Kappa Scorpii, Latinized from κ Scorpii, is a

binary star A binary star is a system of two stars that are gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separate stars, in wh ...

system 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 ...

Scorpius Scorpius is a zodiac constellation located in the Southern celestial hemisphere, where it sits near the center of the Milky Way, between Libra to the west and Sagittarius to the east. Scorpius is an ancient constellation that pre-dates the Gre ...

. 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 2.4, this star system is readily visible to the naked eye.

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 place it at an estimated distance of roughly 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 ...

Properties

This is a

spectroscopic binary A binary star is a system of two star, stars that are gravity, gravitationally bound to and in orbit around each other. Binary stars in the night sky that are seen as a single object to the naked eye are often resolved using a telescope as separa ...

, which is a type of

system in which the two stars are so close together that they have not been individually resolved with a telescope. The pair orbit each other with a

period Period may refer to: Common uses * Era, a length or span of time * Full stop (or period), a punctuation mark Arts, entertainment, and media * Period (music), a concept in musical composition * Periodic sentence (or rhetorical period), a concept ...

of about 196 days and an

eccentricity Eccentricity or eccentric may refer to: * Eccentricity (behavior), odd behavior on the part of a person, as opposed to being "normal" Mathematics, science and technology Mathematics * Off-center, in geometry * Eccentricity (graph theory) of a v ...

of nearly 0.5. The combined

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...

of this pair matches a star 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 grati ...

of B1.5 III. The 'III'

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 ...

indicates the presence of a

giant star A giant star is a star with substantially larger radius and luminosity than a main sequence, main-sequence (or ''dwarf'') star of the same effective temperature, surface temperature.Giant star, entry in ''Astronomy Encyclopedia'', ed. Patrick Moo ...

that has exhausted the supply of hydrogen at its core and is in a late evolutionary stage. KappaScoLightCurve

The primary component of the pair, κ Sco A, is a

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 ...

Beta Cephei Beta Cephei (β Cephei, abbreviated Beta Cep, β Cep) is a triple star system of the third magnitude in the constellation of Cepheus. Based on parallax measurements obtained during the Hipparcos mission, it is approximately 690 light-ye ...

type. It is undergoing radial pulsations with a dominant frequency of 4.99922 cycles per day, or 4.8 hours per cycle. There are overlapping secondary pulsation frequencies of about 4.85 and 5.69 cycles per day. This star has about 17 times the mass of the Sun and is nearly 7 times the Sun's radius. The

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 the outer envelope is 23,400 K, giving it a blue-white hue. It is rotating rapidly, with an estimated period of only 1.9 days and an axis of rotation that is inclined by about 40° to the line of sight from the Earth. The secondary component, κ Sco B, is smaller than the primary, but still much larger than the Sun. It has about 12 times the mass of the Sun and nearly six times the Sun's radius. The

of 18,800 K is also higher than the Sun's, which is at 5,778 K.

Traditional name

κ Scorpii has been called Girtab , which is the Sumerian word for 'scorpion'. The name has survived through the

Babylonian star catalogues Babylonian astronomy collated earlier observations and divinations into sets of Babylonian star catalogues, during and after the Kassite rule over Babylonia. These star catalogues, written in cuneiform script, contained lists of constellations, i ...

, and was originally applied to an asterism comprising this star,

Lambda Scorpii Lambda Scorpii is a triple star system and the second-brightest object in the constellation of Scorpius. It is formally named Shaula; ''Lambda Scorpii'' is its Bayer designation, which is Latinised from λ Scorpii and abbreviated Lamb ...

Upsilon Scorpii Upsilon Scorpii (υ Scorpii, abbreviated Upsilon Sco, υ Sco), formally named Lesath , is a star located in the "stinger" of the southern zodiac constellation of Scorpius, the scorpion. Based on parallax measurements obtained during the H ...

, and

Iota Scorpii The Bayer designation ι Scorpii (Iota Scorpii) is shared by two stars in the constellation Scorpius (constellation), Scorpius: * Iota1 Scorpii, ι1 Scorpii * Iota2 Scorpii, ι2 Scorpii They are separated by 0.50° in the sky. Both of them were m ...

. In

Chinese Chinese can refer to: * Something related to China * Chinese people, people of Chinese nationality, citizenship, and/or ethnicity **''Zhonghua minzu'', the supra-ethnic concept of the Chinese nation ** List of ethnic groups in China, people of va ...

, (), meaning ''

Tail The tail is the section at the rear end of certain kinds of animals’ bodies; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, r ...

'', refers to an asterism consisting κ Scorpii, μ¹ Scorpii, ε Scorpii, ζ¹ Scorpii and ζ² Scorpii, η Scorpii, θ Scorpii, ι¹ Scorpii and ι² Scorpii, λ Scorpii and υ Scorpii. 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 often a ...

for κ Scorpii itself is (), "the Seventh Star of Tail".

Modern legacy

κ Scorpii appears on the

flag of Brazil The national flag of Brazil ( pt, bandeira do Brasil), is a blue disc depicting a starry sky (which includes the Southern Cross) spanned by a curved band inscribed with the national motto "''Ordem e Progresso''" ("Order and Progress"), within a y ...

, symbolising the state of

Paraíba Paraíba ( Tupi: ''pa'ra a'íba''; ) is a state of Brazil. It is located in the Brazilian Northeast, and it is bordered by Rio Grande do Norte to the north, Ceará to the west, Pernambuco to the south and the Atlantic Ocean to the east. Paraíba ...

References

External links

* {{Stars of Scorpius Scorpius (constellation) Scorpii, Kappa B-type giants Spectroscopic binaries Beta Cephei variables Girtab 086670 6580 160578 CD-38 12137