Delta Crucis

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Template:Short description

Template:Ubl
Template:Location mark
Location of δ Crucis (circled)
Observation data
Epoch J2000      Equinox J2000
Constellation Crux
Right ascension Template:RA[1]
Declination Template:DEC[1]
Apparent magnitude (V) 2.78 - 2.84[2]
Characteristics
Spectral type B2 IV[3]
U−B Template:Engvar −0.921[4]
B−V Template:Engvar −0.235[4]
Variable type β Cep[5]
Astrometry
Radial velocity (Rv)+22.2[6] km/s
Proper motion (μ) RA: −35.81[1] mas/yr
Dec.: −10.36[1] mas/yr
Parallax (π)9.45±0.15 mas[1]
DistanceTemplate:Rnd ± Template:Rnd ly
(Template:Rnd ± Template:Rnd pc)
Absolute magnitude (MV)−3.2[7]
Details
MassScript error: No such module "val".[8] Template:Solar mass
RadiusTemplate:Solar radius calculator[9]Template:Efn Template:Solar radius
LuminosityScript error: No such module "val".[9] Template:Solar luminosity
Surface gravity (log g)3.88[7] cgs
Temperature20,400[9] K
Rotational velocity (v sin i)210[10] km/s
AgeScript error: No such module "val".[8] Myr
Metallicity [Fe/H]{{{metal_fe2}}} dex
Other designations
Template:Odlist[11]
Database references
SIMBADdata

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Delta Crucis or δ Crucis, also identified as Imai (Template:IPAc-en), is a star in the southern constellation of Crux, and is the faintest of the four bright stars that form the prominent asterism known as the Southern Cross. This star has an apparent magnitude of 2.8, and its proper name was adopted by the International Astronomical Union on 10 August 2018.[12] Imai is a massive, hot and rapidly rotating star that is in the process of evolving into a giant, and is located at a distance of about Script error: No such module "convert". from the Sun.

Nomenclature

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

The International Astronomical Union Working Group on Star Names (WGSN)[13] approved the name Imai for this star on 10 August 2018 and it is in the list of IAU-approved star names.[12] Imai is the name selected for the star designated Delta Crucis 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." The Mursi use a series of southern stars to mark their calendar to track seasonal flooding of the Omo River.[14]

It is sometimes called Pálida (Pale [one]) in Portuguese.[15]

Properties

File:DeltaCruLightCurve.png
A light curve for Delta Crucis, plotted from TESS data[16]

This star has a stellar classification of B2 IV,[3] making it 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,[9] causing it to glow with a blue-white hue.[17] Delta Crucis is a strong candidate Beta Cephei variable.[5] Its rotation is very fast, with a projected rotational velocity of 210 km s−1.[10]

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.[7] 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]

In culture

In Chinese, Script error: No such module "Lang". (Script error: No such module "Lang".), meaning Cross, refers to an asterism consisting of δ Crucis, γ Crucis, α Crucis and β Crucis.[19] Consequently, δ Crucis itself is known as Script error: No such module "Lang". (Script error: No such module "Lang"., Template:Langx).[20]

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 (Muhilfain) and δ Cen (Ma Wei).[21]

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.[22]

Notes

Template:Notelist

References

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  1. ↑ a b c d e Script error: No such module "citation/CS1".
  2. ↑ Script error: No such module "Citation/CS1".
  3. ↑ a b Script error: No such module "citation/CS1".
  4. ↑ a b Script error: No such module "citation/CS1".
  5. ↑ a b Script error: No such module "citation/CS1".
  6. ↑ Script error: No such module "citation/CS1".
  7. ↑ a b c Script error: No such module "citation/CS1".
  8. ↑ a b Script error: No such module "citation/CS1".
  9. ↑ a b c d Script error: No such module "Citation/CS1".
  10. ↑ a b Script error: No such module "Citation/CS1".
  11. ↑ Script error: No such module "citation/CS1".
  12. ↑ a b Script error: No such module "citation/CS1".
  13. ↑ Script error: No such module "citation/CS1".
  14. ↑ Script error: No such module "citation/CS1".
  15. ↑ da Silva Oliveira, R., "Crux Australis: o Cruzeiro do Sul" Template:Webarchive, Artigos: Planetario Movel Inflavel AsterDomus.
  16. ↑ Script error: No such module "citation/CS1".
  17. ↑ Script error: No such module "citation/CS1".
  18. ↑ Script error: No such module "citation/CS1".
  19. ↑ 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.
  20. ↑ 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
  21. ↑ Script error: No such module "citation/CS1".
  22. ↑ Script error: No such module "citation/CS1".

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External links

Template:Stars of Crux Template:Authority control

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