Delphinus (Pronounced or ) is a small
constellation in the
Northern Celestial Hemisphere, 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. This plane of reference bases the equatorial coordinate system. In other words, the celestial equator is an abstract proj ...
. Its name is the
Latin
Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
version for the
Greek
Greek may refer to:
Greece
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 ...
word for
dolphin
A dolphin is an aquatic mammal within the infraorder Cetacea. Dolphin species belong to the families Delphinidae (the oceanic dolphins), Platanistidae (the Indian river dolphins), Iniidae (the New World river dolphins), Pontoporiidae (the ...
(). It is one of the 48 constellations listed by the 2nd century astronomer
Ptolemy
Claudius Ptolemy (; grc-gre, Πτολεμαῖος, ; la, Claudius Ptolemaeus; AD) was a mathematician, astronomer, astrologer, geographer, and music theorist, who wrote about a dozen scientific treatises, three of which were of importance ...
, and remains one of the 88 modern constellations recognized by the
International Astronomical Union
The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...
. 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,
Aquarius
Aquarius may refer to:
Astrology
* Aquarius (astrology), an astrological sign
* Age of Aquarius, a time period in the cycle of astrological ages
Astronomy
* Aquarius (constellation)
* Aquarius in Chinese astronomy
Arts and entertainme ...
,
Equuleus
Equuleus ( ) is a constellation of stars that are visible in the night sky. Its name is Latin for "little horse", a foal. Located just north of the celestial equator, it was one of the 48 constellations listed by the 2nd century astronomer Ptolem ...
and
Pegasus.
Delphinus is a faint constellation with only two stars brighter than an
apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or other astronomical object observed from Earth. An object's apparent magnitude depends on its intrinsic luminosity, its distance from Earth, and any extinction of the object's ...
of 4,
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 companions ...
(Sualocin) at magnitude 3.8.
Mythology
Delphinus is associated with two stories from
Greek mythology
A major branch of classical mythology, Greek mythology is the body of myths originally told by the ancient Greeks, and a genre of Ancient Greek folklore. These stories concern the origin and nature of the world, the lives and activities ...
.
According to myth, the first Greek god
Poseidon
Poseidon (; grc-gre, Ποσειδῶν) was one of the Twelve Olympians in ancient Greek religion and myth, god of the sea, storms, earthquakes and horses.Burkert 1985pp. 136–139 In pre-Olympian Bronze Age Greece, he was venerated as a ...
wanted to marry
Amphitrite
In ancient Greek mythology, Amphitrite (; grc-gre, Ἀμφιτρίτη, Amphitrítē) was the goddess of the sea, the queen of the sea, and the wife of Poseidon. She was a daughter of Nereus and Doris (or Oceanus and Tethys).Roman, L., & Ro ...
, a beautiful
nereid
In Greek mythology, the Nereids or Nereides ( ; grc, Νηρηΐδες, Nērēḯdes; , 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 ...
. 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 was able to persuade 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 of
Lesbos
Lesbos or Lesvos ( el, Λέσβος, Lésvos ) 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. It is separated from Asia Minor by the nar ...
(7th century BC), who was saved by a dolphin. 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
In
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 Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twe ...
, the stars of Delphinus are located within ''
the Black Tortoise of the North'' (北方玄武, ''Běi Fāng Xuán Wǔ'').
In
Polynesia
Polynesia () "many" and νῆσος () "island"), to, Polinisia; mi, Porinihia; haw, Polenekia; fj, Polinisia; sm, Polenisia; rar, Porinetia; ty, Pōrīnetia; tvl, Polenisia; tkl, Polenihia (, ) is a subregion of Oceania, made up of ...
, two cultures recognized Delphinus as a constellation. In
Pukapuka
Pukapuka, formerly Danger Island, is a coral atoll in the northern group of the Cook Islands in the Pacific Ocean. It is one of most remote islands of the Cook Islands, situated about northwest of Rarotonga. On this small island, an ancient ...
, it was called ''Te Toloa'' and in the
Tuamotus
The Tuamotu Archipelago or the Tuamotu Islands (french: Îles Tuamotu, 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, extendin ...
, it was called ''Te Uru-o-tiki''.
In
Hindu astrology
Jyotisha or Jyotishya (from Sanskrit ', from ' “light, heavenly body" and ''ish'' - from Isvara or God) is the traditional Hindu system of astrology, also known as Hindu astrology, Indian astrology and more recently Vedic astrology. It is one ...
, the Delphinus corresponds to the
Nakshatra, or lunar mansion, of
Dhanishta.
Characteristics
Delphinus is bordered 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 ...
to the north,
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 ...
to the northwest,
Aquila to the west and southwest,
Aquarius
Aquarius may refer to:
Astrology
* Aquarius (astrology), an astrological sign
* Age of Aquarius, a time period in the cycle of astrological ages
Astronomy
* Aquarius (constellation)
* Aquarius in Chinese astronomy
Arts and entertainme ...
to the southeast,
Equuleus
Equuleus ( ) is a constellation of stars that are visible in the night sky. Its name is Latin for "little horse", a foal. Located just north of the celestial equator, it was one of the 48 constellations listed by the 2nd century astronomer Ptolem ...
to the east and
Pegasus 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".equatorial coordinate system
The equatorial coordinate system is a celestial coordinate system widely used to specify the positions of celestial objects. It may be implemented in spherical or rectangular coordinates, both defined by an origin at the centre of Earth, a fu ...
, the
right ascension coordinates of these borders lie between and , while the
declination coordinates are between and .
The whole constellation is visible to observers north of latitude
69°S.
[
]
Features
Stars
Delphinus has two stars above fourth (apparent) magnitude; its brightest star is of magnitude 3.6. The main asterism in Delphinus is Job's Coffin, nearly a 45°-apex lozenge
Lozenge or losange may refer to:
* Lozenge (shape), a type of rhombus
*Throat lozenge, a tablet intended to be dissolved slowly in the mouth to suppress throat ailments
*Lozenge (heraldry), a diamond-shaped object that can be placed on the field of ...
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 Observatory director, Niccolò Cacciatore
Niccolò Cacciatore (; 26 January 1770 – 28 January 1841) was an Italian astronomer.
Cacciatore was born at Casteltermini, in Sicily. While studying mathematics and physics in Palermo, he became acquainted with Giuseppe Piazzi, head of the Pa ...
(d. 1841).
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 companions ...
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.
Beta Delphini is officially called Rotanev.[ It was found to be a binary star in 1873.] The gap between its close binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
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 form 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 star
An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...
of magnitude 4.43. It is a spectroscopic binary, and both stars are Delta Scuti variable
A Delta Scuti variable (sometimes termed dwarf cepheid when the V-band amplitude is larger than 0.3 mag.) is a subclass of young pulsating star.
These variables as well as classical cepheids are important standard candles and have been used to es ...
s.
Epsilon Delphini, Deneb Dulfim ( lit. "tail f theDolphin"), or Aldulfin, is a star of stellar class B6 III. Its magnitude is variable at around 4.03, at 330 ly.
Zeta Delphini, an A3Va main-sequence star of magnitude 4.6, was in 2014 discovered to have a brown dwarf
Brown dwarfs (also called failed stars) are substellar objects that are not massive enough to sustain nuclear fusion of ordinary hydrogen ( 1H) into helium in their cores, unlike a main-sequence star. Instead, they have a mass between the most ...
orbiting around it. Zeta Delphini B has a mass of 50±15 .
In Delphinus, in extremes of distance, Gliese 795 is the closest known star at 54.95 ly and rapidly moves east over a period of centuries (863±3 arcseconds per year); whereas the giant of blue colour, W Delphini is at 2203.81 ly at 9.76 magnitude.[ Its brightness ranges from a magnitude of 12.3 to a magnitude of 9.7 over its variable period as it is a Beta Persei star-type semi-detached system. Other variable stars of large amateur telescopic visibility include R Delphini, a Mira-type variable star with a period of 285.5 days. Its magnitude ranges between a maximum 7.6 and a minimum 13.8.
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
An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...
with a lower metallicity than the Sun.
HR Delphini
HR Delphini, also known as Nova Delphini 1967, was a nova which appeared in the constellation Delphinus in 1967. It was discovered by George Alcock at 22:35 UT on 8 July 1967, after searching the sky for over 800 hours with binocular ...
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, 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, 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
NameExoWorlds (also known as IAU NameExoWorlds) is the name of various projects managed by the International Astronomical Union (I.A.U.) to encourage names to be submitted for astronomical objects, which would later be considered for official ad ...
contest where the public got the opportunity to suggest names for exoplanets and their host stars.
Deep-sky objects
Its rich Milky Way
The Milky Way is the galaxy that includes our Solar System, with the name describing the galaxy's appearance from Earth: a hazy band of light seen in the night sky formed from stars that cannot be individually distinguished by the naked eye. ...
star field means many modestly deep-sky objects. NGC 6891 is a planetary nebula
A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
The term "planetary nebula" is a misnomer because they are unrelate ...
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 of WO2, meaning it is rich in oxygen.
NGC 6934 is a globular cluster
A globular cluster is a spheroidal conglomeration of stars. Globular clusters are bound together by gravity, with a higher concentration of stars towards their centers. They can contain anywhere from tens of thousands to many millions of membe ...
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.
See also
* Delphinus (Chinese astronomy)
Notes
Citations
References
*
* Ian Ridpath and Wil Tirion (2017). ''Stars and Planets Guide'', Collins, London. . Princeton University Press, Princeton. .
*University of Wisconsin
A university () is an institution of higher (or tertiary) education and research which awards academic degrees in several academic disciplines. Universities typically offer both undergraduate and postgraduate programs. In the United States, ...
"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
Constellations
Northern constellations
Constellations listed by Ptolemy
Legendary mammals
Constellation
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