Equuleus
Encyclopedia
Equuleus is a constellation
. 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 constellations. It is the second smallest of the modern constellations (after Crux
), spanning only 72 square degrees. It is also very faint, having no stars brighter than the fourth magnitude
.
(Kitalpha), at magnitude 3.92. There are few variable star
s in Equuleus. Only around 25 are known, most of which are faint. γ Equ is an alpha CVn star, ranging between magnitudes 4.58 and 4.77 over a period of around 12½ minutes. R Equ is a Mira variable
that ranges between magnitudes 8.0 and 15.7 over nearly 261 days.
Equuleus contains some double star
s of interest. γ Equ consists of a primary star with a magnitude around 4.7 (slightly variable) and a secondary star of magnitude 11.6, separated by 2 arcseconds. ε Equ consists of four components. The brightest three are of magnitudes 6.0, 6.3, and 7.2. δ Equ
is a binary star
with an orbital period of 5.7 years, which at one time was the shortest known orbital period for an optical binary. The two components of the system are never more than 0.35 arcseconds apart.
, Equuleus contains no notable deep sky objects. Some very faint galaxies
between magnitudes 13 and 15 include NGC 7015, NGC 7040, NGC 7045 and NGC 7046.
, one myth associates Equuleus with the foal Celeris (meaning "swiftness" or "speed"), who was the offspring or brother of the winged horse Pegasus
. Celeris was given to Castor
by Mercury
. Other myths say that Equuleus is the horse struck from Neptune
's trident, during the contest between him and Athena
when deciding which would be the superior. Because this section of stars rises before Pegasus
, it is often called Equus Primus, or the First Horse. Equuleus is also linked to the story of Philyra
and Saturn
.
, the stars that correspond to Equuleus are located within the Black Tortoise of the North
(北方玄武, Běi Fāng Xuán Wǔ).
Constellation
In modern astronomy, a constellation is an internationally defined area of the celestial sphere. These areas are grouped around asterisms, patterns formed by prominent stars within apparent proximity to one another on Earth's night sky....
. Its name is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for 'little horse', a foal
Foal
A foal is an equine, particularly a horse, that is one year old or younger. More specific terms are colt for a male foal and filly for a female foal, but these terms are used until the horse is age three or four. When the foal is nursing from its dam , it may also be called a suckling...
. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy
Ptolemy
Claudius Ptolemy , was a Roman citizen of Egypt who wrote in Greek. He was a mathematician, astronomer, geographer, astrologer, and poet of a single epigram in the Greek Anthology. He lived in Egypt under Roman rule, and is believed to have been born in the town of Ptolemais Hermiou in the...
, and remains one of the 88 modern constellations. It is the second smallest of the modern constellations (after Crux
Crux
Crux is the smallest of the 88 modern constellations, but is one of the most distinctive. Its name is Latin for cross, and it is dominated by a cross-shaped asterism that is commonly known as the Southern Cross.-Visibility:...
), spanning only 72 square degrees. It is also very faint, having no stars brighter than the fourth magnitude
Apparent magnitude
The apparent magnitude of a celestial body is a measure of its brightness as seen by an observer on Earth, adjusted to the value it would have in the absence of the atmosphere...
.
Stars
The brightest star in Equuleus is α EquAlpha Equulei
Alpha Equulei is a star in the constellation Equuleus. It has the traditional name Kitalpha , a contraction of the Arabic name قطعة الفرس "a piece of the horse"....
(Kitalpha), at magnitude 3.92. There are few variable star
Variable star
A star is classified as variable if its apparent magnitude as seen from Earth changes over time, whether the changes are due to variations in the star's actual luminosity, or to variations in the amount of the star's light that is blocked from reaching Earth...
s in Equuleus. Only around 25 are known, most of which are faint. γ Equ is an alpha CVn star, ranging between magnitudes 4.58 and 4.77 over a period of around 12½ minutes. R Equ is a Mira variable
Mira variable
Mira variables , named after the star Mira, are a class of pulsating variable stars characterized by very red colors, pulsation periods longer than 100 days, and light amplitudes greater than one magnitude in infrared and 2.5 magnitude in visual...
that ranges between magnitudes 8.0 and 15.7 over nearly 261 days.
Equuleus contains some double star
Double star
In observational astronomy, a double star is a pair of stars that appear close to each other in the sky as seen from Earth when viewed through an optical telescope. This can happen either because the pair forms a binary star, i.e...
s of interest. γ Equ consists of a primary star with a magnitude around 4.7 (slightly variable) and a secondary star of magnitude 11.6, separated by 2 arcseconds. ε Equ consists of four components. The brightest three are of magnitudes 6.0, 6.3, and 7.2. δ Equ
Delta Equulei
Delta Equulei is the second brightest star in the constellation Equuleus. Delta Equulei is a binary star system about 60 light years away, with components of class G0 and F5. Their combined magnitude is 4.47, and their absolute magnitude is 3.142. There is controversy as to the exact masses of the...
is a binary star
Binary star
A binary star is a star system consisting of two stars orbiting around their common center of mass. The brighter star is called the primary and the other is its companion star, comes, or secondary...
with an orbital period of 5.7 years, which at one time was the shortest known orbital period for an optical binary. The two components of the system are never more than 0.35 arcseconds apart.
Deep sky objects
Due to its small size and its distance from the plane of the Milky WayMilky Way
The Milky Way is the galaxy that contains the Solar System. This name derives from its appearance as a dim un-resolved "milky" glowing band arching across the night sky...
, Equuleus contains no notable deep sky objects. Some very faint galaxies
Galaxy
A galaxy is a massive, gravitationally bound system that consists of stars and stellar remnants, an interstellar medium of gas and dust, and an important but poorly understood component tentatively dubbed dark matter. The word galaxy is derived from the Greek galaxias , literally "milky", a...
between magnitudes 13 and 15 include NGC 7015, NGC 7040, NGC 7045 and NGC 7046.
Mythology
In Greek mythologyGreek mythology
Greek mythology is the body of myths and legends belonging to the ancient Greeks, concerning their gods and heroes, the nature of the world, and the origins and significance of their own cult and ritual practices. They were a part of religion in ancient Greece...
, one myth associates Equuleus with the foal Celeris (meaning "swiftness" or "speed"), who was the offspring or brother of the winged horse Pegasus
Pegasus
Pegasus is one of the best known fantastical as well as mythological creatures in Greek mythology. He is a winged divine horse, usually white in color. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. He was the brother of Chrysaor, born at a single birthing...
. Celeris was given to Castor
Castor and Pollux
In Greek and Roman mythology, Castor and Pollux or Polydeuces were twin brothers, together known as the Dioscuri . Their mother was Leda, but Castor was the mortal son of Tyndareus, king of Sparta, and Pollux the divine son of Zeus, who visited Leda in the guise of a swan...
by Mercury
Mercury (mythology)
Mercury was a messenger who wore winged sandals, and a god of trade, the son of Maia Maiestas and Jupiter in Roman mythology. His name is related to the Latin word merx , mercari , and merces...
. Other myths say that Equuleus is the horse struck from Neptune
Neptune
Neptune is the eighth and farthest planet from the Sun in the Solar System. Named for the Roman god of the sea, it is the fourth-largest planet by diameter and the third largest by mass. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times...
's trident, during the contest between him and Athena
Athena
In Greek mythology, Athena, Athenê, or Athene , also referred to as Pallas Athena/Athene , is the goddess of wisdom, courage, inspiration, civilization, warfare, strength, strategy, the arts, crafts, justice, and skill. Minerva, Athena's Roman incarnation, embodies similar attributes. Athena is...
when deciding which would be the superior. Because this section of stars rises before Pegasus
Pegasus
Pegasus is one of the best known fantastical as well as mythological creatures in Greek mythology. He is a winged divine horse, usually white in color. He was sired by Poseidon, in his role as horse-god, and foaled by the Gorgon Medusa. He was the brother of Chrysaor, born at a single birthing...
, it is often called Equus Primus, or the First Horse. Equuleus is also linked to the story of Philyra
Philyra
- Oceanid :In Greek mythology, Philyra was an Oceanid, a daughter of Oceanus and Tethys. Chiron was her son by Cronus. When she gave birth to her son, she was so disgusted by how he looked that she abandoned him at birth. She was the goddess of perfume, writing, healing, beauty and paper...
and Saturn
Saturn
Saturn is the sixth planet from the Sun and the second largest planet in the Solar System, after Jupiter. Saturn is named after the Roman god Saturn, equated to the Greek Cronus , the Babylonian Ninurta and the Hindu Shani. Saturn's astronomical symbol represents the Roman god's sickle.Saturn,...
.
Equivalents
In Chinese astronomyChinese astronomy
Astronomy in China has a very long history, with historians considering that "they [the Chinese] were the most persistent and accurate observers of celestial phenomena anywhere in the world before the Arabs."...
, the stars that correspond to Equuleus are located within the Black Tortoise of the North
Black Tortoise (Chinese constellation)
The Black Tortoise is one of the Four Symbols of the Chinese constellations. It is sometimes called the Black Warrior of the North , and is known as Xuanwu in Chinese, Genbu in Japanese, Hyeonmu in Korean and Huyền Vũ in Vietnamese. It represents the north and the winter season...
(北方玄武, Běi Fāng Xuán Wǔ).