Delta Crucis
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Delta Crucis is a star in the southern constellation of Crux. It has the proper name Imai, pronounced Template:IPAc-en, which was adopted by the International Astronomical Union on 10 August 2018.[1] This is the faintest of the four bright stars that form the prominent asterism known as the Southern Cross. It is visible to the naked eye with an apparent visual magnitude of 2.8. Imai is a massive, hot and rapidly rotating star that is in the process of evolving into a giant. It is located at a distance of about Template:Convert from the Sun.
Nomenclature
δ Crucis (Latinised to Delta Crucis) is the star's Bayer designation. It is abbreviated Delta Cru or δ Cru.
The International Astronomical Union Working Group on Star Names (WGSN)[2] approved the name Imai for this star on 10 August 2018 and it is in the list of IAU-approved star names.[1] Imai is the name given to this star by the Mursi people of modern-day Ethiopia. The star Imai has some significance as when it "ceases to appear in the evening sky at dusk (around the end of August), it is said that the Omo River rises high enough to flatten the imai grass that grows along its banks, and then subsides."[3] The Mursi use a series of southern stars to mark their calendar to track seasonal flooding of the Omo River: Imai along with β Crucis (Thaadoi), β Centauri (Waar), and α Centauri (Sholbi).[4]
It is sometimes called Pálida (Pale [one]) in Portuguese.[5][6]
In Chinese, Template:Lang (Template:Lang), meaning Cross, refers to an asterism consisting of δ Crucis, γ Crucis, α Crucis and β Crucis.[7] Consequently, δ Crucis itself is known as Template:Lang (Template:Lang, Template:Langx).[8]
The Aranda and Luritja people around Hermannsburg, Central Australia named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, γ Cru (Gacrux), γ Cen (Muhlifain) and δ Cen (Ma Wei).[9]
Properties
This star has a stellar classification of B2 IV,[11] which suggests it is a subgiant star that is in the process of evolving away from the main sequence and becoming a red giant. Presently it is radiating around 8,100 times the luminosity of the Sun from its outer atmosphere at an effective temperature of 20,400 K,[12] causing it to glow with a blue-white hue.[13] Delta Crucis is a strong candidate Beta Cephei variable.[14] However, this is disputed.[15] Its rotation is very fast, with a projected rotational velocity of Template:Nowrap.[16]
Delta Crucis is a member of the Lower Centaurus Crux (LCC) component of the Scorpius–Centaurus association, which is an OB association of massive stars that share a common origin and motion through space.[17] This is the nearest OB association to the Sun, with the LCC component having an age in the range of 16–20 million years.[18] Template:Clear left
In culture
δ Cru is represented in the flags of Australia, New Zealand, Samoa and Papua New Guinea as one of the stars comprising the Southern Cross. It is also featured in the flag of Brazil, along with 26 other stars, each of which represents a state. δ Cru represents the state of Minas Gerais.[19]
Notes
References
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- ↑ Template:Cite web, Artigos: Planetario Movel Inflavel AsterDomus.
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- ↑ 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.
- ↑ Template:In lang AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日 Template:Webarchive
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