- Delta Crucis
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Delta Crucis Observation data
Epoch J2000 Equinox J2000Constellation Crux Right ascension 12h 15m 8.7s Declination −58° 44' 56" Apparent magnitude (V) 2.775 Characteristics Spectral type B2 IV U−B color index ? B−V color index ? Variable type Beta Cephei Astrometry Radial velocity (Rv) +22.2 km/s Proper motion (μ) RA: -36.68 mas/yr
Dec.: -10.72 mas/yrParallax (π) 8.96 ± 0.60 mas Distance 360 ± 20 ly
(112 ± 7 pc)Absolute magnitude (MV) -2.47 Details Mass 8.5 M☉ Radius 4.9 R☉ Luminosity 5,600 L☉ Temperature 22,500 K Metallicity ? Rotation < 1.3 days Age <30 millions years Other designations Delta Crucis (δ Cru, δ Crucis) is a B2IV star in the constellation Crux. It is sometimes called Pálida (Pale [one]) in Portuguese.[1]
It is of apparent magnitude 2.78 and about 360 light-years from Earth, the faintest of the four bright stars that form the constellation Crux. As a subgiant, it has left the stage of a B-dwarf star at the main sequence, is now developing into a red giant and will one day end as a white dwarf.
Delta Crucis is a Beta Cephei variable and changes its brightness subtly with a period of 1.3 hours. Its rotation is very fast, with a period of less than 1.3 days.
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Etymology
In Chinese, 十字架 (Shí Zì Jià), meaning Cross, refers to an asterism consisting of δ Crucis, γ Crucis, α Crucis and β Crucis.[2] Consequently, δ Crucis itself is known as 十字架四 (Shí Zì Jià sì, English: the Fourth Star of Cross.).[3]
The people of Aranda and Luritja tribe around Hermannsburg, Central Australia named Iritjinga, "The Eagle-hawk", a quadrangular arrangement comprising this star, γ Cru (Gacrux), γ Cen (Muhilfain) and δ Cen (Ma Wei).[4]
Modern legacy
δ Cru is represented in the flags of Australia, New Zealand and Papua New Guinea as one of five stars which comprise 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[5] .
References
- ^ da Silva Oliveira, R., "Crux Australis: o Cruzeiro do Sul", Artigos: Planetario Movel Inflavel AsterDomus.
- ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
- ^ (Chinese) AEEA (Activities of Exhibition and Education in Astronomy) 天文教育資訊網 2006 年 7 月 29 日
- ^ p. 8, Explorers of the southern sky: a history of Australian astronomy, Raymond Haynes, Cambridge, Cambridge University Press, 1996.
- ^ "Astronomy of the Brazilian Flag". FOTW Flags Of The World website. http://www.fotw.net/flags/br_astro.html.
External links
- "HD 106490 – Variable Star of beta Cep type". SIMBAD Astronomical Database. http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=delta+crucis&NbIdent=1&Radius=10&Radius.unit=arcmin&CooFrame=FK5&CooEpoch=2000&CooEqui=2000&output.max=all&o.catall=on&output.mesdisp=N&Bibyear1=1983&Bibyear2=2005&Frame1=FK5&Frame2=FK4&Frame3=G&Equi1=2000.0&Equi2=1950.0&Equi3=2000.0&Epoch1=2000.0&Epoch2=1950.0&Epoch3=2000.0. Retrieved 2005-11-05.
- DELTA CRU
Bayer - α (Acrux)
- β (Mimosa)
- γ (Gacrux)
- δ
- ε
- ζ
- η
- θ¹
- θ²
- ι
- κ
- λ
- μ
Categories:- Bayer objects
- Beta Cephei variables
- B-type subgiants
- Crux constellation
- Stars with proper names
- Variable star stubs
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