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'''Acrux''' ([[alpha (letter)|α]] Crucis) is a [[star]] in the [[constellation]] [[Crux]], the Southern Cross. Since the Southern Cross is roughly 60 degrees below the [[celestial equator]], Crux is only visible south of the [[Tropic of Cancer]] and therefore didn't receive an ancient proper name; "Acrux" is simply a combination of the A in Alpha plus Crux. Acrux has a [[stellar magnitude]] of 0.77, and is the twelfth brightest star in the sky. It is the southernmost first magnitude star, just beating out [[Rigil Kentaurus]] (α Centauri).
::~ [[Kailua, Hawaii]] is located on the Island of [[Oahu|O'ahu]].
Acrux is a [[trinary star]] located 320 light years from the solar system. Only two components are visually distinguishable, α<sup>1</sup> and α<sup>2</sup>, separated by 4 [[arcsecond]]s. α<sup>1</sup> is magnitude 1.33 and α<sup>2</sup> is magnitude 1.73, both hot [[stellar classification|class B]] (almost [[stellar classification|class O]]) stars, with surface temperatures of about 28,000 and 26,000 Kelvin respectively; their respective luminosities are 2,500 and 1,600 times that of the Sun. α<sup>1</sup> and α<sup>2</sup> orbit over such a long period that motion is only barely seen. From their minimum separation of 430 [[astronomical unit]]s, the period is at least 1500 years, and may be much longer.
'''Kailua-Kona''' is a town located in [[Hawaii County, Hawaii]], in the North Kona District of the Island of [[Hawaii|Hawai'i]].
α<sup>1</sup> is itself a [[spectroscopic binary]] star, with its components thought to be around 14 and 10 times the mass of the Sun and orbiting in only 76 days at a separation of about one astronomical unit. The masses of α<sup>2</sup> and the brighter component of α<sup>1</sup> suggest that the stars will someday explode as [[supernova|supernovae]]. The fainter component of α<sup>1</sup> may survive to become a massive [[white dwarf]].
As of the [[2000 Census]], the town had a total population of 9,870. Although the correct name is just "Kailua", this town is known as Kailua-Kona to differentiate it from the much larger, [[Kailua, Hawaii|Kailua]] on windward [[Oahu|O'ahu]]. Many place names in the Hawaiian Islands are repeated on several islands, but the two Kailua's are the only confusing conflict in this regard.
Another class B subgiant lies 90 arcseconds away from triple Acrux and shares Acrux's motion through space, suggesting it may be gravitationally bound to Acrux. However, if it is indeed located near Acrux, it is under-luminous for its class. It is probably just an optical [[double star]], most likely lying over twice as far away from the solar system as Acrux.
The city is served by [[Kona International Airport]].
[[Category:Stars]]
== Geography ==
[[de:Acrux]]
Kailua is located at 19°38'60" North, 155°59'39" West (19.649973, -155.994028)[[Geographic references|<sup>1</sup>]].
[[ja:アクルックス]]
According to the [[United States Census Bureau]], the town has a total area of 103.0 [[square kilometer|km²]] (39.8 [[square mile|mi²]]). 91.9 km² (35.5 mi²) of it is land and 11.0 km² (4.3 mi²) of it is water. The total area is 10.71% water.
== Demographics ==
As of the [[census]] of [[2000]], there are 9,870 people, 3,537 households, and 2,429 families residing in the town. The [[population density]] is 107.3/km² (278.0/mi²). There are 4,322 housing units at an average density of 47.0/km² (121.7/mi²). The racial makeup of the town is 38.65% White, 0.46% [[African American]], 0.46% [[Native American]], 18.28% [[Asia|Asian]], 13.16% Pacific Islander, 1.93% from other races, and 27.07% from two or more races. 10.20% of the population are [[Hispanic]] or [[Latino]] of any race.
There are 3,537 households out of which 35.0% have children under the age of 18 living with them, 49.6% are married couples living together, 13.6% have a female householder with no husband present, and 31.3% are non-families. 22.6% of all households are made up of individuals and 7.2% have someone living alone who is 65 years of age or older. The average household size is 2.78 and the average family size is 3.26.
In the town the population is spread out with 27.3% under the age of 18, 9.0% from 18 to 24, 28.8% from 25 to 44, 24.9% from 45 to 64, and 10.0% who are 65 years of age or older. The median age is 36 years. For every 100 females there are 98.8 males. For every 100 females age 18 and over, there are 95.8 males.
The median income for a household in the town is $40,874, and the median income for a family is $46,657. Males have a median income of $30,353 versus $26,471 for females. The per capita income for the town is $20,624. 10.8% of the population and 6.5% of families are below the poverty line. Out of the total people living in poverty, 11.9% are under the age of 18 and 3.9% are 65 or older.
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