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physical object > natural object > celestial body > collection of stars > star system > binary star > close binary > eclipsing binary > Hercules X-1
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Hercules X-1 comparison table
Subject is part of has acceptance statu has orbital period is an instance of has frequency has optical brightness variation has eccentricity has observational problem has distance has acronym has abundance has eclipse duration has wavelength is a kind of has name designated with has observable variation time scale has synonym has definition obey has number of star
eclipsing binary     0.2 magnitudes or greater some difficulty in distinguishing between various kinds  half the stars in the solar neighborhood are members of star systems  close binary
  1. R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name
  2. 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
  3. 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
  4. V 335, V 336, etc., when the double letter designations are exhausted
within a period of decades 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. 2
X-ray pulsardark halohypothetical  inversely proportional to the wavelength    PSR  inversely proportional to its momentumpulsar  hidden massPulsar (q.v.) that radiates in the X-ray region of the spectrum. Best verified examples are Her X-1 and Cen X-3. They are thought to be rotating, strongly magnetic neutron stars of about 1 Msun in a grazing orbit around a more massive star from which they are accreting matter.uncertainty principle 
Hercules X-1dark halohypothetical1.7 dayseclipsing binaryinversely proportional to the wavelength0.2 magnitudes or greatere < 0.1some difficulty in distinguishing between various kinds5 kpcPSRhalf the stars in the solar neighborhood are members of star systems0.24 days (in X-rays)inversely proportional to its momentum 
  1. R, S, T, U, V, W, X, Y, or Z and the genitive of the latin constellation name
  2. 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
  3. 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
  4. V 335, V 336, etc., when the double letter designations are exhausted
within a period of decades3U 1653+35An 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 Msun, 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.uncertainty principle2

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