Delta Draconis (δ Draconis, abbreviated Delta Dra, δ Dra), formally named Altais , is a yellow

star A star is a luminous spheroid of plasma (physics), plasma held together by Self-gravitation, self-gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night sk ...

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 Draco. It has 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 3.0, making it easily visible to the naked eye. Based on

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 obtained by the

Gaia In Greek mythology, Gaia (; , a poetic form of ('), meaning 'land' or 'earth'),, , . also spelled Gaea (), is the personification of Earth. Gaia is the ancestral mother—sometimes parthenogenic—of all life. She is the mother of Uranus (S ...

mission, it is 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 ...

Nomenclature

''δ Draconis'' ( Latinised to ''Delta Draconis'') 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 bore the traditional names ''Aldib'', ''Altais'' (the goat) and ''Nodus Secundus''. The title ''Altais'' was derived from

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 ...

''Al Tāis'' "the Goat", the association of this star, along with Pi Draconis, Rho Draconis and

Epsilon Draconis Epsilon Draconis, Latinized from ε Draconis, is a binary star in the constellation Draco, with a combined apparent magnitude of 3.84, it is the eleventh-brightest star in this rather faint constellation. This star along with Delta D ...

(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 federal government of the United States, US federal government responsible for the United States ...

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; , 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 ''Altais'' for this star on 21 August 2016 and it is now so included in the List of IAU-approved Star Names. In Chinese, (), meaning '' Celestial Kitchen'' or ''Heaven's Kitchen'', refers to an asterism consisting of Delta Draconis, Sigma Draconis, Epsilon Draconis, Rho Draconis, 64 Draconis and Pi Draconis. 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 Draconis 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.

Properties

Delta Draconis is a

giant star A giant star has a substantially larger radius and luminosity than a main-sequence (or ''dwarf'') star of the same surface temperature. They lie above the main sequence (luminosity class V in the Yerkes spectral classification) on the Hertzsp ...

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 G9 III. This indicates that it has exhausted the supply of hydrogen at its core and entered a later stage in its

evolution Evolution is the change in the heritable Phenotypic trait, characteristics of biological populations over successive generations. It occurs when evolutionary processes such as natural selection and genetic drift act on genetic variation, re ...

. Around 1.7 billion years old, Delta Draconis has expanded to 10.5 times the

Sun's radius Solar radius is a unit of distance used to express the size of objects 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\ti ...

and is radiating 59 times the luminosity of the Sun 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 4,873 K. At this temperature, it is giving off the yellow-hued glow of a G-type star. With a mass 1.7 times that of the Sun, this star will end its life as 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 ...

Pole star

Delta Draconis is the northern

pole star A pole star is a visible star that is approximately aligned with the axis of rotation of an astronomical body; that is, a star whose apparent position is close to one of the celestial poles. On Earth, a pole star would lie directly overhead when ...

of Ceres, lying 1.5 degrees from the true pole.

References

{{DEFAULTSORT:Delta Draconis Draco (constellation) Draconis, Delta G-type giants Altais 094376 Draconis, 57 180711 Durchmusterung objects 7310