Kappa Andromedae, Latinized from κ Andromedae, also named Kaffalmusalsala, is a star in the northern

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 Andromeda. It is visible to the naked eye 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 4.1. Based on the star's ranking on the

Bortle Dark-Sky Scale The Bortle dark-sky scale (usually referred to as simply the Bortle scale) is a nine-level numeric scale that measures the night sky's sky brightness, brightness of a particular location. It quantifies the astronomy, astronomical observability of ...

, it is luminous enough to be visible from the suburbs and from urban outskirts, but not from brightly lit inner city regions.

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 place it at a distance of approximately . It is drifting closer with a

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 −13 km/s, and there is a high likelihood (86%) that it is a member of the

Beta Pictoris moving group The Beta Pictoris moving group is a young moving group of stars located relatively near Earth. A moving group, in astronomy, is a group of stars that share a common motion through space as well as a common origin. This moving group is named for Be ...

. The star has one known

exoplanet An exoplanet or extrasolar planet is a planet outside the Solar System. The first confirmed detection of an exoplanet was in 1992 around a pulsar, and the first detection around a main-sequence star was in 1995. A different planet, first det ...

Kappa Andromedae b Kappa Andromedae b is a directly imaged substellar object and likely superjovian-mass planet orbiting Kappa Andromedae, a young B9IV star in the Andromeda (constellation), Andromeda constellation, about 170 light-years away. The companion's mass ...

Naming

In traditional Arabic astronomy, the stars ι Andromedae, κ Andromedae, and

λ Andromedae Lambda Andromedae, Latinized from λ Andromedae, also named Udkadua, is a binary star system in the northern constellation of Andromeda. At an estimated distance of approximately from Earth, it has an apparent visual magnitude of arou ...

were known as ''Kaff al-Musalsala'', the hand of the chained woman (i.e. Andromeda), and as ''Ra’s al-Nāqa'', the head of the she-camel. The

IAU 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 ...

approved the name Kaffalmusalsala for κ Andromedae on 8 May 2025 and it is now so entered in the IAU Catalog of Star Names; the name Rasalnaqa was given to ι Andromedae. In

Chinese 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-ethnic ...

, (), meaning '' Flying Serpent'', refers to an asterism consisting of κ Andromedae, α Lacertae,

4 Lacertae 4 Lacertae is a single blue supergiant star in the northern constellation Lacerta, located about 2,600 light years away. This object visible to the naked eye as a white-hued star with an apparent visual magnitude of 4.55. It is moving ...

, π² Cygni, π¹ Cygni,

HD 206267 HD 206267A is a hierarchical triple star system in the northern circumpolar constellation of Cepheus. Two of the members form a spectroscopic binary that orbit each other with a period of 3.7 days, while a third member lies further awa ...

ε Cephei Epsilon Cephei, Latinized from ε Cephei, is a star in the northern constellation of Cepheus. Based upon an annual parallax shift of 38.17 mas as seen from the Earth, it is located about 85 light years from the Sun. The star ...

, β Lacertae, σ Cassiopeiae, ρ Cassiopeiae, τ Cassiopeiae,

AR Cassiopeiae AR Cassiopeiae (AR Cas) is a variable star in the constellation of Cassiopeia (constellation), Cassiopeia. It is thought to be a member of a multiple star system, septuple star system, one of only two known star systems with a multipl ...

9 Lacertae 9 Lacertae is a single star in the northern constellation Lacerta, located 172 light years away from Sun. It is visible to the naked eye as a faint, white-hued star with an apparent visual magnitude of 4.64. This object is moving furt ...

3 Andromedae 3 Andromedae, abbreviated 3 And, is a single star in the northern constellation of Andromeda. ''3 Andromedae'' is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 4.64. The distance to this ...

7 Andromedae 7 Andromedae, also named Honores, is a single, yellow-white hued star in the northern constellation of Andromeda. ''7 Andromedae'' is the Flamsteed designation, abbreviated 7 And. It is visible to the naked eye with an apparent visual m ...

8 Andromedae 8 Andromedae, abbreviated 8 And, is a probable triple star system in the northern constellation of Andromeda. ''8 Andromedae'' is the Flamsteed designation. It is visible to the naked eye with an apparent visual magnitude of 4.82. Base ...

, ι Andromedae, and

ψ Andromedae Psi Andromedae (ψ And, ψ Andromedae) is the Bayer designation for a triple star system in the northern constellation of Andromeda. The combined apparent visual magnitude of this system is 4.95. Based upon parallax measurements, is roug ...

. 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 κ Andromedae itself is (, ).AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 7 日

Properties

The

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 Kappa Andromedae is B9 IVn, indicating that it is a

subgiant star A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution of ...

in the process of

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

away from the

main sequence In astronomy, the main sequence is a classification of stars which appear on plots of stellar color index, color versus absolute magnitude, brightness as a continuous and distinctive band. Stars on this band are known as main-sequence stars or d ...

. The star has an estimated 2.8 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 radiating 78.5 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 nominal s ...

. It 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 162 km/s. Its true rotational velocity is 283.8 km/s, which is about 85% of its critical rotation rate (the rate at which it would break up). With such a rapid rotation rate, the star is deformed into an oblate spheroid, such that while the polar radius is , the equatorial radius is significantly larger, at . The outer envelope of the star is radiating energy into space with 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 10,342 K at the equator and 12,050 K at its poles, producing a blue-white hue. The age of Kappa Andromedae has been the subject of debate. The discovery paper for Kappa Andromedae b argued that the primary's kinematics are consistent with membership in the Columba Association, which would imply a system age of 20-50 million years, while a subsequent work derived an older age of 220±100 million years based on the star's position on the Hertzsprung-Russell diagram position assuming that the star is not a fast rotator viewed pole-on. Direct measurements of the star later showed that Kappa Andromedae A is in fact a rapid rotator viewed nearly pole-on and yield a best-estimated age of 47 million years.

Planetary system

In November 2012, members of the Strategic Explorations of Exoplanets and Disks with Subaru (SEEDS) survey reported the discovery of a faint, directly-imaged companion

. Follow-up photometry and spectroscopy of kappa And b with the

Subaru Telescope is the telescope of the National Astronomical Observatory of Japan, located at the Mauna Kea Observatory on Hawaii. It is named after the open star cluster known in English as the Pleiades. It had the largest monolithic primary mirror in the ...

Keck Observatory The W. M. Keck Observatory is an astronomical observatory with two telescopes at an elevation of 4,145 meters (13,600 ft) near the summit of Mauna Kea in the U.S. state of Hawaii. Both telescopes have aperture primary mirrors, and, when c ...

, and

Large Binocular Telescope The Large Binocular Telescope (LBT) is an optical telescope for astronomy located on Mount Graham, in the Pinaleno Mountains of southeastern Arizona, United States. It is a part of the Mount Graham International Observatory. When using both ...

constrained its mass to be about 13 Jupiter masses, temperature to be between 1700 K and 2150 K, and orbit to be highly eccentric with a semimajor axis likely greater than about 75 AU. The companion's spectrum shows evidence for water and carbon monoxide molecules and suggests the object has a low surface gravity.

References

External links

Image κ Andromedae
{{DEFAULTSORT:Kappa Andromedae B-type subgiants Planetary systems with one confirmed planet Andromeda (constellation) Andromedae, Kappa 8976 BD+43 4522 Andromedae, 19 222439 116805 Kaffalmusalsala

Naming

Properties

Planetary system

See also

References

External links