Theta Leonis, Latinized from θ Leonis, formally named Chertan, is a star in the constellation of Leo.
With an apparent visual magnitude 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 can be directly determined from parallax measurements, yielding a value of about .
Description
This is a large star with 2.5 times the mass of the Sun.
The spectrum matches a stellar classification of A2 V, making this a seemingly typical A-type main sequence star.
However, the spectrum shows enhanced absorption lines of metals, marking this as a chemically peculiar Am star.
The abundance of elements other than hydrogen and helium, what astronomers term the star's metallicity, appears around 12% higher than in the Sun.
It is radiating 141 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 9,350 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 of .
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.
It bore the traditional names Chertan, Chort  and Coxa .
Chertan is derived from the Arabic  'two small ribs', originally referring to Delta Leonis and Theta Leonis; Chort from Arabic  or  'small rib', and   is Latin for 'hip'.
In 2016, the International Astronomical Union organized a Working Group on Star Names (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, Sigma Leonis, Iota Leonis and Delta Leonis. 中國星座神話
, written by 陳久金.
Published by 台灣書房出版有限公司, 2005, .
Consequently, the Chinese name for Theta Leonis itself is  (, .), 香港太空館 - 研究資源 - 亮星中英對照表 , Hong Kong Space Museum.
Accessed on line November 23, 2010.
representing  (), meaning The Second Western Minister.
English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name , Hong Kong Space Museum.
Accessed on line November 23, 2010. 西次相 (Xīcìxiāng)
, spelled Tsze Seang by R.H. Allen, means "the Second Minister of State" References
