Xi 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
equatorial 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 name 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 ξ Aquarii, and abbreviated Xi Aqr or ξ Aqr. The system is 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 ...
as a point of light 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 4.7.
[ The two components are designated Xi Aquarii A (also named Bunda]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, this system lies at a distance of approximately from the Sun
The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...
.[ It is drifting closer with a heliocentric ]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 –26 km/s.[ The position of this system near the ]ecliptic
The ecliptic or ecliptic plane is the orbital plane of Earth's orbit, Earth around the Sun. It was a central concept in a number of ancient sciences, providing the framework for key measurements in astronomy, astrology and calendar-making.
Fr ...
means it is subject to lunar occultation.[
Xi Aquarii is a single-lined ]spectroscopic binary
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, which means that the presence of an unseen orbiting companion can be inferred from Doppler shift
The Doppler effect (also Doppler shift) is the change in the frequency of a wave in relation to an observer who is moving relative to the source of the wave. The ''Doppler effect'' is named after the physicist Christian Doppler, who described t ...
s in the spectral absorption line
Absorption spectroscopy is spectroscopy that involves techniques that measure the absorption (electromagnetic radiation), absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. Th ...
s. The two bodies orbit
In celestial mechanics, an orbit (also known as orbital revolution) is the curved trajectory of an object such as the trajectory of a planet around a star, or of a natural satellite around a planet, or of an artificial satellite around an ...
each other with a period of 8,016 days (22 y) and an eccentricity
Eccentricity or eccentric may refer to:
* Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal"
Mathematics, science and technology Mathematics
* Off-Centre (geometry), center, in geometry
* Eccentricity (g ...
of 0.54.[ The primary component, Xi Aquarii A, is an ]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 1.7 ...
with 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 A7 V.[ It has about 1.7][ times the ]mass of the Sun
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 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 bu ...
of 170 km/s.[ The star is radiating 36][ 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 photosphere
The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...
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 8,140 K.[
The orbital data is consistent with the secondary component, Xi Aquarii B, being either a ]red dwarf
A red dwarf is the smallest kind of star on the main sequence. Red dwarfs are by far the most common type of fusing star in the Milky Way, at least in the neighborhood of the Sun. However, due to their low luminosity, individual red dwarfs are ...
or a white dwarf
A white dwarf is a Compact star, stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very density, dense: in an Earth sized volume, it packs a mass that is comparable to the Sun. No nuclear fusion takes place i ...
star.[
]
Nomenclature
''ξ Aquarii'' ( Latinised to ''Xi Aquarii'') is the binary'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 ...
. The designations of the two components as ''Xi Aquarii A'' and ''B'' derive from the convention used by the Washington Multiplicity Catalog (WMC) for multiple star system
A star system or stellar system is a small number of stars that orbit each other, bound by gravitational attraction. It may sometimes be used to refer to a single star. A large group of stars bound by gravitation is generally called a ''st ...
s, and adopted by 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 ...
(IAU).Beta Aquarii
Beta Aquarii is a single yellow supergiant star in the constellation of Aquarius. It has the official name Sadalsuud () and the Bayer designation β Aquarii, abbreviated Beta Aqr or β Aqr. Based upon parallax measurements obtained duri ...
(Sadalsuud) it constituted the Persian lunar mansion
Often called lunar mansion, a lunar station or lunar house is a segment of the ecliptic through which the Moon passes in orbit of the Moon, its orbit around the Earth. The concept was used by several ancient cultures as part of their calendrical ...
''Bunda''.[ In 2016, the IAU 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)Al Achsasi al Mouakket
Muḥammad al Achsasi al Mouakket () was a 17th century Egyptian astronomer whose and catalogue of stars, ("''Pearls of brilliance upon the solar operations''"), was written in Cairo in about 1650. Al-Achsasi was a shaykh, a learned elder, of th ...
, this star was designated ''Thanih Saad al Saaoud'' ( – ), which was translated into Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
as , meaning "the second of luck of lucks".[ This star, along with Beta Aquarii and 46 Capricorni, were (), "the Luck of Lucks".][
In Chinese, (), meaning '' Celestial Ramparts'', refers to an asterism consisting of Xi Aquarii, 46 Capricorni, 47 Capricorni, Lambda Capricorni, 50 Capricorni, 18 Aquarii, 29 Capricorni, 9 Aquarii, 8 Aquarii, Nu Aquarii, 14 Aquarii, 17 Aquarii and 19 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 Xi Aquarii itself is (, ).香港太空館 - 研究資源 - 亮星中英對照表
, Hong Kong Space Museum. Accessed on line November 23, 2010.
References
External links
Image ξ Aqr
{{DEFAULTSORT:Xi Aquarii
A-type main-sequence stars
Spectroscopic binaries
Aquarius (constellation)
Aquarii, Xi
8264
BD-08 5701
Aquarii, 023
205767
106786
Bunda