Iota Carinae (ι Carinae, abbreviated Iota Car, ι Car), officially named Aspidiske , is a

star A star is an astronomical object comprising a luminous spheroid of plasma (physics), plasma held together by its gravity. The List of nearest stars and brown dwarfs, nearest star to Earth is the Sun. Many other stars are visible to the naked ...

in the southern

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 origins of the e ...

Carina Carina may refer to: Places Australia * Carina, Queensland, a suburb in Brisbane * Carina Heights, Queensland, a suburb in Brisbane * Carina, Victoria, a locality in Mildura Serbia * Carina, Osečina, a village in the Kolubara District ...

. 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 2.2, it is one of the brighter stars in the night sky.

Appearance and location

The star and rest of southern Carina never sets on places from about 34° S southwards including

Cape Town Cape Town ( af, Kaapstad; , xh, iKapa) is one of South Africa's three capital cities, serving as the seat of the Parliament of South Africa. It is the legislative capital of the country, the oldest city in the country, and the second largest ...

; its northernmost viewpoints are unobstructed southern horizons near to the

30th parallel north The 30th parallel north is a circle of latitude that is 30 degree (angle), degrees true north, north of the Earth, Earth's equator, equatorial plane. It stands one-third of the way between the equator and the North Pole and crosses Africa, Asia, ...

, once a day. The

False Cross An asterism is an observed pattern or group of stars in the sky. Asterisms can be any identified pattern or group of stars, and therefore are a more general concept than the formally defined 88 constellations. Constellations are based on aster ...

is an asterism formed from Iota Carinae,

Delta Velorum Delta Velorum (δ Velorum, abbreviated Delta Vel, δ Vel) is a triple star system in the southern constellation of Vela, near the border with Carina, and is part of the False Cross. Based on parallax measurements, it is approxima ...

Kappa Velorum Kappa Velorum (κ Velorum, abbreviated Kappa Vel, κ Vel; proper name Markeb ) is a binary star system in the southern constellation of Vela. The two components are designated Kappa Velorum A and B. From parallax measurements, this syst ...

and

Epsilon Carinae Epsilon Carinae (ε Carinae, abbreviated Epsilon Car, ε Car), officially named Avior , is a binary star in the southern constellation of Carina. At apparent magnitude +1.86 it is one of the brightest stars in the night sky, but is not v ...

. It is so called because it is sometimes mistaken for the

Southern Cross Crux () is a constellation of the southern sky that is centred on four bright stars in a cross-shaped asterism commonly known as the Southern Cross. It lies on the southern end of the Milky Way's visible band. The name ''Crux'' is Latin for ...

, causing errors in

astronavigation Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space (or on the surface o ...

. The star appears 46.0' (0.7668°) WSW of lowercase a Carinae, a mid-third-magnitude star, also forming part of the asterism and leading to its long, narrow projection which culminates in

Canopus Canopus is the brightest star in the southern constellation of Carina and the second-brightest star in the night sky. It is also designated α Carinae, which is Latinised to Alpha Carinae. With a visual apparent magnitude ...

Nomenclature

''ι Carinae'' ( Latinised to ''Iota Carinae'') is the star's Bayer designation. It has the traditional cognate names ''Aspidiske'' (not be confused with ''Asmidiske'', the proper name of

Xi Puppis Xi Puppis (ξ Puppis, abbreviated Xi Pup, ξ Pup) is a multiple star system in the southern constellation of Puppis. With an apparent visual magnitude of 3.35, it is one of the brighter members of this constellation. ...

), ''Scutulum'' and ''Turais'' (or ''Tureis'', a name shared with

Rho Puppis Rho Puppis (ρ Puppis, abbreviated Rho Pup, ρ Pup), formally named Tureis , is a star in the southern constellation of Puppis. With an average apparent visual magnitude of 2.78, it is the third-brightest member o ...

). Turais is the

Arabic Arabic (, ' ; , ' or ) is a Semitic languages, Semitic language spoken primarily across the Arab world.Semitic languages: an international handbook / edited by Stefan Weninger; in collaboration with Geoffrey Khan, Michael P. Streck, Janet C ...

''تُرَيْس'' ''turais'' "small shield" (

diminutive A diminutive is a root word that has been modified to convey a slighter degree of its root meaning, either to convey the smallness of the object or quality named, or to convey a sense of intimacy or endearment. A (abbreviated ) is a word-formati ...

), while ''Aspidiske'' and ''Scutulum'' are

Greek Greek may refer to: Greece Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group. *Greek language, a branch of the Indo-European language family. **Proto-Greek language, the assumed last common ancestor ...

and

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

translations from ''ασπίδα'' and ''scūtum''. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

formed its

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 catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016 included a table of the first two batches of names it approved which included ''Aspidiske'' for this star. In

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, (), meaning '' Sea Rock'', refers to an asterism consisting of Iota Carinae,

, HD 83183, HD 84810 and Upsilon Carinae. Consequently, Iota Carinae itself is known as (, en, the Second Star of Sea Rock).

Properties

Based on

parallax Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...

measurements this star is about from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. It has 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 grati ...

of A9 Ib, with the

luminosity class 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 the ...

of 'Ib' indicating it has reached the stage of its

evolution 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 ...

where it has expanded to become a 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 ...

. Iota Carinae has more than seven times the

Sun's mass 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 ...

and has expanded to roughly 43 times the Sun's radius. It is radiating about 4,900 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 ...

. However, this luminosity appears to

vary Vary ( uk, Вари, hu, Vári or Mezővári) is a village in Zakarpattia Oblast (province) of western Ukraine. It is located around southeast of Berehove at the confluence of the rivers Tisza and Borzsova, not far from the Ukrainian- Hungar ...

, causing the star's apparent magnitude to range between 2.23–2.28. This energy is being radiated into space from the star's outer envelope 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 7,500 K, giving Iota Carinae the white hue typical of an

A-type star An A-type main-sequence star (A V) or A dwarf star is a main-sequence (hydrogen-burning) star of spectral type A and luminosity class V (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1 ...

. Due to

precession Precession is a change in the orientation of the rotational axis of a rotating body. In an appropriate reference frame it can be defined as a change in the first Euler angle, whereas the third Euler angle defines the rotation itself. In othe ...

of the Earth's

axis of rotation Rotation around a fixed axis is a special case of rotational motion. The fixed-axis hypothesis excludes the possibility of an axis changing its orientation and cannot describe such phenomena as wobbling or precession. According to Euler's rota ...

, in the next 7,500 years the south

celestial pole The north and south celestial poles are the two points in the sky where Earth's rotation around a fixed axis, axis of rotation, indefinitely extended, intersects the celestial sphere. The north and south celestial poles appear permanently dire ...

will pass close to this star and Upsilon Carinae and it will become the

South Star A pole star or polar star is a star, preferably bright, nearly aligned with the axis of a rotating astronomical body. Currently, Earth's pole stars are Polaris (Alpha Ursae Minoris), a bright magnitude-2 star aligned approximately with its ...

around 8100 CE.

References

{{DEFAULTSORT:Iota Carinae Carinae, Iota Carina (constellation) 080404 045556 Suspected variables A-type supergiants Aspidiske 3699 Durchmusterung objects