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physical object > natural object > celestial body > star > early star > A star

A star
subject			fact

A star	has color white
	has surface temperature 10000 K
	has absorption line H I
	has definition Star with spectral type A in which the spectrum of the Balmer lines of hydrogen attain their greatest strength. Helium lines can no longer be seen. Some metallic lines are present; in late A stars the H and K lines of ionized calcium appear. A0 stars have a color index of zero.
	is a kind of early star
early star	has spectral type O, B, A, and early F
star	has star surface temperature
	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 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 A star :

• Ae star (4 facts) - A-type star with emission in one or several Balmer lines.
• Alpha Cephei (10 facts) (HR 8162)
• Alpha Circini (9 facts) (HR 5463)
• Alpha Coronae Autralis (10 facts) (HR 7254)
• Alpha Coronae Borealis (10 facts) (HR 5793)
• Alpha Doradus (10 facts) (HR 1465)
• Alpha Lacertae (10 facts) (HR 8585)
• Alpha Ophiuchi (10 facts) (HR 6556)
• Alpha Pictoris (10 facts) (HR 2550)
• Alpha Sextantis (10 facts) (HR 3981)
• Altair (14 facts) (alpha Aql, HR 7557) - A bright A7 V star.
• Am star (4 facts) - Peculiar star whose metallic lines are as strong as those of the F stars but whose hydrogen lines are so strong as to require that they be classed with the A stars. They are generally short-period (<300^d) spectroscopic binaries with high atmospheric turbulence and variable spectra, and are slower rotators than normal A stars., A-type or F-type object to which no unique spectral type can be assigned. Usually the classifier provides a classification according to the hydrogen, metallic and calcium lines. Also call metallic-line stars.
• Ap star (5 facts) - Stars can be classified according to their surface temperatures, which determine, in large part, the spectrum of radiation they emit. A stars have surface temperatures between about 7,500 and 11,000 degrees centigrade. Peculiar A stars are A stars whose emitted radiation spectra have many of the characteristics of A stars but are peculiar in certain ways., Star with spectral type A in which the lines of one or several elements are abnormally enhanced. Traditionally the most important subgroups are Si λ4200, Hg-Mn and Cr-Eu-Sr stars. The latest objects of the latter group correspond to early F-type., Peculiar A-type stars ("magnetic" A stars) that show abnormally strong lines, sometimes of varying intensity, of certain ionized metals. Recent evidence indicates that all Ap stars are slow rotators compared with normal A stars.
• Beta Trianguli (10 facts) (HR 622)
• Canum Venaticorum (9 facts) (HR 4915)
• Delta Capricorni (9 facts) (HR 8322)
• Epsilon Ursae Majoris (9 facts) (HR 4905)
• Fomalhaut (13 facts) (alpha PsA, HR 8728) - An A star. The brightest star in the constellation Piscis Austrinus.
• Magnetic star (2 facts) - Star (usually of spectral type A) with strong integrated magnetic fields ranging up to 30000 gauss.
• Sirius (16 facts) (alpha CMa, Dog Star, HR 2491) - The brightest star in the sky. Its companion (Sirius B) is a white dwarf of about 0.96 M_sun but only about 0.03 R_sun, the nearest white dwarf to Earth.
• Vega (13 facts) (alpha Lyr, HR 7001) - The fifth brightest star in the night sky.
• white giant (3 facts) - A giant star of spectral type A. Some RR Lyrae stars are white giants.
• white supergiant (2 kinds, 21 facts) - A supergiant star with a spectral type of A. White supergiants are rare; the nearest is Deneb, which lies 1500 light-years away.

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