Gamma Sagittae, Latinized from γ Sagittae, is the brightest

star A star is an astronomical object comprising a luminous spheroid of plasma held together by its gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night, but their immense distances from Earth make ...

in northern constellation of

Sagitta Sagitta is a dim but distinctive constellation in the northern sky. Its name is Latin for 'arrow', not to be confused with the significantly larger constellation Sagittarius 'the archer'. It was included among the 48 constellations listed by t ...

. A single star, it is visible to the naked eye with 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 +3.47. Based upon an annual parallax shift of 12.62 mas as seen from Earth, it is located about 288

light-year 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 101 ...

s 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 rad ...

. It is moving closer to the Sun 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 rate of change of the distance or range between the two points. It is equivalent to the vector projection ...

of −34 km/s. This is a

red giant A red giant is a luminous giant star of low or intermediate mass (roughly 0.3–8 solar masses ()) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius large and the surface temperature around or ...

star with a

stellar classification In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting t ...

of M0 III. It is most likely (94% chance) on the

red-giant branch The red-giant branch (RGB), sometimes called the first giant branch, is the portion of the giant branch before helium ignition occurs in the course of stellar evolution. It is a stage that follows the main sequence for low- to intermediate-mass sta ...

of its

evolutionary 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 t ...

lifespan, fusing hydrogen along a shell to generate energy. The star is around 2.35 billion years old with roughly 55 times the Sun's radius. Mass estimates range from 0.9 to 1.8 times the

mass of the Sun The solar mass () is a standard unit of mass in astronomy, equal to approximately . It is often used to indicate the masses of other stars, as well as stellar clusters, nebulae, galaxies and black holes. It is approximately equal to the mass of ...

. It is radiating about 562 times the

Sun's luminosity 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 nomi ...

from its enlarged

photosphere The photosphere is a star's outer shell from which light is radiated. The term itself is derived from Ancient Greek roots, φῶς, φωτός/''phos, photos'' meaning "light" and σφαῖρα/''sphaira'' meaning "sphere", in reference to it ...

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 3,862 K.

Naming

In Chinese, (), meaning '' Left Flag'', refers to an asterism consisting of γ Sagittae,

α Sagittae Alpha Sagittae, formally named Sham , is a single star in the northern constellation of Sagitta. ''Alpha Sagittae'' is the Bayer designation, which is latinized from α Sagittae and abbreviated Alpha Sge or α Sge. It is visibl ...

β Sagittae Beta Sagittae, Latinized from β Sagittae, is a single star in the northern constellation of Sagitta. It is a faint star but visible to the naked eye with an apparent visual magnitude of 4.38. Based upon an annual parallax shift of 7.72 ...

δ Sagittae Delta Sagittae (Delta Sge, δ Sagittae, δ Sge) is a binary star in the constellation of Sagitta, with an apparent magnitude of +3.68. The primary component is a red M-type bright giant, and the secondary is a B-type main ...

ζ Sagittae Zeta Sagittae (ζ Sagittae) is triple star system in the northern constellation of Sagitta. It is visible to the naked eye, having a combined apparent visual magnitude of +5.00. Based upon an annual parallax shift of , the distance ...

, 13 Sagittae, 11 Sagittae, 14 Sagittae and ρ Aquilae. 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 oft ...

for γ Sagittae itself is (, en, the Fifth Star of Left Flag).AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 3 日
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References

External links

* {{DEFAULTSORT:Gamma Sagittae M-type giants Suspected variables Sagittae, Gamma Sagitta (constellation) Durchmusterung objects Sagittae, 12 189319 098337 7635