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

eclipsing binary
subject			fact

eclipsing binary	has eclipse duration
	has definition A binary star of which, from the viewpoint of Earth, one of the two bodies regularly passes in front of the other. The resulting variation is perceived luminosity of some eclipsing binaries has led to their classification as variable stars.
	has definition A double star in which at least one of the two stars passes in front of and/or behind the other so that the system's total light periodically fades.
	has definition Eclipsing variables whose orbital plane lies so nearly in the line of sight that eclipses, as seen from the Earth, can occur and can be detected from their light curves.
	is a kind of periodic variable
	is a kind of close binary
periodic variable	has period
binary star	has number of stars 2
	has orbital period
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
star system	has abundance half the stars in the solar neighborhood are members of star systems
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 eclipsing binary :

• AS Eri (2 facts) - An eclipsing binary whose secondary is close to its Roche limit.
• beta Lyrae star (2 facts) - A class of eclipsing binary whose secondary minima are intermediate between those of Algol and those of W UMa. The prototype beta Lyr (B8.5 II, F V) is a complex eclipsing system and is presently in a state of rapid mass transfer. The spectrum of one companion is invisible; it may be a black hole. Beta Lyrae is also a weak radio source.
• beta Persei star (1 kind, 10 facts) - A class of eclipsing binary (see Algol) with periods of from 2 to 5 days, the depth of whose secondary minimum is almost negligible.
• BM Orionis (3 facts) - A peculiar eclipsing binary (B2-B3) in the Trapezium, with a flat-bottomed light curve suggesting a total eclipse. The spectrum of the secondary has never been seen.
• Centaurus X-3 (11 facts) (3U 1118-60, Krzeminski's star) - A pulsating binary X-ray source in the galactic plane. Optical component is Krzeminski's star, a B0 giant or supergiant. The X-ray component is probably a rotating neutron star of about 0.65-0.83 M_sun. Cen X-3 is speeding up at a rate of about 1 part in 10³-10⁵ per year and will at this rate fall into its companion in about 1000 years.
• CV Serpentis (5 facts) - A sometimes-eclipsing binary composed of a Wolf-Rayet star and a B0 star.
• DQ Herculis (8 facts) (Nova Herculis 1934) - A slow nova which also happens to be an eclipsing binary. It also has a regular flickering period of 71 seconds, the shortest period of regular variations known, except for pulsars and compact X-ray objects. It is probably composed of an M dwarf and a white dwarf with an accretion disk.
• epsilon Aurigae (7 facts) - An eclipsing binary with an invisible supergiant companion. The primary is an extremely luminous A8 Ia supergiant of 30 M_sun in a post-main-sequence stage of evolution; the secondary may be a collapsed star or black hole. It has at least six components.
• Hercules X-1 (9 facts) (3U 1653+35) - An X-ray pulsar, a member of an occulting binary system. The visible component has been identified as the blue variable HZ Herculis, whose spectrum varies from late A or early F to B. Her X- l has a pulsation period of 1.2378 seconds, presumably its rotation period, and exhibits a 35-day quasi-periodicity in the X-ray region (but not in the optical). It is probably a rotating neutron star in a circular orbit with a mass of about 0.7 M_sun, which is accreting matter from HZ Her. The orbital period is stable, but the pulsation period is speeding up at a rate of about 1 part in 10⁵ per year. The X-ray eclipse lasts 0.24 days.
• S Doradus (5 facts) - A supergiant eclipsing binary (an Eta Carinae-type object) in the Large Magellanic Cloud.
• Scorpius X-1 (7 facts) - A compact eclipsing X-ray source. It has day-to-day variations (period about 0.78 days?) of as much as 1 mag; it also has optical and radio counterparts but no correlation has been found among the flares observed at the three different wavelengths. It is a thermal X-ray source, probably associated with a rotating collapsed star surrounded by an extensive envelope. Tentative optical identification with the 13th mag blue variable V818 Sco. The spectrum of Sco X-1 is similar to that of an old nova. (3U 1617-15)
• Vela X-1 (11 facts) (HD 77581, 3U 0900-40)
• VV Cephei star (2 facts) - Eclipsing binaries with M supergiant primaries and blue (usually B) supergiant or giant secondaries. They have a rich emission spectrum. Sandage (1974) suggests M_v = - 7.3 for the M2p component of VV Cep.
• W Ursae Majoris star (2 facts) - A large class of double-lined eclipsing binaries with very short periods (a few hours) whose spectra indicate mass transfer. They are distinguished by the fact that their primary and secondary minima are equal. They are all F or G binaries on or near the main sequence. They may be the progenitors of dwarf novae.

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