Apus is a small
constellation in the
southern sky
The southern celestial hemisphere, also called the Southern Sky, is the southern half of the celestial sphere; that is, it lies south of the celestial equator. This arbitrary sphere, on which seemingly fixed stars form constellations, app ...
. It represents a
bird-of-paradise
The birds-of-paradise are members of the family Paradisaeidae of the order Passeriformes. The majority of species are found in eastern Indonesia, Papua New Guinea and eastern Australia. The family has 44 species in 17 genera. The members of this ...
, and its name means "without feet" in
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 ...
because the bird-of-paradise was once wrongly believed to lack feet. First depicted on a celestial globe by
Petrus Plancius
Petrus Plancius (; 1552 – 15 May 1622) was a Dutch-Flemish astronomer, cartographer and clergyman. He was born as Pieter Platevoet in Dranouter, now in Heuvelland, West Flanders. He studied theology in Germany and England. At the age of 24 he ...
in 1598, it was charted on a star atlas by
Johann Bayer in his 1603 ''
Uranometria
''Uranometria'' is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mangle (''Christophorus Mangus'') under the full title ''Uranometria: omnium asterismorum continens schemata, nova methodo delineata, a ...
''. The French explorer and astronomer
Nicolas Louis de Lacaille
Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Goo ...
charted and gave the brighter stars their
Bayer designations in 1756.
The five brightest stars are all reddish in hue. Shading the others at
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 ...
3.8 is
Alpha Apodis
Alpha Apodis (Alpha Aps, α Apodis, α Aps) is the brightest star in the southern circumpolar constellation of Apus, with an apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or ...
, an orange giant that has around 48 times the diameter and 928 times the
luminosity of the Sun. Marginally fainter is
Gamma Apodis
Gamma Apodis (γ Aps, γ Apodis) is the Bayer designation for a star in the southern circumpolar constellation of Apus. From parallax measurements, the distance to this star can be estimated as . It is visible to the naked eye with an ...
, another ageing giant star.
Delta Apodis
Delta Apodis (δ Aps, δ Apodis) is the Bayer designation for a double star in the southern constellation of Apus.
The brighter star, δ Apodis, is an M-type red giant and has an apparent magnitude that varies from magnitude +4.66 t ...
is a
double star, the two components of which are 103
arcseconds
A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of angular measurement equal to of one degree. Since one degree is of a turn (or complete rotation), one minute of arc is of a turn. The ...
apart and visible with the naked eye. Two star systems have been found to have
planets.
History
![BayerUran1661apuschamtri](https://upload.wikimedia.org/wikipedia/commons/5/58/BayerUran1661apuschamtri.jpg)
Apus was one of twelve constellations published by
Petrus Plancius
Petrus Plancius (; 1552 – 15 May 1622) was a Dutch-Flemish astronomer, cartographer and clergyman. He was born as Pieter Platevoet in Dranouter, now in Heuvelland, West Flanders. He studied theology in Germany and England. At the age of 24 he ...
from the observations of
Pieter Dirkszoon Keyser
Pieter Dirkszoon Keyser (occasionally Petrus Theodorus; – 11 September 1596) was a Dutch navigator and celestial cartographer who mapped several constellations on the southern celestial hemisphere.
Voyages and star observation
Little is ...
and
Frederick de Houtman
Frederick de Houtman ( – 21 October 1627) was a Dutch explorer, navigator, and colonial governor who sailed on the first Dutch expedition to the East Indies from 1595 until 1597, during which time he made observations of the southern ce ...
who had sailed on the first Dutch trading expedition, known as the ''
Eerste Schipvaart'', to the
East Indies
The East Indies (or simply the Indies), is a term used in historical narratives of the Age of Discovery. The Indies refers to various lands in the East or the Eastern hemisphere, particularly the islands and mainlands found in and around ...
. It first appeared on a 35-cm (14 in) diameter celestial globe published in 1598 in Amsterdam by Plancius with
Jodocus Hondius.
De Houtman included it in his southern star catalogue in 1603 under the Dutch name ''De Paradijs Voghel'', "The Bird of Paradise",
and Plancius called the constellation ''Paradysvogel Apis Indica''; the first word is
Dutch
Dutch commonly refers to:
* Something of, from, or related to the Netherlands
* Dutch people ()
* Dutch language ()
Dutch may also refer to:
Places
* Dutch, West Virginia, a community in the United States
* Pennsylvania Dutch Country
People E ...
for "bird of paradise". ''Apis'' (Latin for "bee") is assumed to have been a typographical error for ''avis'' ("bird").
After its introduction on Plancius's globe, the constellation's first known appearance in a celestial atlas was in German cartographer
Johann Bayer's ''
Uranometria
''Uranometria'' is a star atlas produced by Johann Bayer. It was published in Augsburg in 1603 by Christoph Mangle (''Christophorus Mangus'') under the full title ''Uranometria: omnium asterismorum continens schemata, nova methodo delineata, a ...
'' of 1603.
[ Bayer called it ''Apis Indica'' while fellow astronomers Johannes Kepler and his son-in-law ]Jakob Bartsch
Jakob Bartsch or Jacobus Bartschius (c. 1600 – 26 December 1633) was a German astronomer.
Biography
Bartsch was born in Lauban (Lubań) in Lusatia. He was taught how to use the astrolabe by Sarcephalus (Christopher Hauptfleisch), a librar ...
called it ''Apus'' or ''Avis Indica''. The name ''Apus'' is derived from the Greek ''apous'', meaning "without feet". This referred to the Western misconception that the bird-of-paradise had no feet, which arose because the only specimens available in the West had their feet and wings removed. Such specimens began to arrive in Europe in 1522, when the survivors of Ferdinand Magellan
Ferdinand Magellan ( or ; pt, Fernão de Magalhães, ; es, link=no, Fernando de Magallanes, ; 4 February 1480 – 27 April 1521) was a Portuguese explorer. He is best known for having planned and led the 1519 Spanish expedition to the Eas ...
's expedition brought them home. The constellation later lost some of its tail when Nicolas-Louis de Lacaille
Abbé Nicolas-Louis de Lacaille (; 15 March 171321 March 1762), formerly sometimes spelled de la Caille, was a French astronomer and geodesist who named 14 out of the 88 constellations. From 1750 to 1754, he studied the sky at the Cape of Goo ...
used those stars to establish Octans
Octans () is a faint constellation located in the deep Southern Sky. Its name is Latin for the eighth part of a circle, but it is named after the octant, a navigational instrument. Devised by French astronomer Nicolas Louis de Lacaille in 1752 ...
in the 1750s.
Characteristics
Covering 206.3 square degrees and hence 0.5002% of the sky, Apus ranks 67th of the 88 modern constellations by area. Its position in the Southern Celestial Hemisphere
The southern celestial hemisphere, also called the Southern Sky, is the southern half of the celestial sphere; that is, it lies south of the celestial equator. This arbitrary sphere, on which seemingly fixed stars form constellations, appea ...
means that the whole constellation is visible to observers south of 7°N.[ It is bordered by ]Ara
ARA may refer to:
Media and the arts
* American-Romanian Academy of Arts and Sciences
* '' Artistička Radna Akcija'', compilation album released in former Yugoslavia
* Associate of the Royal Academy, denoting membership in the British Royal Aca ...
, Triangulum Australe and Circinus to the north, Musca
Musca () is a small constellation in the deep southern sky. It was one of 12 constellations created by Petrus Plancius from the observations of Pieter Dirkszoon Keyser and Frederick de Houtman, and it first appeared on a celestial globe in ...
and Chamaeleon
Chamaeleon () is a small constellation in the deep southern sky. It is named after the chameleon, a kind of lizard. It was first defined in the 16th century.
History
Chamaeleon was one of twelve constellations created by Petrus Plancius fr ...
to the west, Octans to the south, and Pavo to the east. The three-letter abbreviation for the constellation, as adopted 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 ...
in 1922, is "Aps". The official constellation boundaries, as set by Belgian astronomer 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 −67.48° and −83.12°.
Features
Stars
Lacaille gave twelve stars Bayer designations, labelling them Alpha through to Kappa, including two stars next to each other as Delta and another two stars near each other as Kappa.[ Within the constellation's borders, there are 39 stars brighter than or equal to ]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 ...
6.5.[ Beta, Gamma and ]Delta Apodis
Delta Apodis (δ Aps, δ Apodis) is the Bayer designation for a double star in the southern constellation of Apus.
The brighter star, δ Apodis, is an M-type red giant and has an apparent magnitude that varies from magnitude +4.66 t ...
form a narrow triangle, with Alpha Apodis
Alpha Apodis (Alpha Aps, α Apodis, α Aps) is the brightest star in the southern circumpolar constellation of Apus, with an apparent magnitude
Apparent magnitude () is a measure of the brightness of a star or ...
lying to the east. The five brightest stars are all red-tinged, which is unusual among constellations.
Alpha Apodis is an orange giant
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...
of spectral type K3III located 430 ± 20 light-years away from Earth, with an apparent magnitude of 3.8. It spent much of its life as a blue-white (B-type) main sequence star before expanding, cooling and brightening as it used up its core hydrogen. It has swollen to 48 times the Sun's diameter, and shines with a luminosity approximately 928 times that of the Sun, with a surface temperature of 4312 K. Beta Apodis is an orange giant 149 ± 2 light-years away,[ with a magnitude of 4.2.][ It is around 1.84 times as massive as the Sun, with a surface temperature of 4677 K. Gamma Apodis is a ]yellow giant
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...
of spectral type G8III located 150 ± 4 light-years away,[ with a magnitude of 3.87. It is approximately 63 times as luminous the Sun, with a surface temperature of 5279 K.][ Delta Apodis is a double star, the two components of which are 103 arcseconds apart and visible through binoculars. Delta1 is a red giant star of spectral type M4III located 630 ± 30 light-years away.][ It is a semiregular variable that varies from magnitude +4.66 to +4.87,] with pulsations of multiple periods of 68.0, 94.9 and 101.7 days. Delta2 is an orange giant
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...
star of spectral type K3III, located 550 ± 10 light-years away,[ with a magnitude of 5.3. The separate components can be resolved with the naked eye.][
The fifth-brightest star is ]Zeta Apodis
Zeta Apodis, Latinized from ζ Apodis, is the Bayer designation for a star in the southern constellation of Apus. It has an apparent visual magnitude of +4.78, which is bright enough to allow it to be seen with the naked eye. The dis ...
at magnitude 4.8,[ a star that has swollen and cooled to become an orange giant of spectral type K1III, with a surface temperature of 4649 K and a luminosity 133 times that of the Sun.][ It is 300 ± 4 light-years distant.][ Near Zeta is ]Iota Apodis
Iota Apodis (ι Aps, ι Apodis) is the Bayer designation for a binary star system in the southern circumpolar constellation of Apus. It is a faint target at an apparent visual magnitude of 5.41, but still visible to the naked eye from ...
, a binary star system 1,040 ± 60 light-years distant,[ that is composed of two blue-white main sequence stars that orbit each other every 59.32 years. Of spectral types B9V and B9.5 V, they are both over three times as massive as the Sun.
]Eta Apodis
Eta Apodis, Latinized from η Apodis, is a star in the southern circumpolar constellation Apus. Based upon parallax measurements from the Hipparcos mission, it is approximately from Earth. With an apparent visual magnitude of +4.9, it ca ...
is a white main sequence star located 140.8 ± 0.9 light-years distant.[ Of apparent magnitude 4.89, it is 1.77 times as massive, 15.5 times as luminous as the Sun and has 2.13 times its radius. Aged 250 ± 200 million years old, this star is emitting an excess of 24 μm infrared radiation, which may be caused by a ]debris disk
A debris disk (American English), or debris disc (Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris di ...
of dust orbiting at a distance of more than 31 astronomical unit
The astronomical unit (symbol: au, or or AU) is a unit of length, roughly the distance from Earth to the Sun and approximately equal to or 8.3 light-minutes. The actual distance from Earth to the Sun varies by about 3% as Earth orbits ...
s from it.
Theta Apodis is a cool red giant of spectral type M7 III located 350 ± 30 light-years distant.[ It shines with a luminosity approximately 3879 times that of the Sun and has a surface temperature of 3151 K.][ A semiregular variable, it varies by 0.56 magnitudes with a period of 119 days]—or approximately 4 months.[ It is losing mass at the rate of times the mass of the Sun per year through its stellar wind. Dusty material ejected from this star is interacting with the surrounding interstellar medium, forming a ]bow shock
In astrophysics, a bow shock occurs when the magnetosphere of an astrophysical object interacts with the nearby flowing ambient plasma such as the solar wind. For Earth and other magnetized planets, it is the boundary at which the speed of th ...
as the star moves through the galaxy.[ See table 1, IRAS 14003-7633.] NO Apodis is a red giant of spectral type M3III that varies between magnitudes 5.71 and 5.95. Located 780 ± 20 light-years distant, it shines with a luminosity estimated at 2059 times that of the Sun and has a surface temperature of 3568 K.[ S Apodis is a rare R Coronae Borealis variable, an extremely hydrogen-deficient supergiant thought to have arisen as the result of the merger of two white dwarfs; fewer than 100 have been discovered as of 2012. It has a baseline magnitude of 9.7.] R Apodis is a star that was given a variable star designation
In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the Bayer designation format, with an identifying label (as described below) preceding the Latin genitive of the name of the conste ...
, yet has turned out not to be variable. Of magnitude 5.3,[ it is another orange giant.
Two star systems have had exoplanets discovered by ]doppler spectroscopy
Doppler spectroscopy (also known as the radial-velocity method, or colloquially, the wobble method) is an indirect method for finding extrasolar planets and brown dwarfs from radial-velocity measurements via observation of Doppler shifts in t ...
, and the substellar companion of a third star system—the sunlike star HD 131664—has since been found to be 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 ...
with a calculated mass of the companion to 23 times that of Jupiter (minimum of 18 and maximum of 49 Jovian masses). HD 134606 is a yellow sunlike star of spectral type G6IV that has begun expanding and cooling off the main sequence. Three planets orbit it with periods of 12, 59.5 and 459 days, successively larger as they are further away from the star. HD 137388 is another star—of spectral type K2IV—that is cooler than the Sun and has begun cooling off the main sequence. Around 47% as luminous and 88% as massive as the Sun, with 85% of its diameter, it is thought to be around 7.4 ± 3.9 billion years old. It has a planet that is 79 times as massive as the Earth and orbits its sun every 330 days at an average distance of 0.89 astronomical units (AU).
Deep-sky objects
The 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. ...
covers much of the constellation's area. Of the deep-sky objects in Apus, there are two prominent 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 ...
s— NGC 6101 and IC 4499—and a large faint nebula that covers several degrees east of Beta and Gamma Apodis. NGC 6101 is a globular cluster of apparent magnitude 9.2 located around 50,000 light-years distant from Earth, which is around 160 light-years across. Around 13 billion years old, it contains a high concentration of massive bright stars known as blue straggler
A blue straggler is a main-sequence star in an open or globular cluster that is more luminous and bluer than stars at the main sequence turnoff point for the cluster. Blue stragglers were first discovered by Allan Sandage in 1953 while perform ...
s, thought to be the result of two stars merging. IC 4499 is a loose globular cluster in the medium-far galactic halo
A galactic halo is an extended, roughly spherical component of a galaxy which extends beyond the main, visible component. Several distinct components of galaxies comprise the halo:
* the stellar halo
* the galactic corona (hot gas, i.e. a plas ...
; its apparent magnitude is 10.6.
The galaxies in the constellation are faint.[ IC 4633 is a very faint spiral galaxy surrounded by a vast amount of Milky Way line-of-sight integrated flux nebulae—large faint clouds thought to be lit by large numbers of stars.][
]
See also
* Dutch celestial cartography in the Age of Exploration
The history of cartography refers to the development and consequences of cartography, or mapmaking technology, throughout human history. Maps have been one of the most important human inventions for millennia, allowing humans to explain and navig ...
( Early systematic mapping of the far southern sky, c. 1595–1599)
*
* IAU-recognized constellations
Notes
References
External links
The Deep Photographic Guide to the Constellations: Apus
{{DEFAULTSORT:Apus
Southern constellations
Constellations listed by Petrus Plancius
Dutch celestial cartography in the Age of Discovery
Astronomy in the Dutch Republic
1590s in the Dutch Republic