 19th-century names Sualocin and Rotanev, read backwards: Nicolaus Venator, the Latinized name of a [[Palermo Astronomical Observatory|Palermo Observatory]] director, [[Niccolò Cacciatore]] (d. 1841).{{sfn|Ridpath|Tirion|2017|pp=140-141}}

[[Alpha Delphini]] is a blue-white hued [[main sequence]] star of magnitude 3.8,<ref name=oja>{{cite journal|bibcode=1991A&AS...89..415O|title=UBV photometry of stars whose positions are accurately known. VI|journal=Astronomy and Astrophysics Supplement Series|volume=89|pages=415|last1=Oja|first1=T.|year=1991}}</ref> 241 light-years from Earth. It is a spectroscopic binary.<ref name=malkov>{{cite journal|bibcode=2012A&A...546A..69M|title=Dynamical masses of a selected sample of orbital binaries|journal=Astronomy & Astrophysics|volume=546|pages=A69|last1=Malkov|first1=O. Yu.|last2=Tamazian|first2=V. S.|last3=Docobo|first3=J. A.|last4=Chulkov|first4=D. A.|year=2012|doi=10.1051/0004-6361/201219774|doi-access=free}}</ref> It is officially named Sualocin.<ref name=Kunitzsch>{{cite book
  |last1=Kunitzsch |first1=Paul
  |last2=Smart |first2=Tim
  |date = 2006  |edition = 2nd rev.
  |title = A Dictionary of Modern Star Names: A Short Guide to 254 Star Names and Their Derivations
  |publisher = Sky Pub |location = Cambridge, Massachusetts
  |isbn = 978-1-931559-44-7
}}</ref><ref name=Sualocin>{{cite web | url=https://www.iau.org/public/themes/naming_stars/ | title=Naming Stars |publisher=IAU.org |accessdate=16 December 2017}}</ref> The star has an absolute magnitude of -0.4.<ref name=mv>{{cite journal|bibcode=1998A&A...330..619J|title=The absolute magnitude of the early type MK standards from HIPPARCOS parallaxes|journal=Astronomy and Astrophysics|volume=330|pages=619|last1=Jaschek|first1=C.|last2=Gomez|first2=A. E.|year=1998}}</ref>

[[Beta Delphini]] is officially called Rotanev.<ref name=Kunitzsch/> It was found to be a binary star in 1873.<ref name=burnham1978>{{citation | first1=Robert | last1=Burnham | title=Burnham's celestial handbook: an observer's guide to the universe beyond the Solar System | volume=2 | series=Dover Books on Astronomy | edition=2nd | publisher=[[Courier Dover Publications]] | year=1978 | isbn=0-486-23568-8 | page=820 | url=https://books.google.com/books?id=wB9uZ9lH5bgC&pg=PA820 }}</ref> The gap between its close [[binary star|binary]] stars is visible from large amateur telescopes. To the unaided eye, it appears to be a white star of magnitude 3.6.<ref name=aj138_5_1354>{{citation | display-authors=1 | last1=Davidson | first1=James W. Jr. | last2=Baptista | first2=Brian J. | last3=Horch | first3=Elliott P. | last4=Franz | first4=Otto | last5=van Altena | first5=William F. | title=A Photometric Analysis of Seventeen Binary Stars Using Speckle Imaging | journal=The Astronomical Journal | volume=138 | issue=5 | pages=1354–1364 |date=November 2009 | doi=10.1088/0004-6256/138/5/1354 | bibcode=2009AJ....138.1354D | s2cid=122194357 | doi-access=free }}</ref><ref name=burnham1978 /> It has a period of 27 years and is 97 light-years from Earth.

[[Gamma Delphini]] is a celebrated binary star among amateur astronomers. The primary is orange-gold of magnitude 4.3; the secondary is a light yellow star of magnitude 5.1. The pair forms a true binary with an estimated orbital period of over 3,000 years. 125 light-years away, the two components are visible in a small amateur telescope.{{sfn|Ridpath|Tirion|2017|pp=140-141}} The secondary, also described as green, is 10 arcseconds from the primary. [[Struve 2725]], called the "Ghost Double", is a pair that appears similar but dimmer. Its components of magnitudes 7.6 and 8.4 are separated by 6 arcseconds and are 15 arcminutes from Gamma Delphini itself.<ref name="S&T"/> An unconfirmed exoplanet with a minimum mass of 0.7 Jupiter masses may orbit one of the stars.<ref name=Irwin_et_al_1999>{{citation
 | title=A Program for the Analysis of Long-Period Binaries: The Case of γ Delphini
 | display-authors=1 | last1=Irwin | first1=A. W.
 | last2=Vandenberg | first2=D. A. | last3=Larson | first3=A. M.
 | work=Precise Stellar Radial Velocities. IAU Colloquium 170
 | series=ASP Conference Series #185
 | editor1-first=J. B. | editor1-last=Hearnshaw
 | editor2-first=C. D. | editor2-last=Scarfe
 | isbn=1-58381-011-0 | date=1999 | volume=185 | page=297
 | bibcode=1999ASPC..185..297I }}</ref><ref name="Wittemeyer et al.">{{cite journal
 | display-authors=1 | last1=Wittemeyer
 | last2=Endl | first2=Michael | last3=Cochran | first3=William D.
 | last4=Hatzes | first4=Artie P. | last5=Walker | first5=G. A. H.
 | last6=Yang | first6=S. L. S. | last7=Paulson | first7=Diane B.
 | title=Detection Limits from the McDonald Observatory Planet Search Program
 | journal=[[The Astronomical Journal]]
 | volume=132 | issue=1 | pages=177–188 | date=2006
 | bibcode=2006AJ....132..177W | arxiv=astro-ph/0604171
 | doi=10.1086/504942 | s2cid=16755455
 }}</ref>

[[Delta Delphini]] is a type [[A-type main sequence star|A-type star]]<ref name=gray2001>{{citation
 | last1=Gray | first1=R. O.
 | last2=Napier | first2=M. G.
 | last3=Winkler | first3=L. I.
 | title=The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars
 | journal=The Astronomical Journal
 | volume=121 | issue=4 | pages=2148–2158
 | date=April 2001 | doi=10.1086/319956
 | bibcode=2001AJ....121.2148G | postscript=.
| doi-access=free}}</ref> of magnitude 4.43.<ref name=Chang2013>{{citation
 | title=Statistical Properties of Galactic δ Scuti Stars: Revisited
 | last1=Chang | first1=S.-W. | last2=Protopapas | first2=P.
 | last3=Kim | first3=D.-W. | last4=Byun | first4=Y.-I.
 | journal=The Astronomical Journal | display-authors=1
 | volume=145 | issue=5 | date=2013
 | bibcode=2013AJ....145..132C | doi=10.1088/0004-6256/145/5/132
 | arxiv=1303.1031 | postscript=. | page=132| s2cid=118900730 }}</ref> It is a spectroscopic binary, and both stars are [[Delta Scuti variable]]s.<ref name=Liakos2017>{{citation |postscript=.
 | title=Catalogue and properties of δ Scuti stars in binaries
 | last1=Liakos | first1=Alexios | last2=Niarchos | first2=Panagiotis
 | journal=Monthly Notices of the Royal Astronomical Society
 | volume=465 | issue=1 | pages=1181–1200 | date=February 2017
 | doi=10.1093/mnras/stw2756 | doi-access=free
 | bibcode=2017MNRAS.465.1181L |arxiv = 1611.00200 }}</ref>

[[Epsilon Delphini]], Deneb Dulfim ([[Arab astrology|lit.]] "tail [of the] Dolphin"), or Aldulfin, is a star of [[stellar classification|stellar class]] B6&nbsp;III.<ref name=Lesh1968>{{citation
 | last=Lesh | first=Janet Rountree | postscript=.
 | title=The Kinematics of the Gould Belt: an Expanding Group?
 | journal=Astrophysical Journal Supplement
 | volume=17 | page=371 | date=December 1968
 | doi=10.1086/190179 | bibcode=1968ApJS...17..371L | doi-access=free }}</ref> Its magnitude is variable at around 4.03.<ref>{{citation
 | display-authors=1 | last1=Samus | first1=N. N.
 | last2=Kazarovets | first2=E.V. | last3=Durlevich | first3=O.V.
 | last4=Kireeva | first4=N.N. | last5=Pastukhova | first5=E.N.
 | title=General Catalogue of Variable Stars | postscript=.
 | version=GCVS 5.1 | journal=Astronomy Reports | date=January 2017
  | volume=61 | issue=1 | pages=80–88
 | bibcode=2017ARep...61...80S | doi=10.1134/S1063772917010085 | s2cid=125853869 }}</ref><ref name=Crawford1971>{{citation
 | display-authors=1 | last1=Crawford | first1=D. L.
 | last2=Barnes | first2=J. V. | last3=Golson | first3=J. C.
 | title=Four-color, H-beta, and UBV photometry for bright B-type stars in the northern hemisphere
 | journal=The Astronomical Journal
 | year=1971 | pages=1058 | volume=76 | postscript=.
 | bibcode=1971AJ.....76.1058C | doi=10.1086/111220 }}</ref>

[[Zeta Delphini]], an A3Va<ref name=Zeta /> main-sequence star of magnitude 4.6, was in 2014 discovered to have a [[brown dwarf]] orbiting around it. Zeta Delphini B has a mass of 50±15 {{jupiter mass}}.<ref name=Zeta>{{cite journal |last1=De Rosa |first1=R. J. |last2=Patience |first2=J. |last3=Ward-Duong |first3=K. |last4=Vigan |first4=A. |last5=Marois |first5=C. |last6=Song |first6=I. |last7=Macintosh |first7=B. |last8=Graham |first8=J. R. |last9=Doyon |first9=R. |last10=Bessell |first10=M. S. |last11=Lai |first11=O. |last12=McCarthy |first12=D. W. |last13=Kulesa |first13=C. |title=The VAST Survey - IV. A wide brown dwarf companion to the A3V star ζ Delphini |journal=Monthly Notices of the Royal Astronomical Society |date=December 2014 |volume=445 |issue=4 |page=3694 |doi=10.1093/mnras/stu2018 |arxiv=1410.0005 |bibcode=2014MNRAS.445.3694D |language=en |issn=0035-8711|doi-access=free }}</ref>

[[Image:Aquila.fade-in.animation.webm|thumb|upright=1.2|right|Animation fading-in of [[Aquila (constellation)|Aquila]], Delphinus, [[Sagitta]], and the summer [[Milky Way]] as seen in [[Westhavelland Nature Park|Dark-sky preserve Westhavelland]]]]
[[Rho Aquilae]] at magnitude 4.94<ref name=scfs /> is at about 150 light-years away.<ref name=scfs>{{citation | display-authors=1 | title=Sixth Catalogue of Fundamental Stars (FK6). Part I. Basic fundamental stars with direct solutions | last1=Wielen | first1=R. | last2=Schwan | first2=H. | last3=Dettbarn | first3=C. | last4=Lenhardt | first4=H. | last5=Jahreiß | first5=H. | last6=Jährling | first6=R. | journal=Veroeffentlichungen des Astronomischen Rechen-Instituts Heidelberg | publisher=Astronomisches Rechen-Institut Heidelberg | issue=35 | year=1999 | volume=35 | page=1 | bibcode=1999VeARI..35....1W | postscript=. }}</ref> Due to its [[proper motion]], it has been in the (round-figure parameter) bounds of the constellation since 1992.<ref>{{cite book|author=Patrick Moore|title=The Observer's Year: 366 Nights of the Universe|url=https://books.google.com/books?id=p87TBwAAQBAJ&pg=PA132|date=29 June 2013|publisher=Springer Science & Business Media|isbn=978-1-4471-3613-2|pages=132–}}</ref> It is an [[A-type main sequence star]] with a lower metallicity than the Sun.<ref name=starhorse>{{citation |postscript=. |last1=Anders |first1=F. |last2=Khalatyan |first2=A. |last3=Chiappini |first3=C. |last4=Queiroz |first4=A. B. |last5=Santiago |first5=B. X. |last6=Jordi |first6=C. |last7=Girardi |first7=L. |last8=Brown |first8=A. G. A. |last9=Matijevic |first9=G. |last10=Monari |first10=G. |last11=Cantat-Gaudin |first11=T. |last12=Weiler |first12=M. |last13=Khan |first13=S. |last14=Miglio |first14=A. |last15=Carrillo |first15=I. |last16=Romero-Gómez |first16=M. |last17=Minchev |first17=I. |last18=de Jong |first18=R. S. |last19=Antoja |first19=T. |last20=Ramos |first20=P. |last21=Steinmetz |first21=M. |last22=Enke |first22=H. |title=Photo-astrometric distances, extinctions, and astrophysical parameters for Gaia DR2 stars brighter than G = 18 |journal=Astronomy and Astrophysics |date=1 August 2019 |volume=628 |pages=A94 |doi=10.1051/0004-6361/201935765 |arxiv=1904.11302 |bibcode=2019A&A...628A..94A |s2cid=131780028 |issn=0004-6361}}</ref>

[[HR Delphini]] was a [[nova]] that brightened to magnitude 3.5 in December 1967.<ref name=isles67>{{cite journal | title = HR Delphini (Nova 1967) in 1967 - 71 | author =Isles, J. E.|journal =Journal of the British Astronomical Association | volume= 85|pages= 54–58| year=1974|bibcode =1974JBAA...85...54I}}</ref> It took an unusually long time for the nova to reach peak brightness which indicate that it barely satisfied the conditions for a thermonuclear runaway.<ref>{{cite journal |last1=Friedjung |first1=M |title=The unusual nature of nova HR Delphini 1967 |journal=Astronomy & Astrophysics |date=17 March 1992 |volume=262 |issue=262 |page=487 |bibcode=1992A&A...262..487F |url=https://ui.adsabs.harvard.edu/abs/1992A%26A...262..487F/abstract |access-date=19 July 2020}}</ref> Another nova by the name [[V339 Delphini]] was detected in 2013; it peaked at magnitude 4.3 and was the first nova observed to produce lithium.<ref>{{cite journal |last1=Tajitsu |first1=Akito |last2=Sadakane |first2=Kozo |last3=Naito |first3=Hiroyuki |last4=Arai |first4=Akira |last5=Aoki |first5=Wako |title=Explosive lithium production in the classical nova V339 Del (Nova Delphini 2013) |journal=Nature |date=18 February 2015 |volume=518 |issue=7539 |pages=381–384 |doi=10.1038/nature14161|pmid=25693569 |arxiv=1502.05598 |bibcode=2015Natur.518..381T |s2cid=205242345 }}</ref><ref>{{cite web
|url=http://www.universetoday.com/104103/bright-new-nova-in-delphinus-you-can-see-it-tonight-with-binoculars
|author=King, Bob
|title=Bright New Nova In Delphinus — You can See it Tonight With Binoculars
|work=Universe Today (initial designation PNV J20233073+2046041)
|date=August 14, 2013
|access-date=August 15, 2013}}</ref><ref>{{cite web
|url=http://remanzacco.blogspot.it/2013/08/possible-bright-nova-in-delphinus.html
|title=Possible Bright Nova in Delphinus
|publisher=Associazione Friulana di Astronomia e Meteorologia
|last1=Guido |first1=Ernesto| first2=Nello |last2=Ruocco |first3=Nick |last3=Howes
|date=August 15, 2013
|access-date=August 15, 2013}}</ref><ref>{{cite web
|url=http://www.virtualtelescope.eu/2013/08/15/possible-nova-pnv-j202330732046041-in-delphinus/
|title=Nova Delphini 2013 (formerly PNV J20233073+2046041): images, spectra and maps
|publisher=[[Gianluca Masi]] - [[Virtual Telescope Project]] |last1=Masi|first1=Gianluca|date=August 15, 2013
|access-date=August 15, 2013}}</ref>

[[Musica (star)|Musica]], also known by its Flamsteed designation 18 Delphini, is one of the five stars with known planets located in Delphinus. It has a spectral type of G6 III.<ref>{{cite journal
 | title=The spectrophotometric parallaxes of 42 visual binaries
 | last=Opolski | first=A.
 | journal=Arkiv för Astronomi
 | volume=2 | pages=55 | year= 1957
 | bibcode=1957ArA.....2...55O }}</ref> [[Arion (planet)|Arion]], the planet, is a very dense and massive planet with a mass at least 10.3 times greater than Jupiter.<ref>{{cite journal |last1=Sato |first1=Bun’ei |last2=Izumiura |first2=Hideyuki |last3=Toyota |first3=Eri |last4=Kambe |first4=Eiji |last5=Ikoma |first5=Masahiro |last6=Omiya |first6=Masashi |last7=Masuda |first7=Seiji |last8=Takeda |first8=Yoichi |last9=Murata |first9=Daisuke |last10=Itoh |first10=Yoichi |last11=Ando |first11=Hiroyasu |last12=Yoshida |first12=Michitoshi |last13=Kokubo |first13=Eiichiro |last14=Ida |first14=Shigeru |title=Planetary Companions around Three Intermediate-Mass G and K Giants: 18 Delphini, ξ Aquilae, and HD 81688 |journal=Publications of the Astronomical Society of Japan |date=25 June 2008 |volume=60 |issue=3 |pages=539–550 |doi=10.1093/pasj/60.3.539 |arxiv=0802.2590 |bibcode=2008PASJ...60..539S |url=https://academic.oup.com/pasj/article/60/3/539/1508408 |language=en |issn=0004-6264|doi-access=free }}</ref> Arion was part of the first [[NameExoWorlds]] contest where the public got the opportunity to suggest names for exoplanets and their host stars.<ref>{{cite web |title=International Astronomical Union {{!}} IAU |url=https://www.iau.org/news/pressreleases/detail/iau1514/ |website=www.iau.org |access-date=19 July 2020}}</ref>

===Exoplanets===

In 2024 the planet [[TOI-6883 b]] was discovered in the constellation Delphinus.<ref>{{Cite web |last=Martin |first=Pierre-Yves |date=2024 |title=Planet TOI-6883 b |url=https://exoplanet.eu/catalog/toi_6883_b--8968/ |access-date=2024-05-30 |website=exoplanet.eu |language=en}}</ref> It has a 16.249 day orbital period around its host star,<ref name=":0">{{Cite journal |last1=Sgro |first1=Lauren A. |title=Confirmation and Characterization of the Eccentric, Warm Jupiter TIC 393818343 b with a Network of Citizen Scientists |date=2024-05-23 |arxiv=2405.15021 |last2=Dalba |first2=Paul A. |last3=Esposito |first3=Thomas M. |last4=Marchis |first4=Franck |last5=Dragomir |first5=Diana |last6=Villanueva Jr. |first6=Steven |last7=Fulton |first7=Benjamin |last8=Billiani |first8=Mario |last9=Loose |first9=Margaret|journal=The Astronomical Journal |volume=168 |issue=1 |page=26 |doi=10.3847/1538-3881/ad5096 |doi-access=free |bibcode=2024AJ....168...26S }}</ref> a radius 1.08 times Jupiter's,<ref name=":1">{{Cite journal |last1=Conzo |first1=G. |last2=Moriconi |first2=M. |date=2024-02-26 |title=TOI-6883.01: A Single-transit Planet Candidate Detected from TESS |journal=Research Notes of the AAS |volume=8 |issue=2 |pages=53 |doi=10.3847/2515-5172/ad2c85 |doi-access=free |bibcode=2024RNAAS...8...53C |issn=2515-5172}}</ref> and a mass 4.34 times Jupiter's.<ref name=":0" /> It was discovered from a single transit<ref name=":1" /> in TESS data and it was confirmed by a network of citizen scientists.<ref name=":0" /> 

In 2024, the planet TOI-6883 c was discovered in the constellation Delphinus.<ref>{{Cite web |last=Martin |first=Pierre-Yves |date=2024 |title=Planet TOI-6883 c |url=https://exoplanet.eu/catalog/toi_6883_c--10778/ |access-date=2024-10-20 |website=exoplanet.eu |language=en}}</ref> It has an orbital period of 7.8458 days, a radius of 0.7 times Jupiter's, and a third of Jupiter's mass. The Neptunian-size planet was discovered from an abnormality in data retrieved from TOI-6883 c.<ref>{{cite arXiv |last1=Conzo |first1=G. |title=TIC 393818343 c: Discovery and characterization of a Neptune-like planet in the Delphinus constellation |date=2024-10-09 |eprint=2410.07425 |last2=Leiner |first2=N. |last3=Lynch |first3=K. |last4=Moriconi |first4=M. |last5=Ruocco |first5=N. |last6=Scarmato |first6=T.|class=astro-ph.EP }}</ref>

===Deep-sky objects===
Its rich [[Milky Way]] star field means many modestly deep-sky objects. [[NGC 6891]] is a [[planetary nebula]] of magnitude 10.5; another is [[NGC 6905]] or the Blue Flash Nebula. The Blue Flash Nebula shows broad emission lines. The central star in NGC 6905 has a spectral type of WO2, meaning it is rich in oxygen.<ref name=GomezGonzalez>{{cite journal|doi=10.1093/mnras/stab3042|arxiv=2110.09551 |title=Planetary nebulae with Wolf–Rayet-type central stars – III. A detailed view of NGC 6905 and its central star|year=2022|last1=Gómez-González|first1=V M A.|last2=Rubio|first2=G.|last3=Toalá|first3=J. A.|last4=Guerrero|first4=M. A.|last5=Sabin|first5=L.|last6=Todt|first6=H.|last7=Gómez-Llanos|first7=V.|last8=Ramos-Larios|first8=G.|last9=Mayya|first9=Y. D.|journal=Monthly Notices of the Royal Astronomical Society|volume=509|pages=974–989|doi-access=free }}</ref> 

[[NGC 6934]] is a [[globular cluster]] of magnitude 9.75.  It is about 52,000 light-years away from the Solar System.<ref>{{cite journal
 | title=Orbits of Globular Clusters in the Outer Galaxy: NGC 7006
 | last1=Dinescu | first1=Dana I. | last2=Majewski | first2=Steven R.
 | last3=Girard | first3=Terrence M. | last4=Cudworth | first4=Kyle M.
 | display-authors=1 | journal=The Astronomical Journal
 | volume=122 | issue=4 | pages=1916–1927 | date=October 2001
 | arxiv=astro-ph/0106259 | bibcode=2001AJ....122.1916D 
 | doi=10.1086/323094 | s2cid=1232455 }}</ref> It is in the [[Shapley-Sawyer Concentration Class]] VIII<ref name=ShapleySawyer>{{citation
 | title=A Classification of Globular Clusters
 | last1=Shapley | first1=Harlow | last2=Sawyer | first2=Helen B.
 | journal=Harvard College Observatory Bulletin
 | volume=849 | issue=849 | pages=11–14 | date=August 1927
 | bibcode=1927BHarO.849...11S | postscript=. }}</ref> and is thought to share a common origin with another globular cluster in [[Boötes]].<ref name=apj670_1_363>{{citation
 | title=A 1.4 GHz Arecibo Survey for Pulsars in Globular Clusters
 | display-authors=1 | last1=Hessels | first1=J. W. T.
 | last2=Ransom | first2=S. M. | last3=Stairs | first3=I. H.
 | last4=Kaspi | first4=V. M. | last5=Freire | first5=P. C. C.
 | journal=The Astrophysical Journal
 | volume=670 | issue=1 | pages=363–378 | date=November 2007
 | bibcode=2007ApJ...670..363H  | arxiv=0707.1602
 | doi=10.1086/521780 | s2cid=16914232 | postscript=. }}</ref> It has an intermediate metallicity for a globular cluster,<ref name=Kaluzny2001>{{cite journal
 | title=Image-Subtraction Photometry of Variable Stars in the Field of the Globular Cluster NGC 6934
 | display-authors=1 | last1=Kaluzny | first1=J.
 | last2=Olech | first2=A. | last3=Stanek | first3=K. Z.
 | journal=The Astronomical Journal
 | volume=121 | issue=3 | pages=1533–1550 | date=March 2001
 | arxiv=astro-ph/0010303 | bibcode=2001AJ....121.1533K 
 | doi=10.1086/319411 | s2cid=14431121 }}</ref> but as of 2018 it has been poorly studied.<ref>{{cite journal
 | title=Metallicity Variations in the Type II Globular Cluster NGC 6934
 | last1=Marino | first1=A. F. | last2=Yong | first2=D.
 | last3=Milone | first3=A. P. | last4=Piotto | first4=G.
 | last5=Lundquist | first5=M. | last6=Bedin | first6=L. R.
 | last7=Chené | first7=A. -N. | last8=Da Costa | first8=G.
 | last9=Asplund | first9=M. | last10=Jerjen | first10=H.
 | display-authors=1 | journal=The Astrophysical Journal
 | volume=859 | issue=2 | id=81 | pages=20 | date=June 2018
 | arxiv=1804.04158 | bibcode=2018ApJ...859...81M 
 | doi=10.3847/1538-4357/aabdea | s2cid=119461759 | doi-access=free }}</ref> At a distance of about 137,000 light-years,<ref name=apj670_1_363 /> the globular cluster [[NGC 7006]] is at the outer reaches of the galaxy. It is also fairly dim at magnitude 11.5 and is in Class I.<ref name=ShapleySawyer />

==See also==
* [[Delphinus (Chinese astronomy)]]

==Notes==
{{Notelist}}

==Citations==
{{Reflist}}

==References==
* {{cite book
  | last = Makemson
  | first = Maud Worcester
  | year = 1941
  | publisher = [[Yale University Press]]
  | title = The Morning Star Rises: An Account of Polynesian Astronomy	
  | bibcode = 1941msra.book.....M
 }}
* {{cite book |last1=Ridpath |first1=Ian |last2=Tirion |first2=Wil |title=Stars and planets guide |date=2017 |publisher=Collins |location=London |isbn=978-0-00-823927-5}} Princeton University Press, Princeton. {{ISBN|978-0-691-17788-5}}.
<!-- Source of values for stars: www.alcyone.de; mainly from catalogues BSC/HR -->
<!-- Source of values for "nebulae": mainly RNGC -->
*[[University of Wisconsin]], [http://www.astro.wisc.edu/~dolan/constellations/constellations/Delphinus.html "Delphinus"] {{Webarchive|url=https://web.archive.org/web/20160307160324/http://www.astro.wisc.edu/~dolan/constellations/constellations/Delphinus.html |date=2016-03-07 }}

== External links ==
{{Commons}}
* [http://www.allthesky.com/constellations/delphinus/ The Deep Photographic Guide to the Constellations: Delphinus]
* [http://astrojan.nhely.hu/delphin.htm The clickable Delphinus]
* [http://www.ianridpath.com/startales/delphinus.html Star Tales – Delphinus]
* [https://iconographic.warburg.sas.ac.uk/category/vpc-taxonomy-017054 Warburg Institute Iconographic Database (medieval and early modern images of Delphinus)]

{{Stars of Delphinus}}
{{Constellations}}
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