Gamma Capricorni or γ Capricorni, formally named Nashira (), is a

giant star A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moo ...

in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

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 ...

. Based on

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 objects ...

measurements obtained during the

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions of celestial obj ...

mission, it is located at a distance of approximately 157

light-years 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 ...

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 radi ...

. The star 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 temporal rate of change, rate of change of the distance or Slant range, range between the two points. It is e ...

of −31 km/s. It is 2.56 degrees 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 again ...

, so it can be occulted by the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

, and (rarely) by planets.

Nomenclature

''γ Capricorni'' ( Latinised to ''Gamma Capricorni'') is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

. It bore the traditional name ''Nashira'', derived from the

Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

سعد ناشرة ''sa'd nashirah'' "the lucky one" or "bearer of good news". In 2016, 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 ...

organized a

Working Group on Star Names The International Astronomical Union (IAU) established a Working Group on Star Names (WGSN) in May 2016 to catalog and standardize proper names for stars for the international astronomical community. It operates under Division C – Education ...

(WGSN) to catalogue and standardize proper names for stars. The WGSN approved the name ''Nashira'' for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names. 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 ...

, (), meaning '' Line of Ramparts'', refers to an asterism consisting of Gamma Capricorni,

Kappa Capricorni Kappa Capricorni (κ Cap, κ Capricorni) is a solitary star in the constellation Capricornus. It is visible to the naked eye with an apparent visual magnitude of +4.73. Based upon an annual parallax shift of 11.09 mas as seen from ...

Epsilon Capricorni Epsilon Capricorni, Latinized from ε Capricorni, is a possible binary star system in the constellation Capricornus. It has the traditional star name Kastra, meaning "fort" or "military camp" in Latin. Based upon an annual parallax shi ...

Delta Capricorni Delta Capricorni, or δ Capricorni, is a binary star located 38,7 light-years from the Sun in the constellation of Capricornus (the Sea Goat). The system consists of an eclipsing binary, Delta Capricorni A, and two visual companions tha ...

Iota Aquarii Iota Aquarii, Latinised from ι Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with an apparent magnitude of +4.279. Based upon parallax measurement ...

Sigma Aquarii Sigma Aquarii, Latinized from σ Aquarii, is a double star in the equatorial constellation of Aquarius, positioned about 1.3° to the south of the ecliptic. Due to its proximity to the ecliptic, this star is subject to occultation by t ...

Lambda Aquarii Lambda Aquarii, informally known as Hydor (), is a variable star in the equatorial constellation of Aquarius. The name is Latinized from the Bayer designation λ Aquarii. The apparent visual magnitude of this star ranges from 3.57 down ...

Phi Aquarii Phi Aquarii, Latinized from φ Aquarii, is the Bayer designation for a binary star system in the equatorial constellation of Aquarius. It is visible to the naked eye with a combined apparent visual magnitude of +4.223. Parallax measu ...

, 27 Piscium, 29 Piscium, 33 Piscium 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 often a ...

for Gamma Capricorni itself is (, en, the Third Star of Line of Ramparts).

Namesake

Nashira (AK-85) was a

United States Navy The United States Navy (USN) is the maritime service branch of the United States Armed Forces and one of the eight uniformed services of the United States. It is the largest and most powerful navy in the world, with the estimated tonnage ...

ship, though it was never commissioned and never bore the USS designation.

Properties

γ Capricorni is classified as a hot chemically peculiar

Am star An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc, strontium, zirconium, and barium, and deficiencies of others, such as ca ...

with a mean

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 li ...

of +3.67. The

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...

displays abundance anomalies of the elements strontium, chromium, and europium. It was first classified as an Am star in 1965 by K. Osawa, but in 1974 C. Bertaud and M. Floquet found it to be an

Ap star Ap and Bp stars are chemically peculiar stars (hence the "p") of spectral types A and B which show overabundances of some metals, such as strontium, chromium and europium. In addition, larger overabundances are often seen in praseodymium and neodym ...

with a strontium abundance anomaly. In 1998, F. A. Catalano and associates found a slight variability in the infrared J band with a period of 2.78 days, which suggests the Ap classification is correct. However, no

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

is detected, which points to the Am classification, as does the infrared spectrum. The star displays large radial velocity variations, which could be explained by

star spot Starspots are stellar phenomena, so-named by analogy with sunspots. Spots as small as sunspots have not been detected on other stars, as they would cause undetectably small fluctuations in brightness. The commonly observed starspots are in gene ...

s and rotation. Alternatively it may be a double-lined

spectroscopic binary A binary star is a system of two star, stars that are gravity, 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 separa ...

viewed from nearly pole-on. This star is classified as an α² Canum Venaticorum type

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as ...

and its brightness varies by 0.03 magnitudes. It has 2.44 times the mass and 2.35 times the radius of the Sun. O. J. Eggen included it as a member of the

Hyades Stream The Hyades Stream (or Hyades moving group) is a large collection of scattered stars that also share a similar trajectory with the Hyades Cluster. In 1869, Richard A. Proctor observed that numerous stars at large distances from the Hyades share a ...

References

External links

* {{DEFAULTSORT:Gamma Capricorni F-type main-sequence stars Am stars Alpha2 Canum Venaticorum variables Hyades Stream Capricorni, Gamma Capricornus (constellation) Durchmusterung objects Capricorni, 40 206088 106985 8278 Nashira