Delta Leonis

Delta Leonis (δ Leonis, abbreviated Delta Leo, δ Leo), also named Zosma Template:IPAc-en,<ref name=Davis44>Template:Cite journal</ref><ref name="IAU-CSN">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> is a star in the zodiac constellation of Leo. Based upon parallax measurements, it lies at a distance of about Template:Convert from the Sun.<ref name=aaa474_2_653/>

Properties

δ Leonis is a main-sequence star with a stellar classification of A4 V,<ref name=aj74_375/> meaning it is larger and hotter than the Sun. It is a fairly well-studied star, allowing relatively accurate measurements of its age and size. The radius of the star, as measured directly using an interferometer, is about 214% of the Sun's radius and it is emitting more than 15 times as much luminosity as the Sun. The energy is being emitted from the outer envelope with an effective temperature Template:Val,<ref name=apj691_2_1896/> giving it the white hue characteristic of an A-type star. Having a larger mass than the Sun it will have a shorter lifespan, and in another 600 million years or so will swell into an orange or red giant star before decaying quietly into a remnant white dwarf consisting of carbon and oxygen.<ref name="kaler"/>

This star is rotating rapidly, with a projected rotational velocity of 180 km s⁻¹. The inclination of the axis of rotation to the line of sight from the Earth is estimated at 38.1°, which would mean the azimuthal velocity along the equator is about 280 km s⁻¹. This rotation is producing an equatorial bulge, giving the star a pronounced oblate spheroidal shape. The polar radius is about 84% of the radius along the equator.<ref name=aaa393_3_897/>

Based upon the location and trajectory of this star through space, it may be a member of the Ursa Major Moving Group, a type of stellar kinematics group that share a common origin and motion through space.<ref name=aj140_3_713/> The age of this group is about 500 million years.<ref name=aj125_4_1980/>

Nomenclature

δ Leonis (Latinised to Delta Leonis) is the star's Bayer designation.

It bore the traditional names Zosma or Zozma and Duhr (rare spellings included Zozca, Zosca, Al-Zubra الزبرة, traditional Arabic for both shoulder, and a lion's mane and Dhur ظهر, the latter meaning 'back' in ArabicTemplate:Citation needed). Zosma means 'girdle' in ancient Greek, referring to the star's location in its constellation, on the hip of the lion.<ref name=allen1899/> In 2016, the International Astronomical Union organized a Working Group on Star Names (WGSN)<ref name="WGSN">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> to catalog and standardize proper names for stars. The WGSN's first bulletin of July 2016<ref name="WGSN1">{{#invoke:citation/CS1|citation |CitationClass=web }}</ref> included a table of the first two batches of names approved by the WGSN, which included Zosma for this star.

In Chinese, {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}), meaning Right Wall of Supreme Palace Enclosure, refers to an asterism consisting of δ Leonis, β Virginis, σ Leonis, ι Leonis and θ Leonis.<ref>Template:In lang 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, Template:ISBN.</ref> Consequently, the Chinese name for δ Leonis itself is {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}, Template:Langx),<ref>Template:In lang 香港太空館 - 研究資源 - 亮星中英對照表 Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref> representing {{#invoke:Lang|lang}} ({{#invoke:Lang|lang}}), meaning The First Western Minister.<ref>Template:In lang English-Chinese Glossary of Chinese Star Regions, Asterisms and Star Name Template:Webarchive, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref> 西上相 (Xīshǎngxiāng), spelled Shang Seang by R.H. Allen,<ref name=allen1899/> means "the Higher Minister of State".<ref name=allen1899/>