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Crab Pulsar
Chandra-crab.jpg
The Crab Nebula, which contains the Crab Pulsar. Image combines optical data from Hubble (in red) and X-ray images from Chandra (in blue). NASA/CXC/ASU/J. Hester et al.[1]
Observation data
Epoch J2000      Equinox J2000
Constellation Taurus
Right ascension 05h 34m 31.97s
Declination +22° 00' 52.1"'
Apparent magnitude (V) 16.5
Characteristics
Spectral type F
U-B color index -0.45
B-V color index +0.5
Variable type None
Astrometry
Proper motion (μ) RA: -14.7±0.8[2] mas/yr
Dec.: 2.0±0.8[2] mas/yr
Distance 2000[2] pc
Details
Mass ? M
Radius ? R
Luminosity ? L
Temperature ? K
Rotation 29.6 second-1[2]
Age 954 (as of 2008) years
Other designations
SNR G184.6-05.8, 2C 481, 3C 144.0, SN 1054A, 4C 21.19, NGC 1952, PKS 0531+219, PSR B0531+21, PSR J0534+2200, CM Tau.
Database references
SIMBAD pulsar data
A slow-motion movie of the Crab Pulsar taken at 800 nm wavelength using a Lucky Imaging camera from Cambridge University, showing the bright pulse and fainter interpulse.

The Crab Pulsar (PSR B0531+21) is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054.[3][4][5] Discovered in 1968, the pulsar was the first to be connected with a supernova remnant.[6]

The optical pulsar is roughly 25 km in diameter and the pulsar "beams" rotate once every 33 milliseconds, or 30 times each second. The outflowing relativistic wind from the neutron star generates synchrotron emission, which produces the bulk of the emission from the nebula, seen from radio waves through to gamma rays. The most dynamic feature in the inner part of the nebula is the point where the pulsar's equatorial wind slams into the surrounding nebula, forming a termination shock. The shape and position of this feature shifts rapidly, with the equatorial wind appearing as a series of wisp-like features that steepen, brighten, then fade as they move away from the pulsar into the main body of the nebula. The period of the pulsar's rotation is slowing by 38 nanoseconds per day due to the large amounts of energy carried away in the pulsar wind.[7]

The Crab Nebula is often used as a calibration source in X-ray astronomy. It is very bright in X-rays and the flux density and spectrum are known to be constant, with the exception of the pulsar itself. The pulsar provides a strong periodic signal that is used to check the timing of the X-ray detectors. In X-ray astronomy, 'crab' and 'millicrab' are sometimes used as units of flux density. A millicrab corresponds to a flux density of about 2.4x10-11 erg s-1 cm−2 (2.4x10-14 W m−2) in the 2–10 keV X-ray band, for a "crab-like" X-ray spectrum, which is roughly a powerlaw in photon energy, I(E)=9.5 E-1.1. Very few X-ray sources ever exceed one crab in brightness.

Contents

History

The modern history of the Crab Pulsar begins with the identification of the central star of the nebula in optical light. Focus was made on two stars near the center of the nebula (referred to in the literature as the "north following" and "south preceding" stars). In September 1942, Walter Baade rules out the north following star but finds the evidence inconclusive for the south preceding.[8] Rudolf Minkowski, in the same issue of Astrophysical Journal as Baade, advances spectral arguments claiming the "evidence admits, but does not prove, the conclusion that the south preceding star is the central star of the nebula".[9]

In late 1968, David H. Staelin and Edward C. Reifenstein III reported the discovery of two pulsating radio sources "near the crab nebula that could be coincident with it" using the 300-foot Green Bank radio antenna.[10] They were given the designations NP 0527 and NP 0532. A subsequent study by them including William D. Brundate found that the NP 0532 source is located at the Crab Nebula.[11] A radio source was also reported coincident with the crab nebula in late 1968 by L. I. Matveenko in Soviet Astronomy.[12]

Optical pulsations were reported by Nather, Warner, and Macfarlane in February 1969.[13]

A planetary companion?

In early '70, Curtis proposed the presence of a planetary companion to explain certain variations observed in pulsar timing[14]. Such putative object would have a mass of 0.00001 Solar masses (i.e 0.01 Jupiter masses or 3.3 Earth masses) and be located at 0.3 Astronomical Units from the pulsar. Accounting the age of such article, it's likely this candidate might turn out spurious or at least unconfirmed.

The Crab Pulsar system
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity
b (unconfirmed) ≥3.28 M 0.3  ?  ?

References

  1. ^ NASA (September 19, 2002). "Space Movie Reveals Shocking Secrets of the Crab Pulsar". Press release. http://hubblesite.org/newscenter/archive/releases/2002/24/image/a.  
  2. ^ a b c d ATNF Pulsar Catalogue database entry. See Manchester, R. N.; et al. (2005), "The Australia Telescope National Facility Pulsar Catalogue", Astronomical Journal 129: 1993, doi:10.1086/428488  
  3. ^ Supernova 1054 - Creation of the Crab Nebula
  4. ^ Duyvendak, J. J. L. (1942), "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part I. The Ancient Oriental Chronicles" (pdf), Publications of the Astronomical Society of the Pacific 54: 91, doi:10.1086/125409, http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1942PASP...54...91D&link_type=ARTICLE&db_key=AST&high=48481ee71b05349  
    Mayall, N. U.; Oort, Jan Hendrik (1942), "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part II. The Astronomical Aspects" (pdf), Publications of the Astronomical Society of the Pacific 54: 95, doi:10.1086/125410, http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1942PASP...54...95M&link_type=ARTICLE&db_key=AST&high=48481ee71b05349  
  5. ^ Brecher, K.; et al. (1983), "Ancient records and the Crab Nebula supernova", The Observatory 103: 106, http://adsabs.harvard.edu/abs/1983Obs...103..106B  
  6. ^ Zeilik, Michael; Gregory, Stephen A. (1998), Introductory Astronomy & Astrophysics (4th ed.), Saunders College Publishing, p. 369, ISBN 0030062284  
  7. ^ Supernovae, Neutron Stars & Pulsars
  8. ^ Baade, Walter (1942), "The Crab Nebula", Astrophysical Journal 96: 188, doi:10.1086/144446, http://adsabs.harvard.edu/abs/1942ApJ....96..188B  
  9. ^ Minkowski, Rudolf (1942), "The Crab Nebula", Astrophysical Journal 96: 199, doi:10.1086/144447, http://adsabs.harvard.edu/abs/1942ApJ....96..199M  
  10. ^ Staelin, David H.; Reifenstein, III, Edward C. (1968), "Pulsating radio sources near the Crab Nebula", Science 162 (3861): 1481, doi:10.1126/science.162.3861.1481, PMID 17739779, http://www.jstor.org/stable/1725616  
  11. ^ Reifenstein, III, Edward C.; Staelin, David H.; Brundage, William D. (1969), "Crab Nebula Pulsar NPO527", Physical Review Letters 22 (7): 311, doi:10.1103/PhysRevLett.22.311, http://link.aps.org/abstract/PRL/v22/p311  
  12. ^ Matveenko, L. I. (1968), "Position of a Source of Small Angular Size in the Crab Nebula", Soviet Astronomy 12: 552, http://adsabs.harvard.edu/abs/1968SvA....12..552M  
  13. ^ Nather, R. E.; Warner, B.; Macfarlane, M. (1969), "Optical Pulsations in the Crab Nebula Pulsar", Nature 221: 527, doi:10.1038/221527a0, http://www.nature.com/nature/journal/v221/n5179/abs/221453a0.html  
  14. ^ Curtis (1970), "Pulsar Planetary Systems", The Astrophysical Journal Letters 159: 25–28, doi:10.1086/180471, Bibcode2007MNRAS.381L...1L, http://adsabs.harvard.edu/abs/1970ApJ...159L..25M  

References

  1. ^ NASA (September 19, 2002). "Space Movie Reveals Shocking Secrets of the Crab Pulsar". Press release. http://hubblesite.org/newscenter/archive/releases/2002/24/image/a.  
  2. ^ a b c d ATNF Pulsar Catalogue database entry. See Manchester, R. N.; et al. (2005), "The Australia Telescope National Facility Pulsar Catalogue", Astronomical Journal 129: 1993, doi:10.1086/428488  
  3. ^ Supernova 1054 - Creation of the Crab Nebula
  4. ^ Duyvendak, J. J. L. (1942), "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part I. The Ancient Oriental Chronicles" (pdf), Publications of the Astronomical Society of the Pacific 54: 91, doi:10.1086/125409, http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1942PASP...54...91D&link_type=ARTICLE&db_key=AST&high=48481ee71b05349  
    Mayall, N. U.; Oort, Jan Hendrik (1942), "Further Data Bearing on the Identification of the Crab Nebula with the Supernova of 1054 A.D. Part II. The Astronomical Aspects" (pdf), Publications of the Astronomical Society of the Pacific 54: 95, doi:10.1086/125410, http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1942PASP...54...95M&link_type=ARTICLE&db_key=AST&high=48481ee71b05349  
  5. ^ Brecher, K.; et al. (1983), "Ancient records and the Crab Nebula supernova", The Observatory 103: 106, http://adsabs.harvard.edu/abs/1983Obs...103..106B  
  6. ^ Zeilik, Michael; Gregory, Stephen A. (1998), Introductory Astronomy & Astrophysics (4th ed.), Saunders College Publishing, p. 369, ISBN 0030062284  
  7. ^ Supernovae, Neutron Stars & Pulsars
  8. ^ Baade, Walter (1942), "The Crab Nebula", Astrophysical Journal 96: 188, doi:10.1086/144446, http://adsabs.harvard.edu/abs/1942ApJ....96..188B  
  9. ^ Minkowski, Rudolf (1942), "The Crab Nebula", Astrophysical Journal 96: 199, doi:10.1086/144447, http://adsabs.harvard.edu/abs/1942ApJ....96..199M  
  10. ^ Staelin, David H.; Reifenstein, III, Edward C. (1968), "Pulsating radio sources near the Crab Nebula", Science 162 (3861): 1481, doi:10.1126/science.162.3861.1481, PMID 17739779, http://www.jstor.org/stable/1725616  
  11. ^ Reifenstein, III, Edward C.; Staelin, David H.; Brundage, William D. (1969), "Crab Nebula Pulsar NPO527", Physical Review Letters 22 (7): 311, doi:10.1103/PhysRevLett.22.311, http://link.aps.org/abstract/PRL/v22/p311  
  12. ^ Matveenko, L. I. (1968), "Position of a Source of Small Angular Size in the Crab Nebula", Soviet Astronomy 12: 552, http://adsabs.harvard.edu/abs/1968SvA....12..552M  
  13. ^ Nather, R. E.; Warner, B.; Macfarlane, M. (1969), "Optical Pulsations in the Crab Nebula Pulsar", Nature 221: 527, doi:10.1038/221527a0, http://www.nature.com/nature/journal/v221/n5179/abs/221453a0.html  
  14. ^ Curtis (1970), "Pulsar Planetary Systems", The Astrophysical Journal Letters 159: 25–28, doi:10.1086/180471, Bibcode2007MNRAS.381L...1L, http://adsabs.harvard.edu/abs/1970ApJ...159L..25M  
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