Theta Capricorni, Latinized from θ Capricorni, is a white-hued

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

in the southern constellation of

Capricornus Capricornus is one of the constellations of the zodiac. Its name is Latin for "horned goat" or "goat horn" or "having horns like a goat's", and it is commonly represented in the form of a sea goat: a mythical creature that is half goat, half fi ...

, positioned 0.58° south of the

ecliptic The ecliptic or ecliptic plane is the orbital plane of the Earth around the Sun. From the perspective of an observer on Earth, the Sun's movement around the celestial sphere over the course of a year traces out a path along the ecliptic agai ...

. Sometimes, this star is called by the name Dorsum, meaning ''the back (of the goat)'' in

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 ...

. It can be seen with the naked eye, having an

apparent visual 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 lig ...

of +4.07. Based upon an annual

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby object ...

shift of 20.11 mas as seen from the Earth, the star is about 162

light year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared rad ...

. It is drifting closer with a

radial velocity The radial velocity or line-of-sight velocity, also known as radial speed or range rate, of a target with respect to an observer is the rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

of −11 km/s. This is an ordinary

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

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

of A1 V. Radial velocity variations indicate it may be a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in ...

system, but when the system was examined in the

infrared Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from aroun ...

, no companion was detected. Theta Capricorni has an estimated 2.24 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

and around 2.7 times the Sun's radius. It is 152 million years old and is spinning fairly rapidly with a

projected rotational velocity Stellar rotation is the angular motion of a star about its axis. The rate of rotation can be measured from the spectrum of the star, or by timing the movements of active features on the surface. The rotation of a star produces an equatorial bulge ...

of 104 km/s. The star is radiating 65 times the

solar luminosity The solar luminosity (), is a unit of radiant flux ( power emitted in the form of photons) conventionally used by astronomers to measure the luminosity of stars, galaxies and other celestial objects in terms of the output of the Sun. One nomin ...

from its

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

at an

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. Effective temperature is often used as an estimate of a body's surface temperature ...

of around 10,000 K.

Night viewing

The star or star system is almost eclipsed by the sun on about 3 February, when it will figure behind the sun's corona if there is a full solar eclipse. Thus the star can be viewed the whole night, crossing the sky, in early August (in the current epoch).

Chinese name

In Chinese, (), meaning '' Twelve States'', refers to an asterism which represents twelve ancient states in the

Spring and Autumn period The Spring and Autumn period was a period in Chinese history from approximately 770 to 476 BC (or according to some authorities until 403 BC) which corresponds roughly to the first half of the Eastern Zhou period. The period's name derives fr ...

and the

Warring States period The Warring States period () was an era in ancient Chinese history characterized by warfare, as well as bureaucratic and military reforms and consolidation. It followed the Spring and Autumn period and concluded with the Qin wars of conquest ...

, consisting of θ Capricorni,

φ Capricorni Phi Capricorni (φ Cap, φ Capricorni) is a solitary star in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +5.16. Based upon an annual parallax shift of 5.07 mas as se ...

, ι Capricorni, 38 Capricorni, 35 Capricorni,

36 Capricorni 36 Capricorni is a single, yellow-hued star in the southern constellation of Capricornus. It is visible to the naked eye with an apparent visual magnitude of +4.50. The distance to this star, as determined from an annual parallax shift ...

, χ Capricorni,

30 Capricorni This is the list of notable stars in the constellation Capricornus, sorted by decreasing brightness. See also * List of stars by constellation References * * * * * * * {{Stars of Capricornus *List Capricornus Capricornus is one of t ...

33 Capricorni 33 may refer to: *33 (number) *33 BC *AD 33 *1933 * 2033 Music * ''33'' (Luis Miguel album) (2003) * ''33'' (Southpacific album) (1998) * ''33'' (Wanessa album) (2016) *"33 'GOD'", a 2016 song by Bon Iver * "Thirty-Three" (song), a 1995 song by t ...

, ζ Capricorni,

19 Capricorni Nineteen or 19 may refer to: * 19 (number), the natural number following 18 and preceding 20 * one of the years 19 BC, AD 19, 1919, 2019 Films * ''19'' (film), a 2001 Japanese film * ''Nineteen'' (film), a 1987 science fiction film Music ...

, 26 Capricorni, 27 Capricorni, 20 Capricorni, η Capricorni and 21 Capricorni. Consequently, the

Chinese name Chinese names or Chinese personal names are names used by individuals from Greater China and other parts of the Chinese-speaking world throughout East and Southeast Asia (ESEA). In addition, many names used in Japan, Korea and Vietnam are oft ...

for θ Capricorni itself is (, en, the First Star of Qin), meaning that this star (together with

) and δ Serpentis in '' Right Wall of Heavenly Market Enclosure'' (asterism)) represents the state Qin () (or Tsin)

References

{{DEFAULTSORT:Theta Capricorni A-type main-sequence stars Binary stars Capricorni, Theta Capricornus (constellation) Durchmusterung objects Capricorni, 23 200761 104139 8075