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physical object > natural object > celestial body > star > dwarf

dwarf (d, main sequence star)
subject			fact

dwarf	has symbol d
	has luminosity class V
	has synonym main sequence star
	has definition Star, like the Sun, that fuses hydrogen into helium at its core. Ninety percent of all stars are main-sequence stars; examples are Sirius, Vega, Altair, and Alpha Centauri A, B, and C.
	has definition Star that is on the main sequence - that is, a star fusing hydrogen into helium at its core.
	has definition Star with mass equal to or less than that of the sun. More generally, any star on or below the main sequence in the Hertzprung-Russell diagram.
	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 dwarf :

• AE Aurigae (6 facts) - Runaway star which diverges from a comparatively small area in Orion.
• Alpha Caeli (10 facts) (HR 1502)
• alpha Centauri (16 facts) (Rigil Kent, HR 5459) - A binary star whose components have G2 V and K5 V spectral types. The nearest star system to the Sun and the third brightest star in the night sky.
• Alpha Cephei (10 facts) (HR 8162)
• Alpha Comae Berenices (9 facts) (HR 4969)
• Alpha Coronae Autralis (10 facts) (HR 7254)
• Alpha Coronae Borealis (10 facts) (HR 5793)
• Alpha Fornacis (10 facts) (HR 963)
• Alpha Lacertae (10 facts) (HR 8585)
• Alpha Leonis (10 facts) (HR 3982)
• Alpha Mensae (9 facts) (HR 2261)
• Altair (14 facts) (alpha Aql, HR 7557) - A bright A7 V star.
• Beta Librae (10 facts) (HR 5685)
• black dwarf (3 facts) - The final stage in the evolution of a star of roughly 1 M_sun. It is a mass of cold, electron-degenerate gas, and can no longer radiate energy, because the whole star is in its lowest energy state. No black dwarfs have ever been observed. Also, an object (M < 0.085 M_sun) that is not massive enough to achieve nuclear chain reactions.
• blue dwarf (2 facts) - High-temperature star (as opposed to red stars). Blue dwarfs represent the very dense, but very small, near-final form of what was once a red giant.
• brown dwarf (6 facts) - Star with too little mass to ignite its hydrogen 1 fuel. If brown dwarfs exist, they shine faint red for a time, as they convert gravitational energy into heat, and then fade and cool., A substellar object that is below the minimum mass required for nuclear fusion reactions to occur in its core., A self-gravitating, self-luminous gaseous object which is not sufficiently massive to result in thermonuclear hydrogen fusion reactions in its core and cannot therefore be considered a star. Such objects are expected to have a mass less than 7% of the Sun's mass and represent a "missing link" between low-mass stars and gas giant planets like Jupiter (at 0.1% of the Sun's mass).
• Epsilon Eri (7 facts) - In 1973 van de Kamp announced that this star has a planet-like object in orbit around it at a distance of about 8 AU and with a period of about 25 years.
• Epsilon Eridani (4 facts) - A young orange dwarf star that is visible to the naked eye.
• Epsilon Indi (3 facts) - An old orange dwarf star in the southern constellation Indus.
• Fomalhaut (13 facts) (alpha PsA, HR 8728) - An A star. The brightest star in the constellation Piscis Austrinus.
• Kruger 60 AB (7 facts) - A faint dM binary in the Solar neighborhood. It may be a subluminous star.
• red dwarf (5 kinds, 49 facts) - A main-sequence star with spectral type M. Red dwarfs are much fainter, cooler, and smaller than the Sun but are the most common type of star in the Galaxy, accounting for 70 percent of all stars.
• Regulus (7 facts) (alpha Leo) - A visual triple B8 V star.
• RW Aurigae (5 facts) - A T Tauri star with a strong ultraviolet excess.
• 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.
• Sun (37 facts) - Star that Earth orbits. Central body of solar system. It takes about 1-10 million years for photons to diffuse from the Sun's interior to its surface. About 3% of the energy radiated is in the form of neutrinos. Every second about 655 million tons of H are being converted into 650 million tons of He. A grazing light ray is deflected 1".7 by the Sun. If the total angular momentum of the solar system were concentrated in the Sun, its equatorial rotation speed would be about 100 km s^-1.
• Theta2 Orionis (8 facts) (2U 0525-06) - A spectroscopic binary tentatively identified with 2U 0525-06.
• UV Ceti star (3 kinds, 25 facts) - Late-type dwarfs with spectra showing hydrogen emission lines.
• Vega (13 facts) (alpha Lyr, HR 7001) - The fifth brightest star in the night sky.
• Zeta Ophiuchi (7 facts) - A reddened O star (a runaway star from the Sco-Cen association) with a high rotational velocity. It is well known for its strong interstellar absorption lines in the visible part of the spectrum.

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