Theta Leonis, Latinized from θ Leonis, formally named Chertan, is a

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

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 Leo. 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 +3.324 it is visible to the naked eye and forms one of the brighter stars in the constellation. The distance from the

Sun The Sun is the star at the centre of the Solar System. It is a massive, nearly perfect sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light a ...

can be directly determined from

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, yielding a value of about .

Description

This is a large star with 2.8 times the mass of the Sun and four times the Sun's radius. The

spectrum A spectrum (: spectra or spectrums) is a set of related ideas, objects, or properties whose features overlap such that they blend to form a continuum. The word ''spectrum'' was first used scientifically in optics to describe the rainbow of co ...

matches 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 A2 V, making this a seemingly typical

A-type main sequence star An A-type main-sequence star (A) or A dwarf star is a main-sequence (hydrogen burning) star of spectral type A and luminosity class (five). These stars have spectra defined by strong hydrogen Balmer absorption lines. They measure between 1.7 ...

. However, the spectrum shows enhanced absorption lines of metals, marking this as a chemically peculiar

Am star An Am star or metallic-line star is a type of chemically peculiar star of spectral type A whose spectrum has strong and often variable absorption lines of metals such as zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. ...

. The abundance of elements other than hydrogen and helium, what astronomers term the star's

metallicity In astronomy, metallicity is the Abundance of the chemical elements, abundance of Chemical element, elements present in an object that are heavier than hydrogen and helium. Most of the normal currently detectable (i.e. non-Dark matter, dark) matt ...

, appears around 12% higher than in the Sun. It is radiating 118 times the luminosity of the Sun from its outer atmosphere 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 9,480 K, literally giving it a white-hot glow. Theta Leonis is much younger than the Sun, with an estimated age of around 550 million years. It has a moderately high rate of rotation, 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 . However,

interferometric Interferometry is a technique which uses the '' interference'' of superimposed waves to extract information. Interferometry typically uses electromagnetic waves and is an important investigative technique in the fields of astronomy, fiber opt ...

observations suggest that it is a rapidly rotating star being viewed nearly pole-on. Measurements in the infrared band show an excess of emission from the star and its surroundings, suggesting the presence of a circumstellar disk of dust. The temperature of this emission indicates the disk has an orbital radius of 36 AU.

Nomenclature

''θ Leonis'' ( Latinised to ''Theta Leonis'') is the star's

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 ...

. It bore the traditional names ''Chertan'', ''Chort'' and ''Coxa'' . ''Chertan'' is derived from the

Arabic Arabic (, , or , ) is a Central Semitic languages, Central Semitic language of the Afroasiatic languages, Afroasiatic language family spoken primarily in the Arab world. The International Organization for Standardization (ISO) assigns lang ...

' 'two small ribs', originally referring to Delta Leonis and Theta Leonis; ''Chort'' from Arabic ' or ' 'small rib', and ' is

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 ...

for 'hip'. In 2016, the

International Astronomical Union The International Astronomical Union (IAU; , UAI) is an international non-governmental organization (INGO) with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreach, education, and developmen ...

organized a

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 approved by the WGSN; which included ''Chertan'' for this star. In Chinese, (), meaning '' Right Wall of Supreme Palace Enclosure'', refers to an asterism consisting of Theta Leonis,

Beta Virginis Beta Virginis, a name Latinised from β Virginis, is a star in the equatorial constellation of Virgo. It has the proper name Zavijava (), and, despite its designation 'beta', is the fifth-brightest star in Virgo with an apparent visual ...

, Sigma Leonis, Iota Leonis and Delta Leonis. 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 Theta Leonis itself is (, .), representing (), meaning ''The Second Western Minister''. 西次相 (Xīcìxiāng), spelled ''Tsze Seang'' by R.H. Allen, means "the Second Minister of State"

References

{{DEFAULTSORT:Theta Leonis Leo (constellation) Leonis, Theta Chertan A-type main-sequence stars Leonis, 70 054879 4359 097633 Durchmusterung objects