NGC 3227 explained

NGC 3227
Type:SAB(s) pec[1]
Constellation Name:Leo
Epoch:J2000
Dist Ly:77 ± 9 Mly (24 ± 3 Mpc)[2]
Z:1157 ± 3 km/s
Appmag V:11.1
Size V:5.4 × 3.6
Names:UGC 5620, PGC 30445, Arp 94

NGC 3227 is an intermediate spiral galaxy that is interacting with the dwarf elliptical galaxy NGC 3226. The two galaxies are one of several examples of a spiral with a dwarf elliptical companion that are listed in the Atlas of Peculiar Galaxies.[3] Both galaxies may be found in the constellation Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the Leo II Groups, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster.[4]

Sir William Herschel already recognised them as a 'double nebula' and they were jointly listed as Holm 187 in the Catalogue of Double and Multiple Galaxies and as Arp 94 in the Atlas of Peculiar Galaxies. Amateur telescopes can discern them but require magnification of about 100 times. They are situated 50 east of the well-known double star system Gamma Leonis (i.e. Algieba).

One supernova has been observed in NGC 3227: SN 1983U (type Ia, mag. 12).[5] [6]

Nucleus

NGC 3227 contains a Seyfert nucleus, a type of active galactic nucleus (AGN).[7] Such Seyfert nuclei typically contain supermassive black holes. This object has an estimated mass of .

As is typical of many AGN, the nucleus of NGC 3227 has been identified as a source of variable X-ray emission.[8] [9] [10] [11] [12] This variability occurs on time scales ranging from a few hours to a few months. The variability may be caused by variations in the density or ionization of gas and dust near the AGN that absorb the X-ray emission. A substantial amount of the X-ray-absorbing gas may lie within 0.4 parsec (1.3 light-years) of the nucleus. An observed change in the shape of the X-ray spectrum in 2000 and 2001 suggests that some of the X-ray absorbing gas is located within 10–100 light-days of the nucleus.[13]

The luminosity of the nucleus reached a maximum in 1977 when evidence suggesting long-lived one-sided or two-sided gas streams was obtained. X-ray radiation of the central accretion disc is reprocessed in one to two days to be re-emitted in the optical spectrum. Infra-red light emission from the hot dust torus lags optical light emission from the nucleus by about 20 days in NGC 3227. The temperature of the dust torus is estimated at 1500 K to 1800 K in NGC 3227 and similar galaxies.

This galaxy was studied by the Multicolor Active Galactic Nuclei Monitoring 2m telescope.[14]

References

External links

Notes and References

  1. Web site: NASA/IPAC Extragalactic Database . Results for NGC 3227 . 2006-10-12.
  2. J. L. Tonry . 4 . A. Dressler . J. P. Blakeslee . E. A. Ajhar . A. B. Fletcher . G. A. Luppino . M. R. Metzger . C. B. Moore . The SBF Survey of Galaxy Distances. IV. SBF Magnitudes, Colors, and Distances . Astrophysical Journal . 2001 . 546 . 2 . 681–693 . 2001ApJ...546..681T . 10.1086/318301 . astro-ph/0011223 . 17628238 .
  3. H. Arp . Atlas of Peculiar Galaxies . Astrophysical Journal Supplement . 1966 . 14 . 1–20 . 1966ApJS...14....1A . 10.1086/190147.
  4. Web site: The Leo III Groups . Atlas of the Universe . 2010-11-27 . July 22, 2012 . https://archive.today/20120722223749/http://www.atlasoftheuniverse.com/galgrps/leoii.html . live .
  5. https://www.wis-tns.org/object/1983U Transient Name Server entry for SN 1983U.
  6. http://www.cbat.eps.harvard.edu/iauc/03800/03887.html Circular No 3887 Central Bureau for Astronomical Telegrams.
  7. L. C. Ho . A. V. Filippenko . W. L. W. Sargent . A Search for "Dwarf" Seyfert Nuclei. III. Spectroscopic Parameters and Properties of the Host Galaxies . Astrophysical Journal Supplement . 1997 . 112 . 2 . 315–390 . 1997ApJS..112..315H . 10.1086/313041 . astro-ph/9704107 . 17086638 .
  8. A. F. Tennant . R. F. Mushotzky . The absence of rapid X-ray variability in active galaxies . Astrophysical Journal . 1983 . 264 . 92–104 . 1983ApJ...264...92T . 10.1086/160576. 2060/19820022328 . 117087588 . free .
  9. T. J. Turner . K. A. Pounds . The EXOSAT spectral survey of AGN . . 1989 . 240 . 4 . 833–880 . 1989MNRAS.240..833T . 10.1093/mnras/240.4.833. free .
  10. A. Ptak . 4 . T. Yaqoob . P. J. Serlemitsos . R. Mushotzky . C. Otani . Rapid X-ray spectral variability in NGC 3227 . Astrophysical Journal . 1994 . 436 . L31–L34 . 1994ApJ...436L..31P . 10.1086/187626.
  11. S. Komossa . H. Fink . Evidence for a dusty warm absorber in NGC 3227? . Astronomy and Astrophysics . 1997 . 327 . 483–492 . 1997A&A...327..483K. astro-ph/9707003 .
  12. P. Gondoin . A. Orr . D. Lumb . H. Siddiqui . XMM-Newton observations of the Seyfert 1 galaxy NGC 3227 . Astronomy and Astrophysics . 2003 . 397 . 3 . 883–890 . 2003A&A...397..883G . 10.1051/0004-6361:20021574. free .
  13. G. Lamer . P. Uttley . I. M. McHardy . An absorption event in the X-ray light curve of NGC 3227 . Monthly Notices of the Royal Astronomical Society . 2003 . 342 . 3 . L41–L45 . 2003MNRAS.342L..41L . 10.1046/j.1365-8711.2003.06759.x. free . astro-ph/0305130 . 16031703 .
  14. http://www.journals.uchicago.edu/doi/abs/10.1086/499326 The Astrophysical Journal, 639:46–63, 2006 March 1 "Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies"

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