Delphinus is a small

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The first constellati ...

in the

Northern Celestial Hemisphere The northern celestial hemisphere, also called the Northern Sky, is the Northern Hemisphere, northern half of the celestial sphere; that is, it lies north of the celestial equator. This arbitrary sphere diurnal motion, appears to rotate westward ...

, close to the

celestial equator The celestial equator is the great circle of the imaginary celestial sphere on the same plane as the equator of Earth. By extension, it is also a plane of reference in the equatorial coordinate system. Due to Earth's axial tilt, the celestial ...

. Its name is the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

version for the

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

word for

dolphin A dolphin is an aquatic mammal in the cetacean clade Odontoceti (toothed whale). Dolphins belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontopori ...

(). It is one of the 48 constellations listed by the 2nd-century astronomer

Ptolemy Claudius Ptolemy (; , ; ; – 160s/170s AD) was a Greco-Roman mathematician, astronomer, astrologer, geographer, and music theorist who wrote about a dozen scientific treatises, three of which were important to later Byzantine science, Byzant ...

, and remains one of the 88 modern constellations recognized by the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

. It is one of the smaller constellations, ranked 69th in size. Delphinus' five brightest stars form a distinctive asterism symbolizing a dolphin with four stars representing the body and one the tail. It is bordered (clockwise from north) by

Vulpecula Vulpecula is a faint constellation in the northern sky. Its name is Latin for "little fox", although it is commonly known simply as the fox. It was identified in the seventeenth century, and is located in the middle of the Summer Triangle (an ...

Sagitta Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by t ...

Aquila Aquila may refer to: Arts, entertainment, and media * ''Aquila'', a series of books by S.P. Somtow * ''Aquila'', a 1997 book by Andrew Norriss * ''Aquila'' (children's magazine), a UK-based children's magazine * ''Aquila'' (journal), an orni ...

, Aquarius,

Equuleus Equuleus is a faint constellation located just north of the celestial equator. Its name is Latin for "little horse", a foal. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains one of the 88 modern const ...

and

Pegasus Pegasus (; ) is a winged horse in Greek mythology, usually depicted as a white stallion. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. Pegasus was the brother of Chrysaor, both born from Medusa's blood w ...

. Delphinus is a faint constellation with only two stars brighter than an

apparent magnitude Apparent magnitude () is a measure of the Irradiance, brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction (astronomy), ...

of 4,

Beta Delphini Beta Delphini (β Delphini, abbreviated Beta Del, β Del) is a binary star in the constellation of Delphinus. It is the brightest star in Delphinus. The two components of the system are designated Beta Delphini ...

(Rotanev) at magnitude 3.6 and

Alpha Delphini Alpha Delphini (α Delphini, abbreviated Alpha Del, α Del) is a multiple star system in the constellation of Delphinus. It consists of a triple star, designated Alpha Delphini A, together with five faint, probably optical compani ...

(Sualocin) at magnitude 3.8.

Mythology

Delphinus is associated with two stories from

Greek mythology Greek mythology is the body of myths originally told by the Ancient Greece, ancient Greeks, and a genre of ancient Greek folklore, today absorbed alongside Roman mythology into the broader designation of classical mythology. These stories conc ...

. According to myth, the first Greek god

Poseidon Poseidon (; ) is one of the twelve Olympians in ancient Greek religion and mythology, presiding over the sea, storms, earthquakes and horses.Burkert 1985pp. 136–139 He was the protector of seafarers and the guardian of many Hellenic cit ...

wanted to marry

Amphitrite In ancient Greek mythology, Amphitrite (; ) was the goddess of the sea, the queen of the sea, and her consort is Poseidon. She was a daughter of Nereus and Doris (or Oceanus and Tethys).Roman, L., & Roman, M. (2010). Under the influence ...

, a beautiful

nereid In Greek mythology, the Nereids or Nereides ( ; ; , also Νημερτές) are sea nymphs (female spirits of sea waters), the 50 daughters of the ' Old Man of the Sea' Nereus and the Oceanid Doris, sisters to their brother Nerites. They ofte ...

. 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. The second story tells of the Greek poet

Arion Arion (; ) was a kitharode in ancient Greece, a Dionysiac poet credited with inventing the dithyramb. The islanders of Lesbos claimed him as their native son, but Arion found a patron in Periander, tyrant of Corinth. Although notable for his mu ...

Lesbos Lesbos or Lesvos ( ) is a Greek island located in the northeastern Aegean Sea. It has an area of , with approximately of coastline, making it the third largest island in Greece and the List of islands in the Mediterranean#By area, eighth largest ...

(7th century BC), who a dolphin saved. 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 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. 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.

In non-Western astronomy

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The Ancient China, ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categori ...

, the stars of Delphinus are located within '' the Black Tortoise of the North'' (北方玄武, ''Běi Fāng Xuán Wǔ''). In

Polynesia Polynesia ( , ) is a subregion of Oceania, made up of more than 1,000 islands scattered over the central and southern Pacific Ocean. The indigenous people who inhabit the islands of Polynesia are called Polynesians. They have many things in ...

, two cultures recognized Delphinus as a constellation. In

Pukapuka Pukapuka, formerly Danger Island, is a coral atoll in the Northern Cook Islands, northern group of the Cook Islands in the Pacific Ocean. It is one of the most remote islands of the Cook Islands, situated about northwest of Rarotonga. On th ...

, it was called ''Te Toloa'' and in the

Tuamotus The Tuamotu Archipelago or the Tuamotu Islands (, officially ) are a French Polynesian chain of just under 80 islands and atolls in the southern Pacific Ocean. They constitute the largest chain of atolls in the world, extending (from northwest to ...

, it was called ''Te Uru-o-tiki''. In Hindu astrology, the Delphinus corresponds to the

Nakshatra Nakshatra () is the term for Lunar mansion in Hindu astrology and Buddhist astrology. A nakshatra is one of 27 (sometimes also 28) sectors along the ecliptic. Their names are related to a prominent star or asterisms in or near the respective s ...

, or lunar mansion, of Dhanishta.

Characteristics

Delphinus is bordered by

to the north,

to the northwest,

to the west and southwest, Aquarius to the southeast,

to the east and

to the east. Covering 188.5 square degrees, corresponding to 0.457% of the sky, it ranks 69th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the IAU in 1922, is "Del". The official constellation boundaries, as set by

Eugène Delporte Eugene is a common male given name that comes from the Greek εὐγενής (''eugenēs''), "noble", literally "well-born", from εὖ (''eu''), "well" and γένος (''genos''), "race, stock, kin". The whole constellation is visible to observers north of latitude 69th parallel south, 69°S.

Features

Stars

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).

is a blue-white hued main sequence star of magnitude 3.8, 241 light-years from Earth. It is a spectroscopic binary. It is officially named Sualocin. The star has an absolute magnitude of -0.4.

is officially called Rotanev. It was found to be a binary star in 1873. 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. 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. 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. An unconfirmed exoplanet with a minimum mass of 0.7 Jupiter masses may orbit one of the stars. Delta Delphini is a type A-type main sequence star, A-type star of magnitude 4.43. It is a spectroscopic binary, and both stars are Delta Scuti variables. Epsilon Delphini, Deneb Dulfim (Arab astrology, lit. "tail [of the] Dolphin"), or Aldulfin, is a star of stellar classification, stellar class B6 III. Its magnitude is variable at around 4.03. Zeta Delphini, an A3Va 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 . Rho Aquilae at magnitude 4.94 is at about 150 light-years away. Due to its proper motion, it has been in the (round-figure parameter) bounds of the constellation since 1992. It is an A-type main sequence star with a lower metallicity than the Sun. HR Delphini was a nova that brightened to magnitude 3.5 in December 1967. 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. 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. 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. Arion (planet), Arion, the planet, is a very dense and massive planet with a mass at least 10.3 times greater than Jupiter. Arion was part of the first NameExoWorlds contest where the public got the opportunity to suggest names for exoplanets and their host stars.

Exoplanets

In 2024 the planet TOI-6883 b was discovered in the constellation Delphinus. It has a 16.249 day orbital period around its host star, a radius 1.08 times Jupiter's, and a mass 4.34 times Jupiter's. It was discovered from a single transit in TESS data and it was confirmed by a network of citizen scientists. In 2024, the planet TOI-6883 c was discovered in the constellation Delphinus. 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.

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. NGC 6934 is a globular cluster of magnitude 9.75. It is about 52,000 light-years away from the Solar System. It is in the Shapley-Sawyer Concentration Class VIII and is thought to share a common origin with another globular cluster in Boötes. It has an intermediate metallicity for a globular cluster, but as of 2018 it has been poorly studied. At a distance of about 137,000 light-years, 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.

Notes

Citations

References

* * Princeton University Press, Princeton. . *University of Wisconsin
"Delphinus"

External links

The Deep Photographic Guide to the Constellations: Delphinus

Warburg Institute Iconographic Database (medieval and early modern images of Delphinus)
{{DEFAULTSORT:Delphinus Constellation Delphinus, Constellations Northern constellations Constellations listed by Ptolemy Legendary mammals Articles containing video clips