Iota Andromedae, also named Rasalnaqa, is a single

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 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 has the

Flamsteed designation A Flamsteed designation is a combination of a number and constellation name that uniquely identifies most naked eye stars in the 88 modern constellations, modern constellations visible from southern England. They are named after John Flamsteed, au ...

17 Andromedae, while ''Iota Andromedae'' is the

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 ...

as Latinized from ι Andromedae. This object is visible to the naked eye at night as a faint, blue-white hued star 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 +4.29. Based upon

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, it is located approximately 510

light years A light-year, alternatively spelled light year (ly or lyr), is a unit of length used to express astronomical distances and is equal to exactly , which is approximately 9.46 trillion km or 5.88 trillion mi. As defined by the International Astro ...

distant from the Sun. This object is a

B-type main-sequence star A B-type main-sequence star (B V) is a main-sequence (hydrogen-burning) star of spectral type B and luminosity class V. These stars have from 2 to 16 times the mass of the Sun and surface temperatures between 10,000 and 30,000 K. B-type stars ...

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 B8 V. It is among the least

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

s observed during the

Hipparcos ''Hipparcos'' was a scientific satellite of the European Space Agency (ESA), launched in 1989 and operated until 1993. It was the first space experiment devoted to precision astrometry, the accurate measurement of the positions and distances of ...

mission. The star is 116 million years old with 3.1 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 spinning 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 70 km/s. It is radiating 638 times the

luminosity of the Sun 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 ...

from its

photosphere The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will esc ...

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 12,620 K. The star is somewhat

metal-poor In astronomy, metallicity is the abundance of elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-dark) matter in the universe is either hydrogen or helium, and astronomers ...

, although the abundance of helium is close to solar. The latter excludes it from membership among the class of

peculiar star In astrophysics, chemically peculiar stars (CP stars) are stars with distinctly unusual metal abundances, at least in their surface layers. Classification Chemically peculiar stars are common among hot main-sequence (hydrogen-burning) stars. These ...

s. Iota Andromedae is a

debris disk A debris disk (American English), or debris disc ( Commonwealth English), is a circumstellar disk of dust and debris in orbit around a star. Sometimes these disks contain prominent rings, as seen in the image of Fomalhaut on the right. Debris ...

candidate, showing an

infrared excess An infrared excess is a measurement of an astronomical source, typically a star, that in their spectral energy distribution has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are of ...

at a

wavelength In physics and mathematics, wavelength or spatial period of a wave or periodic function is the distance over which the wave's shape repeats. In other words, it is the distance between consecutive corresponding points of the same ''phase (waves ...

of 18 μm.

Name

In the catalogue of stars in the ''Calendarium'' of

Al Achsasi al Mouakket Muḥammad al Achsasi al Mouakket () was a 17th century Egyptian astronomer whose and catalogue of stars, ("''Pearls of brilliance upon the solar operations''"), was written in Cairo in about 1650. Al-Achsasi was a shaykh, a learned elder, of th ...

, this star was designated ''Keff al-Salsalat'' (كف المسلسلة - ''kaf al-musalsala''), which was translated into

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

as ''Manus Catenata'', meaning ''hand of the chained woman'' (i.e. Andromeda). This name originally referred to a group of three starsι Andromedae,

κ Andromedae Kappa Andromedae, Latinized from κ Andromedae, also named Kaffalmusalsala, is a star in the northern constellation of Andromeda. It is visible to the naked eye with an apparent visual magnitude of 4.1. Based on the star's ranking on th ...

, 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 ...

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

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

References

{{DEFAULTSORT:Iota Andromedae B-type main-sequence stars Andromeda (constellation) Andromedae, Iota Andromedae, 17 BD+42 4720 116631 222173 8965 Rasalnaqa