Delta Aquarii
   HOME

TheInfoList



OR:

Delta Aquarii is a
binary star A binary star or binary star system 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 as separate stars us ...
system 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 first constellati ...
of Aquarius. Its identifier is a
Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...
that is Latinized from δ Aquarii, and abbreviated Delta Aqr or δ Aqr, respectively. This system has the official name Skat, pronounced . It is the third-brightest star in Aquarius with an
apparent visual magnitude Apparent magnitude () is a measure of the brightness of a star, astronomical object or other celestial objects like artificial satellites. Its value depends on its intrinsic luminosity, its distance, and any extinction of the object's light ca ...
of 3.3, and is readily visible to the
naked eye Naked eye, also called bare eye or unaided eye, is the practice of engaging in visual perception unaided by a magnification, magnifying, Optical telescope#Light-gathering power, light-collecting optical instrument, such as a telescope or microsc ...
at night. The distance to this system is about based upon
parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different sightline, lines of sight and is measured by the angle or half-angle of inclination between those two lines. Due to perspective (graphica ...
measurements. It is drifting further away from the Sun with a
radial velocity The radial velocity or line-of-sight velocity of a target with respect to an observer is the rate of change of the vector displacement between the two points. It is formulated as the vector projection of the target-observer relative velocity ...
of +17 km/s.


Nomenclature

''δ Aquarii'' ( Latinised to ''Delta Aquarii'') is the star's
Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek alphabet, Greek or Latin letter followed by the genitive case, genitive form of its parent constellation's Latin name. The original list of Bayer design ...
. It also has the
Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the 88 modern constellations, modern constellations visible from southern England. They are named after John Flamsteed, au ...
76 Aquarii. It bore the traditional name ''Skat'' (also rendered ''Scheat'', ''Seat'', ''Sheat'', etc., which was erroneously applied to
Beta Pegasi Beta Pegasi (β Pegasi, abbreviated Beta Peg, β Peg), formally named Scheat , is a red giant star and the second-brightest star (after Epsilon Pegasi) in the constellation of Pegasus. It forms the upper right corner of the Great Squar ...
in late medieval times), from the
Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...
الساق ''al-sāq'' " shin". In 2016, the
International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...
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 ''Skat'' for this star on 21 August 2016, and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning ''
Palace Guard ''Palace Guard'' is an American crime drama television series that was briefly broadcast by CBS from October 18 to November 1, 1991, as part of its 1991 fall lineup. It was produced by Stephen J. Cannell. Synopsis ''Palace Guard'' is the story ...
'', refers to an asterism consisting of Delta Aquarii, 29 Aquarii, 35 Aquarii, 41 Aquarii, 47 Aquarii, 49 Aquarii,
Lambda Piscis Austrini Lambda Piscis Austrini, Latinized from λ Piscis Austrini, is a solitary star in the southern constellation of Piscis Austrinus. It has a blue-white hue and is visible to the naked eye with an apparent visual magnitude of +5.42 ...
,
HD 212448 HD may refer to: Business * H-D or Harley-Davidson, a motorcycle manufacturer * The Home Depot, NYSE stock symbol: HD Chemistry * Hydrogen deuteride, a diatomic compound of hydrogen and deuterium * Mustard gas Codes * Air Do, formerly Ho ...
,
Epsilon Piscis Austrini Epsilon Piscis Austrini, Latinized from ε Piscis Austrini, is a blue-white hued star in the southern constellation of Piscis Austrinus. It is visible to the naked eye with an apparent visual magnitude of +4.17. Based upon an annual ...
,
21 Piscis Austrini This is the list of notable stars in the constellation Piscis Austrinus, sorted by decreasing brightness. See also * List of stars by constellation References * * * * * {{Stars of Piscis Austrinus *List Piscis Austrinus Piscis Austrinus ...
,
20 Piscis Austrini This is the list of notable stars in the constellation Piscis Austrinus, sorted by decreasing brightness. See also * List of stars by constellation References * * * * * {{Stars of Piscis Austrinus *List Piscis Austrinus Piscis Austrinus ...
, Upsilon Aquarii, 68 Aquarii, 66 Aquarii, 61 Aquarii, 53 Aquarii, 50 Aquarii, 56 Aquarii, 45 Aquarii, 58 Aquarii, 64 Aquarii, 65 Aquarii, 70 Aquarii, 74 Aquarii, Tau2 Aquarii, Tau1 Aquarii, 77 Aquarii, 88 Aquarii, 89 Aquarii, 86 Aquarii, 101 Aquarii, 100 Aquarii, 99 Aquarii, 98 Aquarii, 97 Aquarii, 94 Aquarii, Psi3Aquarii, Psi2Aquarii, Psi1Aquarii, 87 Aquarii, 85 Aquarii, 83 Aquarii, Chi Aquarii, Omega1 Aquarii and Omega2 Aquarii. Consequently, the
Chinese name Chinese may refer to: * Something related to China * Chinese people, people identified with China, through nationality, citizenship, and/or ethnicity **Han Chinese, East Asian ethnic group native to China. **'' Zhonghua minzu'', the supra-ethni ...
for Delta Aquarii itself is (, ).AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日


Properties

The
spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...
of Delta Aquarii matches a
stellar classification In astronomy, stellar classification is the classification of stars based on their stellar spectrum, spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a Prism (optics), prism or diffraction gratin ...
of A3 Vp, indicating this is a chemically peculiar
A-type main-sequence star An A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...
that is generating energy through the
nuclear fusion Nuclear fusion is a nuclear reaction, reaction in which two or more atomic nuclei combine to form a larger nuclei, nuclei/neutrons, neutron by-products. The difference in mass between the reactants and products is manifested as either the rele ...
of hydrogen at its core. This star has three times the
Sun's mass The solar mass () is a frequently used unit of mass in astronomy, equal to approximately . It is approximately equal to the mass of the Sun. It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies a ...
and a radius 4.16 times as large. It is radiating 100 times the
luminosity of the Sun 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 nominal s ...
from its outer atmosphere 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 9,000 K. This heat gives it the characteristic white-hued glow of an A-type star. It has a relatively high rate of rotation, 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 bu ...
of 81 km s−1. Delta Aquarii does not display a strong signal of excess infrared emission that might indicate the presence of circumstellar matter. It is a probable stream star member of the
Ursa Major Moving Group The Ursa Major Moving Group, also known as Collinder 285 and the Ursa Major association, is the closest Stellar kinematics#Moving groups, stellar moving group – a set of stars with common velocities in space and thought to have a common orig ...
, which has an estimated age of 500 million years. An analysis of
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 and distances of ...
data strongly suggested a close companion object. An orbit was derived with a 483-day period, an eccentricity of 0.12, and an inclination of 41°. When Delta Aquarii was first examined for a companion, none was found. Any possible companion beyond was constrained to be less than .
Infrared Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...
interferometric Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...
observations did subsequently find a companion in 2017: a likely G5
main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...
star around from the primary.


References


External links


Star names derived from Arabic

Image Delta Aquarii
{{DEFAULTSORT:Delta Aquarii A-type main-sequence stars Ap stars Binary stars Ursa Major moving group Aquarius (constellation) Aquarii, Delta 8709 BD-16 6173 Aquarii, 076 216627 113136 Skat