104 Aquarii (abbreviated 104 Aqr) is a star in the

equatorial Equatorial may refer to something related to: *Earth's equator **the tropics, the Earth's equatorial region **tropical climate *the Celestial equator ** equatorial orbit **equatorial coordinate system ** equatorial mount, of telescopes * equatorial ...

constellation of

Aquarius Aquarius may refer to: Astrology * Aquarius (astrology), an astrological sign * Age of Aquarius, a time period in the cycle of astrological ages Astronomy * Aquarius (constellation) * Aquarius in Chinese astronomy Arts and entertainme ...

. ''104 Aquarii'' is the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the modern constellations visible from southern England. They are named for John Flamsteed who first used them while co ...

, although it also bears the Bayer designation A² Aquarii. Based on an annual parallax shift of only , the distance to this star is about . At that range, the brightness of the star in the V-band is reduced by 0.10 magnitudes as a result of

extinction Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...

caused by intervening gas and dust. This is a double star and possible

binary system A binary system is a system of two astronomical bodies which are close enough that their gravitational attraction causes them to orbit each other around a barycenter ''(also see animated examples)''. More restrictive definitions require that th ...

. The primary component has a stellar classification of G2 Ib/II, which places it on the borderline between the

bright giant 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 ...

and lower luminosity

supergiant Supergiants are among the most massive and most luminous stars. Supergiant stars occupy the top region of the Hertzsprung–Russell diagram with absolute visual magnitudes between about −3 and −8. The temperature range of supergiant stars spa ...

stars. It has passed the first

dredge-up A dredge-up is any one of several stages in the evolution of some stars. By definition, during a ''dredge-up'', a convection zone extends all the way from the star's surface down to the layers of material that have undergone fusion. Consequently, t ...

and may be undergoing Cepheid-like pulsations. With more than four times the mass of the Sun, this is an

evolved 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 ...

star that has reached its current stage after only 135 million years. It has expanded to around 51–88 times the Sun's radius and is radiating 447–fold the luminosity of the Sun. This energy is being emitted from its outer atmosphere at an effective temperature of 5,478 K, giving it the golden-hued glow of a

G-type star A G-type main-sequence star (Spectral type: G-V), also often, and imprecisely called a yellow dwarf, or G star, is a main-sequence star (luminosity class V) of spectral type G. Such a star has about 0.9 to 1.1 solar masses and an effective temp ...

. It is a suspected

variable star A variable star is a star whose brightness as seen from Earth (its apparent magnitude) changes with time. This variation may be caused by a change in emitted light or by something partly blocking the light, so variable stars are classified as e ...

. The companion is a magnitude 7.9 star with an angular separation of 120.1 arcseconds from the primary.

References

External links

Image 104 Aquarii
{{DEFAULTSORT:104 Aquarii Aquarius (constellation) Aquarii, A2 Aquarii, 104 Suspected variables Double stars G-type bright giants 116901 8982 222574 BD-18 6358