NGC 4151

NGC 4151

Image of NGC 4151 from the 0.8m Schulman Telescope at the Mount Lemmon SkyCenter
Observation data (J2000 epoch)
Constellation Canes Venatici
Right ascension 12h 10m 32.6s[1]
Declination +39° 24 21[1]
Redshift 0.003262[2]
995 ± 3 km/s[1]
Distance 19 Mpc (62×10^6 ly) [3]
Apparent magnitude (V) 11.5[1]
Characteristics
Type (R')SAB(rs)ab,[1] Sy1[2]
Apparent size (V) 6.4 × 5.5[1]
Other designations
UGC 7166,[1] PGC 38739[1]

NGC 4151 is an intermediate spiral Seyfert galaxy with weak inner ring structure located 19 megaparsecs (62 million light-years) from Earth[3] in the constellation Canes Venatici. The galaxy was first mentioned by William Herschel on March 17, 1787; it was one of the two Seyfert galaxies described in the paper [4] which defined the term. It is one of the nearest galaxies to Earth to contain an actively growing supermassive black hole;[5] it was speculated that the nucleus may host a binary black hole, with about 40 million and about 10 million solar masses respectively, orbiting with a 15.8-year period.[6] This is, however, still a matter of active debate.

Some astronomers nickname it the "Eye of Sauron" from its appearance.[7]

X-ray source

NGC 4151. X-rays (blue), optical data (yellow), radio observation (red)
Astronomers using data from the European Space Agency’s XMM-Newton satellite have found a long-sought X-ray signal from NGC 4151. When the black hole’s X-ray source flares, its accretion disk reflects the emission about half an hour later.

X-ray emission from NGC 4151 was apparently first detected on December 24, 1970, with the X-ray observatory satellite Uhuru,[8] although the observation spanned an error-box of 0.56 square degrees and there is some controversy as to whether UHURU might not have detected the BL Lac object 1E 1207.9 +3945, which is inside their error box - the later HEAO 1 detected an X-ray source of NGC 4151 at 1H 1210+393,[9] coincident with the optical position of the nucleus and outside the error box of.[8]

To explain the X-ray emission two different possibilities have been proposed:[10]

See also

References

  1. 1 2 3 4 5 6 7 8 "Results for NGC 4151". NASA/IPAC Extragalactic Database. Retrieved 2007-03-27.
  2. 1 2 "NGC 4151". SIMBAD Astronomical Database. Retrieved 2014-06-06.
  3. 1 2 W. M. Keck Observatory (2014-11-26). "'Eye of Sauron' Provides New Way of Measuring Distances to Galaxies". W. M. Keck Observatory. Retrieved 2014-11-27.
  4. C. K. Seyfert (1943). "Nuclear Emission in Spiral Nebulae". Astrophysical Journal. 97: 28–40. Bibcode:1943ApJ....97...28S. doi:10.1086/144488.
  5. "NGC 4151: An active black hole in the "Eye of Sauron"". Astronomy magazine. 2011-03-11. Retrieved 2011-03-14.
  6. Bon; Jovanović; Marziani; Shapovalova; et al. (2012). "The First Spectroscopically Resolved Sub-parsec Orbit of a Supermassive Binary Black Hole". The Astrophysical Journal. 759 (2): 118–125. arXiv:1209.4524Freely accessible. Bibcode:2012ApJ...759..118B. doi:10.1088/0004-637X/759/2/118.
  7. Chandra X-ray Observatory (10 March 2011). "NGC 4151: An Active Black Hole in the "Eye of Sauron"". Chandra X-ray Center.
  8. 1 2 Gursky H; Kellogg EM; Leong C; Tananbaum H; et al. (Apr 1971). "Detection of X-Rays from the Seyfert Galaxies NGC 1275 and NGC 4151 by the UHURU Satellite". Ap J. 165 (4): L43–8. Bibcode:1971ApJ...165L..43G. doi:10.1086/180713.
  9. Wood KS; Meekins JF; Yentis DJ; Smathers HW; et al. (December 1984). "The HEAO A-1 X-ray source catalog". Ap J Suppl Ser. 56 (12): 507–649. Bibcode:1984ApJS...56..507W. doi:10.1086/190992.
  10. Chandra X-Ray Observatory (2011-03-10). "The 'Eye of Sauron'". NASA. Retrieved 2011-03-14.
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