Epsilon Capricorni, Latinized from ε Capricorni, is a possible binary star system in the constellation

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 ...

. It has the traditional star name Kastra, meaning "fort" or "

military camp A military camp or bivouac is a semi-permanent military base, for the lodging of an army. Camps are erected when a military force travels away from a major installation or fort during training or military operations, operations, and often have t ...

" 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 ...

. 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 3.09 mas as seen from the Earth, the star is located about 1,060

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 can be seen with the naked eye, having a combined

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 4.62. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of v ...

, (), meaning '' Line of Ramparts'', refers to an asterism consisting of ε Capricorni, κ Capricorni, γ Capricorni, δ Capricorni, ι Aquarii, σ Aquarii, λ Aquarii, φ Aquarii,

27 Piscium 27 Piscium is a binary star system in the zodiac constellation of Pisces. It is visible to the naked eye with an apparent visual magnitude of 4.88. Based upon an annual parallax shift of , it is located about 234 light years away. ...

29 Piscium 9 (nine) is the natural number following and preceding . Evolution of the Arabic digit In the beginning, various Indians wrote a digit 9 similar in shape to the modern closing question mark without the bottom dot. The Kshatrapa, Andhra a ...

33 Piscium 33 Piscium is a binary star system in the zodiac constellation of Pisces. It is visible to the naked eye with an apparent visual magnitude of 4.61. The distance to this system, as determined from an annual parallax shift of , is about ...

and 30 Piscium. 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 ε Capricorni itself is (, en, the Second Star of Line of Ramparts.) EpsilonCapLightCurve

The binary system has an

orbital period The orbital period (also revolution period) is the amount of time a given astronomical object takes to complete one orbit around another object. In astronomy, it usually applies to planets or asteroids orbiting the Sun, moons orbiting planets ...

of 129 days. The primary, component Aa, is a

Be star Be stars are a heterogeneous set of stars with B spectral types and emission lines. A narrower definition, sometimes referred to as ''classical Be stars'', is a non-supergiant B star whose spectrum has, or had at some time, one or more Balmer e ...

that is surrounded by ionized gas that is producing the

emission line A spectral line is a dark or bright line in an otherwise uniform and continuous spectrum, resulting from emission or absorption of light in a narrow frequency range, compared with the nearby frequencies. Spectral lines are often used to iden ...

s in the spectrum. This circumstellar shell is inclined by 80° to the line of sight from the Earth. The system is undergoing both short term and long term variations in luminosity, with the short period variations showing a phase cycle of 1.03 days. It is classified as a

Gamma Cassiopeiae variable A Gamma Cassiopeiae variable (γ Cassiopeiae variable) is a type of variable star, named for its prototype γ Cassiopeiae. Variability γ Cassiopeiae variables show irregular changes in brightness on a timescale of decades. These typically have ...

with an amplitude of 0.16 in magnitude. Epsilon Capricorni Aa is a blue-white hued B-type main sequence star 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 B2.5 Vpe and a visual magnitude of +4.62. It has 7.6 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 4.8 times the Sun's radius. The star is spinning 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 225 km/s. This is giving it an

oblate In Christianity (especially in the Roman Catholic, Orthodox, Anglican and Methodist traditions), an oblate is a person who is specifically dedicated to God or to God's service. Oblates are individuals, either laypersons or clergy, normally li ...

shape with an

equatorial bulge An equatorial bulge is a difference between the equatorial and polar diameters of a planet, due to the centrifugal force exerted by the rotation about the body's axis. A rotating body tends to form an oblate spheroid rather than a sphere. On Ear ...

that is 7% larger than the polar radius. The system has two visual companions. Component B is a visual magnitude 10.11 star at an

angular separation Angular distance \theta (also known as angular separation, apparent distance, or apparent separation) is the angle between the two sightlines, or between two point objects as viewed from an observer. Angular distance appears in mathematics (in pa ...

of 65.8

arc second 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 nau ...

s along a

position angle In astronomy, position angle (usually abbreviated PA) is the convention for measuring angles on the sky. The International Astronomical Union defines it as the angle measured relative to the north celestial pole (NCP), turning positive into the ...

of 46°, as of 2013. Component C with visual magnitude of 14.1 lies at an angular separation of 62.7 arc seconds along a position angle of 164°, as of 1999. Both stars are likely to be unrelated and at different distances to Epsilon Capricorni.

References

External links

* * {{DEFAULTSORT:Epsilon Capricorni B-type main-sequence stars Gamma Cassiopeiae variable stars Binary stars Capricornus (constellation) Castra Capricorni, Epsilon Durchmusterung objects Capricorni, 39 205637 105723 8260 de:Castra