Delta Draconis (δ Draconis, abbreviated Delta Dra, δ Dra), formally named Altais ,
is a yellow
star in the
constellation of
Draco
Draco is the Latin word for serpent or dragon.
Draco or Drako may also refer to:
People
* Draco (lawgiver) (from Greek: Δράκων; 7th century BC), the first lawgiver of ancient Athens, Greece, from whom the term ''draconian'' is derived
* ...
. It has 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 3.0,
[ making it easily visible to the naked eye. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 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 ...
.[
]
Nomenclature
''δ Draconis'' ( Latinised to ''Delta Draconis'') is the star's Bayer designation.
It bore the traditional names ''Aldib'', ''Altais''[ (the goat) and ''Nodus Secundus''.][ The title ''Altais'' was derived from ]Arabic
Arabic (, ' ; , ' or ) is a 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. E.Watson; Walter ...
''Al Tāis'' "the Goat", the association of this star, along with Pi Draconis, Rho Draconis and Epsilon Draconis (Tyl).[ According to a 1971 ]NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the US federal government responsible for the civil List of government space agencies, space program ...
catalog of stars, ''Al Tāis'' or ''Tais'' were the title for three stars : Delta Draconis as ''Altais'', Pi Draconis as ''Tais I'' and Rho Draconis as ''Tais II'' (exclude Epsilon Draconis).[ 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)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 '' Celestial Kitchen'' or ''Heaven's Kitchen'', refers to an asterism consisting of Delta Draconis, Sigma Draconis
Sigma Draconis is a single star in the northern constellation of Draco. It has the proper name Alsafi , while Sigma Draconis, which is latinised from σ Draconis and abbreviated Sig Dra or σ Dra, is the Bayer designation. It has an ap ...
, Epsilon Draconis, Rho Draconis, 64 Draconis and Pi Draconis. 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 ofte ...
for Delta Draconis itself is (, en, the First Star of Celestial Kitchen).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.
Properties
Delta Draconis is a giant star
A giant star is a star with substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moore, New York: Oxford University Press ...
with a stellar classification of G9 III. This indicates that, at an estimated age of 800 million years,[ it has exhausted the supply of hydrogen at its core and entered a later stage in its ]evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
. The angular diameter of the star is estimated as .[ At a parallax of 32.54 mas, this corresponds to a physical radius equal to 11 times the ]solar radius
Solar radius is a unit of distance used to express the size of stars in astronomy relative to the Sun. The solar radius is usually defined as the radius to the layer in the Sun's photosphere where the optical depth equals 2/3:
:1\,R_ = 6.957\ ...
.[ It is radiating 59][ times the luminosity of the Sun from its outer atmosphere at an effective temperature of 4,820 K.][ At this temperature, it is giving off the yellow-hued glow of a G-type star.][ With a mass 2.32][ times that of the Sun, this star will end its life as a ]white dwarf
A white dwarf is a stellar core remnant composed mostly of electron-degenerate matter. A white dwarf is very dense: its mass is comparable to the Sun's, while its volume is comparable to the Earth's. A white dwarf's faint luminosity comes ...
.[
]
Pole star
Delta Draconis is the northern pole star
A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body.
Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...
of Ceres
Ceres most commonly refers to:
* Ceres (dwarf planet), the largest asteroid
* Ceres (mythology), the Roman goddess of agriculture
Ceres may also refer to:
Places
Brazil
* Ceres, Goiás, Brazil
* Ceres Microregion, in north-central Goiás ...
, lying 1.5 degrees from the true pole.[Dawn explores Ceres: Results from the survey orbit]
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References
{{DEFAULTSORT:Delta Draconis
Draco (constellation)
Draconis, Delta
G-type giants
Altais
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Draconis, 57
180711
Durchmusterung objects
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