Lambda Boötis (λ Boötis, abbreviated Lam Boo, λ Boo), also named Xuange (), 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 northern

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 ...

Boötes Boötes ( ) is a constellation in the northern sky, located between 0° and +60° declination, and 13 and 16 hours of right ascension on the celestial sphere. The name comes from la, Boōtēs, which comes from grc-gre, Βοώτης, Boṓtēs ...

. 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, it is approximately 99

light-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s from the

Sun The Sun is the star at the center of the Solar System. It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core. The Sun radiates this energy mainly as light, ultraviolet, and infrared radi ...

. Lambda Boötis is a white A-type main sequence dwarf with an

apparent 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 li ...

of +4.18. It is the prototype of a group of rare stars known as

Lambda Boötis star A Lambda Boötis star is a type of chemically peculiar star which has an unusually low abundance of iron peak elements in its surface layers. One possible explanation for this is that it is the result of accretion of metal-poor gas from a circumste ...

s, all of which are dwarf stars with unusually low abundances of

metals A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

in their spectra. Its diameter has been directly measured to be 1.7 times that of the Sun.

Nomenclature

''λ Boötis'' ( Latinised to ''Lambda Boötis'') is the star's

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

. In

Chinese astronomy Astronomy in China has a long history stretching from the Shang dynasty, being refined over a period of more than 3,000 years. The ancient Chinese people have identified stars from 1300 BCE, as Chinese star names later categorized in the twe ...

, Lambda Boötis is called 玄戈,

Pinyin Hanyu Pinyin (), often shortened to just pinyin, is the official romanization system for Standard Mandarin Chinese in China, and to some extent, in Singapore and Malaysia. It is often used to teach Mandarin, normally written in Chinese for ...

: ''Xuángē'', meaning 'sombre lance', because this star is marking itself and standing alone in the ''Sombre Lance'' asterism,

Purple Forbidden enclosure The Purple Forbidden enclosure ( Zǐ wēi yuán) is one of the San Yuan ( Sān yuán) or Three Enclosures Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" ( Chi ...

(see :

Chinese constellations Traditional Chinese astronomy has a system of dividing the celestial sphere into asterisms or constellations, known as "officials" (Chinese ''xīng guān''). The Chinese asterisms are generally smaller than the constellations of Hellenistic t ...

). 玄戈 (''Xuángē'')

westernized Westernization (or Westernisation), also Europeanisation or occidentalization (from the ''Occident''), is a process whereby societies come under or adopt Western culture in areas such as industry, technology, science, education, politics, econo ...

into ''Heuen Ko'', but that name was assigned to

Gamma Boötis Gamma Boötis, Latinised from γ Boötis, is a binary star system in the northern constellation of Boötes the herdsman, forming the left shoulder of this asterism. The primary component has the proper name Seginus , the traditiona ...

by R.H. Allen, with the meaning of 'the heavenly spear'. In 2016, the IAU 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 approved the name ''Xuange'' for Lambda Boötis on 30 June 2017 and it is now so included in the List of IAU-approved Star Names. This star, along with the ''Aselli'' (

Theta Boötis Theta Boötis, Latinized from θ Boötis, is a star in the northern constellation of Boötes the herdsman, forming a corner of the upraised left hand of this asterism. It has the traditional name Asellus Primus (; Latin for "first donk ...

, Iota Boötis and Kappa Boötis), were ''Al Aulād al Dhiʼbah'' (ألعولد ألذعب - ''al aulād al dhiʼb''), "the Whelps of the Hyenas". ''Al Aulād al Dhiʼbah'' or ''Aulad al Thiba'' was the title of this star in a 1971

NASA The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding t ...

memorandum.Jack W. Rhoads - ''Technical Memorandum 33-507-A Reduced Star Catalog Containing 537 Named Stars'', Jet Propulsion Laboratory, California Institute of Technology; November 15, 1971
/ref>

References

External links

* * {{DEFAULTSORT:Lambda Bootis A-type main-sequence stars Lambda Boötis stars Bootis, Lambda Boötes Durchmusterung objects Bootis, 19 3837 125162 069732 5351