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physical object > natural object > celestial body > star > Population II star

Population II star (halo star)
subject			fact

Population II star	is a part of halo
	has author Baade (1944)
	has synonym halo star
	has definition Older star with relatively low abundances of metals, usually found in the nucleus of a galaxy or in globular clusters. The Sun is a rather old Population I star.
	has definition Star that has high spatial velocity and low metallicity. This is not an observational definition.
	has definition Older observed stars formed mostly from hydrogen and helium.
	has definition Old stars typical of those found in the halo of the Galaxy.
	has definition Older stars, generally formed towards the centre of a galaxy, containing few heavier elements. The brightest of this Population are red giants.
	is a kind of star
star	has star surface temperature
	has spectral type
	has V magnitude
	has B magnitude
	has U magnitude
	has position on celestial sphere from the point of view of Earth
	has parallax from the point of view of Earth's orbit
	has proper motion
	has radiation at surface which is diffused out from the hotter core
	has energy source gravitational contraction and or fusion
	has energy production which takes place primarily within the core
	has surface density which depends on luminosity class
	has surface temperature greater than 1000 Kelvin
	has apparent magnitude
	has absolute magnitude
	has age
	has catalog star catalog
	has material hydrogen, helium
	has velocity determined from proper motion and radial velocity
	has mass greater than 0.08 the sun's mass
celestial body	has spectra
physical object	has location or center of gravity
	has angular momentum
	has momentum
	has temperature
	has volume
	has extent

Kinds of Population II star :

• blue halo star (2 facts) - Hot star in the horizontal-branch, post-horizontal-branch, and post-asymptotic branch phases of evolution.
• blue horizontal-branch star (4 facts) (HZ star) - Population II star (B3-A0) in the galactic halo, characterized by strong, sharp hydrogen lines and large Balmer jump, and very weak lines of all other elements., Blue horizontal-branch star, the first catalog of which was compiled by Humason and Zwicky.
• field horizontal branch star (3 facts) - High-velocity metal-weak star of either B or A spectral type.
• Population II Cepheid (7 facts) (W Virginis star) - A bright yellow star that pulsates like a Cepheid but is older and fainter.

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