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physical object > natural object > celestial body > collection of stars > star system > binary star > close binary > nova > dwarf nova

dwarf nova
subject			fact

dwarf nova	has definition A short-period binary system consisting of a hot white dwarf (or a hot blue sdBe subdwarf) and a much cooler and slightly more massive late-type main-sequence companion which fills its Roche lobe and is ejecting mass onto the white dwarf through its inner Lagrangian point. (The light from dwarf novae comes from four sources: a white dwarf, a cool main-sequence star, a hot spot, and a disk.) The outbursts are usually assumed to be caused by the explosive nuclear burning of hydrogen-rich material accreted onto the surface of a degenerate star.
	has definition Cataclysmic variable in which the brightness increases suddenly at intervals ranging from several days to years.
	is a kind of nova
nova	can become naked eye star
	has energy release 1044 ergs
	has use nova peak brightness distance determination
emission line star	has emission line
cataclysmic variable	has synonym eruptive variable
	has synonym explosive variable
	has peak brightness
	has recovery time
	has outburst start time
	has acronym CV
binary star	has number of stars 2
	has orbital period
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
star system	has abundance half the stars in the solar neighborhood are members of star systems
celestial body	has spectra
variable	has name designated with R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name RR, RS, RT, RU, RV, RW, RX, RY, or RZ and the genitive of the latin constellation name when the single letter designations are exhausted AA...AZ, BB...BZ, etc. (omitting J), which ends with QQ...QZ and the genitive of the latin constellation namewhen the RR...RZ designations are exhausted V 335, V 336, etc., when the double letter designations are exhausted
	has observational problem some difficulty in distinguishing between various kinds
	has observable variation time scale within a period of decades
	has light curve
	has optical brightness variation 0.2 magnitudes or greater
	has amplitude
physical object	has location or center of gravity
	has angular momentum
	has momentum
	has temperature
	has volume
	has extent

Kinds of dwarf nova :

• SS Cygni star (2 facts) - A subclass of dwarf nova. SS Cyg is a double-lined, noneclipsing spectroscopic binary (sdBe, dG5) with an orbital period of 6^h38^m. Mean time between eruptions, 54 days. It may be a sporadic source of soft X-rays.
• SU Ursa Major (2 facts)
• U Geminorum star (1 kind, 6 facts) - A type of dwarf nova. All U Geminorum stars are binaries containing a white dwarf and a red dwarf with total masses of roughly 1-2 M_sun and with periods of less than 12 hours (period of U Gem, 1.5 × 10⁴ seconds). About 150 are known.
• VW Hydri (2 facts)
• Z Camelopardalis star (1 kind, 9 facts) - A class of dwarf nova with standstills in their light curves. Z Cam itself is a semidetached binary (period 7^h21^m) consisting of a dG1 star and a hot white dwarf or a hot blue subdwarf which is probably degenerate. Mean time between eruptions, 20 days. Peak-to-peak amplitude, about 0.5 mag.

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