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

B star
subject			fact

B star	has color blue-white
	has surface temperature 11000 to 28000 K
	has absorption line He I
	has definition Blue-white star of spectral type B whose spectra are characterized by absorption lines of neutral helium which reach their maximum intensity at B2. The Balmer lines of hydrogen are strong, and lines of singly ionized oxygen and other gases are also present.
	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 B star :

• Achernar (13 facts) (alpha Eridani, HR 472)
• Alpha Andromedae (10 facts) (HR 15)
• Alpha Columbae (10 facts) (HR 1956)
• Alpha Gruis (10 facts) (HR 8425)
• Alpha Leonis (10 facts) (HR 3982)
• Alpha Lupi (10 facts) (HR 5469)
• Alpha Muscae (10 facts) (HR 4798)
• Alpha Pavonis (10 facts) (HR 7790)
• Alpha Pyxidis (10 facts) (HR 3468)
• Alpha Sculptoris (10 facts) (HR 280)
• Alpha Telescopii (10 facts) (HR 6897)
• Be star (1 kind, 9 facts) - Irregular variables of spectral type B (or occasionally O or A) with hydrogen emission lines in their spectra. The Be phenomenon involves rapid stellar rotation, circumstellar shells, and mass loss., Non-supergiant B-type stars, which have shown emission in at least one of the Balmer lines at some time.
• Bellatrix (6 facts) (gamma Orionis) - A B2 III star.
• Beta Crucis (10 facts) (HR 4853)
• Beta Librae (10 facts) (HR 5685)
• Bp star (3 kinds, 9 facts) - Peculiar B stars whose spectra show a deficiency in helium and 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.
• Bw star (2 facts) - B star with weak helium lines - i.e., B stars which, if classified according to their colors, would have helium lines too weak for the classification, and which, if classified according to their helium lines, would have colors too blue for their spectral type.
• Epsilon Sagittarii (10 facts) (HR 6879)
• Gamma Corvi (10 facts) (HR 4662)
• helium-strong star (2 facts) - B star in which the helium lines are stronger than in normal stars. One distinguishes usually the extreme helium stars (also called hydrogen-deficient stars), in which no trace of hydrogen is seen, and the intermediate helium-rich stars, in which the hydrogen lines are still visible, but weaker than in normal stars. Related to these objects are the hydrogen deficient C stars.
• P-strong star (2 facts) - A small subgroup of B-type stars in which P lines are very strong.
• Regulus (7 facts) (alpha Leo) - A visual triple B8 V star.
• Rigel (13 facts) (beta Ori, HR 1713) - A blue supergiant. It is a multiple star. The seventh brightest star in the night sky.
• sdB (3 facts) - Subdwarf B star with very broad and shallow Balmer lines; fewer lines of the Balmer series are visible than for normal dwarfs.
• Spica (17 facts) (alpha Vir, HR 5056) - A double-lined spectroscopic binary (B1.5 V, late B). Component A (10.9 M_sun) is a beta Cephei star which seems to be near core hydrogen exhaustion.
• Vela X-1 (11 facts) (HD 77581, 3U 0900-40)

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