Capella (star)
Encyclopedia
Capella is the brightest star in the constellation
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....

 Auriga
Auriga (constellation)
Auriga is a constellation in the northern sky. Its name is Latin for 'charioteer' and its stars form a shape that has been associated with the pointed helmet of a charioteer. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains among the 88 modern...

, the sixth brightest star in the night sky and the third brightest star in the northern celestial hemisphere
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...

, after Arcturus and Vega
Vega
Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus...

. Although it appears to be a single star to the naked eye, it is actually a star system
Star system
A star system or stellar system is a small number of stars which orbit each other, bound by gravitational attraction. A large number of stars bound by gravitation is generally called a star cluster or galaxy, although, broadly speaking, they are also star systems.-Binary star systems:A stellar...

 of four stars in two binary pair
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...

s. The first pair consists of two bright, large type-G
Stellar classification
In astronomy, stellar classification is a classification of stars based on their spectral characteristics. The spectral class of a star is a designated class of a star describing the ionization of its chromosphere, what atomic excitations are most prominent in the light, giving an objective measure...

 giant star
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...

s, both with a radius around 10 times the Sun's, in close orbit around each other. These two stars are thought to be cooling and expanding on their way to becoming red giant
Red giant
A red giant is a luminous giant star of low or intermediate mass in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower...

s. The second pair, around 10,000 astronomical unit
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

s from the first, consists of two faint, small and relatively cool red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....

s. The Capella system is relatively close, at only 42.2 ly from Earth.

System

The Capella system consists of a bright binary pair
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...

 of giant star
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...

s, orbiting at some distance from a fainter binary pair of red dwarf
Red dwarf
According to the Hertzsprung-Russell diagram, a red dwarf star is a small and relatively cool star, of the main sequence, either late K or M spectral type....

s. The system is a member of the Hyades moving group, a group of stars moving in the same direction as the Hyades cluster.

Bright binary pair

Capella was first announced to be binary in 1899, based on spectroscopic observations. Known as "The Interferometrist's Friend", it was first resolved interferometrically
Interferometry
Interferometry refers to a family of techniques in which electromagnetic waves are superimposed in order to extract information about the waves. An instrument used to interfere waves is called an interferometer. Interferometry is an important investigative technique in the fields of astronomy,...

 in 1919 by John Anderson and Francis Pease at Mount Wilson Observatory
Mount Wilson Observatory
The Mount Wilson Observatory is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715 foot peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles...

, who published an orbit in 1920 based on their observations. This was the first interferometric measurement of any object outside the Solar System
Solar System
The Solar System consists of the Sun and the astronomical objects gravitationally bound in orbit around it, all of which formed from the collapse of a giant molecular cloud approximately 4.6 billion years ago. The vast majority of the system's mass is in the Sun...

. A high-precision orbit was published in 1994 based on observations by the Mark III Stellar Interferometer
Mark III Stellar Interferometer
The Mark III Stellar Interferometer was a long-baseline optical astronomical interferometer, located at the Mount Wilson Observatory, California, United States. It had a maximum baseline of 32 meters and operated in wavelengths between 450 and 800 nm...

, again at Mount Wilson Observatory. Capella also became the first astronomical object to be imaged by a separate element optical interferometer when it was imaged by the Cambridge Optical Aperture Synthesis Telescope
Cambridge Optical Aperture Synthesis Telescope
COAST, the Cambridge Optical Aperture Synthesis Telescope, is a multi-element optical astronomical interferometer with baselines of up to 100 metres, which uses aperture synthesis to observe stars with angular resolution as high as one thousandth of one arcsecond COAST, the Cambridge Optical...

 in September 1995.

The bright binary pair of Capella consists of two type-G giant star
Giant star
A giant star is a star with substantially larger radius and luminosity than a main sequence star of the same surface temperature. Typically, giant stars have radii between 10 and 100 solar radii and luminosities between 10 and 1,000 times that of the Sun. Stars still more luminous than giants are...

s. The first, primary, star has an surface temperature
Effective temperature
The effective temperature of a body such as a star or planet is the temperature of a black body that would emit the same total amount of electromagnetic radiation...

 of approximately 4900 K
Kelvin
The kelvin is a unit of measurement for temperature. It is one of the seven base units in the International System of Units and is assigned the unit symbol K. The Kelvin scale is an absolute, thermodynamic temperature scale using as its null point absolute zero, the temperature at which all...

, a radius of approximately 12 solar radii, a mass of approximately 2.7 solar masses, and a luminosity
Luminosity
Luminosity is a measurement of brightness.-In photometry and color imaging:In photometry, luminosity is sometimes incorrectly used to refer to luminance, which is the density of luminous intensity in a given direction. The SI unit for luminance is candela per square metre.The luminosity function...

, measured over all wavelengths, approximately 79 times that of the Sun
Sun
The Sun is the star at the center of the Solar System. It is almost perfectly spherical and consists of hot plasma interwoven with magnetic fields...

. The other, secondary, star has a surface temperature of approximately 5700 K, a radius of approximately 9 solar radii, a mass of approximately 2.6 solar masses, and a luminosity, again measured over all wavelengths, approximately 78 times that of the Sun. Although the primary is the brighter star when considering radiation at all wavelengths, it is the fainter when observed in visible light, with an apparent visual magnitude of approximately 0.91, compared to the secondary's apparent visual magnitude of 0.76.

The pair is a non-eclipsing binary—that is, as seen from Earth, neither star passes in front of the other. The two components orbit each other at a distance of around 100 million km and an orbital period of approximately 104 days. The stars were probably of spectral class A during their main-sequence lifetime, similar to Vega
Vega
Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus...

; they are now expanding, cooling, and brightening to become red giants, a process that will take a few million years. It is thought that the more massive star of the pair has begun fusing helium
Helium
Helium is the chemical element with atomic number 2 and an atomic weight of 4.002602, which is represented by the symbol He. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas that heads the noble gas group in the periodic table...

 to carbon
Carbon
Carbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...

 and oxygen
Oxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...

 at its center, a process that has not yet begun for the less massive star.

X-ray source

Two Aerobee-Hi rocket flights on September 20, 1962, and March 15, 1963, apparently detected and confirmed an X-ray source in Auriga at RA
Right ascension
Right ascension is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. The other coordinate is the declination.-Explanation:...

  Dec
Declination
In astronomy, declination is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. Declination in astronomy is comparable to geographic latitude, but projected onto the celestial sphere. Declination is measured in degrees north and...

 . It was identified as Capella which is in the error box. Capella was much more readily detected on the second rocket flight.

Stellar X-ray astronomy started on April 5, 1974, with the detection of X-rays from Capella. A rocket flight on that date briefly calibrated its attitude control system when a star sensor pointed the payload axis at Capella (α Aur). During this period, X-rays in the range 0.2–1.6 keV were detected by an X-ray reflector system co-aligned with the star sensor. The X-ray luminosity (Lx) of ~1024 W (1031 erg s−1) is four orders of magnitude above the Sun's X-ray luminosity.

Capella is a source of X-ray
X-ray
X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

s, thought to be primarily from the corona
Corona
A corona is a type of plasma "atmosphere" of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph...

 of the more massive star. Capella is ROSAT
ROSAT
ROSAT was a German Aerospace Center-led satellite X-ray telescope, with instruments built by Germany, the UK and the US...

 X-ray source 1RXS J051642.2+460001. The high temperature of Capella's corona as obtained from the first coronal X-ray spectrum of Capella using HEAO 1 required magnetic confinement unless it was a free-flowing coronal wind.

Companion binary

In 1914, R. Furuhjelm observed that the spectroscopic binary mentioned above had a faint companion star, which, as its proper motion
Proper motion
The proper motion of a star is its angular change in position over time as seen from the center of mass of the solar system. It is measured in seconds of arc per year, arcsec/yr, where 3600 arcseconds equal one degree. This contrasts with radial velocity, which is the time rate of change in...

 was similar to that of the spectroscopic binary, was probably physically bound to it. In 1936, Carl L. Stearns observed that this companion appeared to be double itself; this was later confirmed by G. P. Kuiper. This double companion star is a binary system
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...

 of red dwarfs, thought to be separated from the pair of G-type giants by a distance of around 10,000 AU
Astronomical unit
An astronomical unit is a unit of length equal to about or approximately the mean Earth–Sun distance....

. Although this pair has only been observed to cover approximately 30° of its orbit, a rough, preliminary orbit has been computed, giving an orbital period of approximately 400 years.

Visibility

Capella appears to be a rich yellow color. It is the brightest star in the constellation
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....

 Auriga
Auriga (constellation)
Auriga is a constellation in the northern sky. Its name is Latin for 'charioteer' and its stars form a shape that has been associated with the pointed helmet of a charioteer. It was one of the 48 constellations listed by the 2nd century astronomer Ptolemy, and remains among the 88 modern...

, the sixth brightest star in the night sky, the third brightest star in the northern celestial hemisphere
Celestial sphere
In astronomy and navigation, the celestial sphere is an imaginary sphere of arbitrarily large radius, concentric with the Earth and rotating upon the same axis. All objects in the sky can be thought of as projected upon the celestial sphere. Projected upward from Earth's equator and poles are the...

 (after Arcturus and Vega
Vega
Vega is the brightest star in the constellation Lyra, the fifth brightest star in the night sky and the second brightest star in the northern celestial hemisphere, after Arcturus...

), and the fourth brightest star visible to the naked eye from the latitude 40° N. It is closer to the north celestial pole than any other first magnitude star (Polaris
Polaris
Polaris |Alpha]] Ursae Minoris, commonly North Star or Pole Star, also Lodestar) is the brightest star in the constellation Ursa Minor. It is very close to the north celestial pole, making it the current northern pole star....

 is only second magnitude). It lies a few degrees to the northeast from the triangle of stars known as "The Kids" (ε
Epsilon Aurigae
Epsilon Aurigae is a star in the constellation Auriga. It is traditionally known as Almaaz, Haldus, or Al Anz. Epsilon Aurigae is an unusual eclipsing binary system comprising an F0 supergiant and a companion which is generally accepted to be a huge dark disk orbiting an unknown object, possibly a...

, ζ
Zeta Aurigae
Zeta Aurigae is a star in the constellation Auriga. It has the traditional names Haedus and Sadatoni . It is one of the two hædi of the she-goat Capella, the other being Hoedus II, Eta Aurigae...

, and η Aurigae
Eta Aurigae
Eta Aurigae is a star in the constellation Auriga. Along with ζ Aurigae it represents one of the Kids of the she-goat Capella, from which it gets its Latin traditional name Hoedus II or Haedus II, from the Latin hædus "kid"; Zeta Aurigae is Hoedus I...

).

Capella's northern declination is such that it is actually invisible south of latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

 44°S – this includes southernmost New Zealand, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 and Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

 as well as the Falkland Islands
Falkland Islands
The Falkland Islands are an archipelago in the South Atlantic Ocean, located about from the coast of mainland South America. The archipelago consists of East Falkland, West Falkland and 776 lesser islands. The capital, Stanley, is on East Falkland...

. Conversely it is circumpolar
Circumpolar star
A circumpolar star is a star that, as viewed from a given latitude on Earth, never sets , due to its proximity to one of the celestial poles...

 north of 44°north: for the whole of the United Kingdom and Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...

, most of Canada and the northernmost United States, the star never sets.

Capella was the brightest star in the night sky from 210,000 years ago to 160,000 years ago, at about -1.8 in magnitude. At -1.1, Aldebaran
Aldebaran
Aldebaran is a red giant star located about 65 light years away in the zodiac constellation of Taurus. With an average apparent magnitude of 0.87 it is the brightest star in the constellation and is one of the brightest stars in the nighttime sky...

 was brightest before this period, and it and Capella were situated rather close to each other and served as boreal polestars at the time.

Etymology and cultural significance

The name Capella (English: small female goat) is from Latin, and is a diminutive of the Latin Capra (English: female goat). Capella traditionally marks the left shoulder of the constellation's eponymous charioteer, or, according to the 2nd century astronomer Ptolemy's Almagest
Almagest
The Almagest is a 2nd-century mathematical and astronomical treatise on the apparent motions of the stars and planetary paths. Written in Greek by Claudius Ptolemy, a Roman era scholar of Egypt,...

, the goat that the charioteer is carrying. In Roman mythology
Roman mythology
Roman mythology is the body of traditional stories pertaining to ancient Rome's legendary origins and religious system, as represented in the literature and visual arts of the Romans...

, the star represented the goat Amalthea
Amalthea (mythology)
In Greek mythology, Amalthea or Amaltheia is the most-frequently mentioned foster-mother of Zeus. Her name in Greek is clearly an epithet, signifying the presence of an earlier nurturing goddess, whom the Hellenes, whose myths we know, knew to be located in Crete, where Minoans may have called...

 that suckled Jupiter. It was this goat whose horn, after accidentally being broken off by Jupiter, was transformed into the Cornucopia
Cornucopia
The cornucopia or horn of plenty is a symbol of abundance and nourishment, commonly a large horn-shaped container overflowing with produce, flowers, nuts, other edibles, or wealth in some form...

, or "horn of plenty", which would be filled with whatever its owner desired.
Astrologically
Astrology
Astrology consists of a number of belief systems which hold that there is a relationship between astronomical phenomena and events in the human world...

, Capella portends civic and military
Military
A military is an organization authorized by its greater society to use lethal force, usually including use of weapons, in defending its country by combating actual or perceived threats. The military may have additional functions of use to its greater society, such as advancing a political agenda e.g...

 honors and wealth
Wealth
Wealth is the abundance of valuable resources or material possessions. The word wealth is derived from the old English wela, which is from an Indo-European word stem...

. In the Middle Ages
Middle Ages
The Middle Ages is a periodization of European history from the 5th century to the 15th century. The Middle Ages follows the fall of the Western Roman Empire in 476 and precedes the Early Modern Era. It is the middle period of a three-period division of Western history: Classic, Medieval and Modern...

, it was considered a Behenian fixed star
Behenian fixed star
The Behenian fixed stars are a selection of fifteen stars considered especially useful for magical applications in the medieval astrology of Europe and the Arab world. Their name derives from Arabic bahman, "root," as each was considered a source of astrological power for one or more planets...

, with the stone sapphire
Sapphire
Sapphire is a gemstone variety of the mineral corundum, an aluminium oxide , when it is a color other than red or dark pink; in which case the gem would instead be called a ruby, considered to be a different gemstone. Trace amounts of other elements such as iron, titanium, or chromium can give...

 and the plants horehound, mint, mugwort, and mandrake as attributes. Cornelius Agrippa listed its kabbalistic sign with the name Hircus (Latin for goat).

In medieval accounts, it also has the uncommon name Alhajoth (also spelled Alhaior, Althaiot, Alhaiset, Alhatod, Alhojet, Alanac, Alanat, Alioc), which (especially the last) may be a corruption of its Arabic name, , al-cayyūq. cAyyūq has no clear significance in Arabic, but may be an Arabized form of the Greek αίξ aiks "goat"; cf. the modern Greek Αίγα Aiga, the feminine of goat.

Capella is thought to be mentioned in an Akkadian
Akkadian language
Akkadian is an extinct Semitic language that was spoken in ancient Mesopotamia. The earliest attested Semitic language, it used the cuneiform writing system derived ultimately from ancient Sumerian, an unrelated language isolate...

 inscription dating to the 20th century BC
20th century BC
The 20th century BC is a century which lasted from the year 2000 BC to 1901 BC.-Events:* 2000 BC: Arrival of the ancestors of the Latins in Italy.* 2000 BC: Town of Mantua was presumably founded.* 2000 BC: Stonehenge is believed to have been completed....

. It is sometimes called the Shepherd's Star in English literature.
Other names used by other cultures include: in Arabic, Al-Rākib "the driver", a translation of the Greek; in Quechua, Colca; and in Hawaiian
Hawaiian language
The Hawaiian language is a Polynesian language that takes its name from Hawaii, the largest island in the tropical North Pacific archipelago where it developed. Hawaiian, along with English, is an official language of the state of Hawaii...

, Hoku-lei (English: Star-wreath).
To the Bedouin
Negev Bedouins
The Negev Bedouin are traditionally pastoral semi-nomadic Arab tribes indigenous to the Negev region in Israel, who hold close ties to the Bedouin of the Sinai Peninsula. The move away from their traditional lifestyle in modern times has led to sedentarization.Estimated to number some 160,000,...

 of the Negev
Negev
The Negev is a desert and semidesert region of southern Israel. The Arabs, including the native Bedouin population of the region, refer to the desert as al-Naqab. The origin of the word Neghebh is from the Hebrew root denoting 'dry'...

 and Sinai, Capella al-‘Ayyūq ath-Thurayyā "Capella of the Pleiades
Pleiades (star cluster)
In astronomy, the Pleiades, or Seven Sisters , is an open star cluster containing middle-aged hot B-type stars located in the constellation of Taurus. It is among the nearest star clusters to Earth and is the cluster most obvious to the naked eye in the night sky...

", from its role as pointing out the position of that asterism.

In Hindu mythology
Hindu mythology
Hindu religious literature is the large body of traditional narratives related to Hinduism, notably as contained in Sanskrit literature, such as the Sanskrit epics and the Puranas. As such, it is a subset of Nepali and Indian culture...

, Capella was seen as the heart of Brahma
Brahma
Brahma is the Hindu god of creation and one of the Trimurti, the others being Vishnu and Shiva. According to the Brahma Purana, he is the father of Mānu, and from Mānu all human beings are descended. In the Ramayana and the...

, Brahma Ridaya. In traditional Chinese astronomy, Capella was part of the asterism (Simplified Chinese: ; ; English: Five Chariots
Five Chariots
Five Chariots is a constellation in Chinese astronomy.-Introduction:A five-star Chinese constellation that contains Auriga plus Beta Tauri. Also known as Gosha.-Stars:* Iota Aurigae* Alpha Aurigae* Beta Aurigae...

), which consisted of Capella together with β
Beta Aurigae
Beta Aurigae , traditionally named Menkalinan, is a white subgiant ternary star system approximately 85 light-years away in the constellation Auriga.- Nomenclature :...

, ι
Iota Aurigae
Iota Aurigae is a star in the constellation Auriga. It has the traditional name Al Kab, short for Kabdhilinan, from the Arabic الكعب ذي العنان al-kacb ðīl-cinān "the ankle of the rein holder "...

, and θ Aurigae
Theta Aurigae
Theta Aurigae is a binary star in the constellation Auriga. It is approximately 173 light-years from Earth. Rarely used proper names for this star include Bogardus and Mahasim, the latter from the Arabic المِعْصَم al-micşam "wrist" , which was also used for Eta Aurigae.The primary, θ Aurigae A,...

, as well as β Tauri. Since it was the second star in this asterism, it has the name (Simplified Chinese: ; ; English: Second of the Five Chariots). In Australian Aboriginal mythology
Australian Aboriginal astronomy
Australian Aboriginal astronomy is a name given to indigenous Australian culture relating to astronomical subjects — such as the Sun and Moon, the stars, planets, and the Milky Way, and their motions on the sky...

 for the Booroung people of Victoria, Capella was Purra, the kangaroo, pursued and killed by the nearby Gemini twins, Yurree (Castor
Castor (star)
Castor is the second brightest star in the constellation Gemini and one of the brightest stars in the night sky. Although it has the Bayer designation "alpha", it is actually fainter than Beta Geminorum...

) and Wanjel (Pollux
Pollux (star)
Pollux is an orange giant star approximately 34 light-years from the Earth in the constellation of Gemini . Pollux is the brightest star in the constellation, brighter than Castor...

).

Capella as the name

and USNS Capella (T-AKR 293), both of United States navy ships.
  • Mazda Capella
    Mazda Capella
    The second generation rear-wheel drive Capella was available between 1978 and 1982, in both sedan and coupe forms. It was known on export markets as the Mazda 626, with the exception of the United Kingdom, where it was called the Mazda Montrose, the name was changed to honour the local Mazda...

    , a model of automobile manufactured by Mazda
    Mazda
    is a Japanese automotive manufacturer based in Fuchū, Aki District, Hiroshima Prefecture, Japan.In 2007, Mazda produced almost 1.3 million vehicles for global sales...


Visual companions

In addition to the stars mentioned above, Capella has six additional visual companions
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...

—that is, stars which appear to be close to Capella in the sky. However, they are not thought to be physically close to Capella. They are shown in the table below.

See also

  • Capella in fiction

External links

  • HR 1708, catalog entry, Bright Star Catalogue
    Bright Star Catalogue
    The Bright Star Catalogue, also known as the Yale Catalogue of Bright Stars or Yale Bright Star Catalogue, is a star catalogue that lists all stars of stellar magnitude 6.5 or brighter, which is roughly every star visible to the naked eye from Earth. It is currently available online in its 5th...

    .
  • GJ 194, catalog entry, Preliminary Version of the Third Catalogue of Nearby Stars, W. Gliese and H. Jahreiss, 1991, CDS
    Centre de Données astronomiques de Strasbourg
    The Centre de données astronomiques de Strasbourg is a data hub which collects and distributes astronomical information. It was established in 1972 under the name Centre de Données Stellaires...

     ID V/70A.
  • Capella, image at Aladin
    Aladin Sky Atlas
    Aladin is an interactive software sky atlas allowing the user to visualize digitized astronomical images, superimpose entries from astronomical catalogues or databases, and interactively access related data and information from the SIMBAD database, the VizieR service and other archives for all...

    .
  • Images of the bright binary pair from [ftp://ftp.mrao.cam.ac.uk/pub/coast/capella95sep13blacknwhite.gif 13 September 1995] and [ftp://ftp.mrao.cam.ac.uk/pub/coast/capella95sep28blacknwhite.gif 28 September 1995] (note fainter blobs are just noise)
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