NGC 3227 is an intermediate spiral galaxy that is interacting with the

dwarf elliptical galaxy Dwarf elliptical galaxies, or dEs, are elliptical galaxies that are smaller than ordinary elliptical galaxies. They are quite common in galaxy groups and clusters, and are usually companions to other galaxies. Examples "Dwarf elliptical" galaxie ...

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''. Both galaxies may be found in the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

Leo. It is a member of the NGC 3227 Group of galaxies, which is a member of the

Leo II Groups The Leo II Groups, or Leo II Cloud, are a series of at least 110 galactic clusters and individual galaxies stretching approximately 30 Mly (9.2 Mpc) off the right edge of the Virgo Supercluster. It is located approximately 65 Mly (20 Mpc) to 95 M ...

, a series of galaxies and galaxy clusters strung out from the right edge of the Virgo Supercluster. 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 Gamma Leonis (γ Leonis, abbreviated Gamma Leo, γ Leo), also named Algieba , is a binary star system in the constellation of Leo. In 2009, a planetary companion around the primary was announced. Nomenclature ''γ Leonis'' ( Latini ...

(i.e. Algieba). One

supernova A supernova is a powerful and luminous explosion of a star. It has the plural form supernovae or supernovas, and is abbreviated SN or SNe. This transient astronomical event occurs during the last evolutionary stages of a massive star or when ...

has been observed in NGC 3227: SN 1983U ( type Ia, mag. 12).

Nucleus

NGC 3227 contains a Seyfert nucleus, a type of active galactic nucleus (AGN). 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 An X-ray, or, much less commonly, X-radiation, is a penetrating form of high-energy electromagnetic radiation. Most X-rays have a wavelength ranging from 10 picometers to 10 nanometers, corresponding to frequencies in the range 30&nb ...

emission. 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-year A light-year, alternatively spelled light year, is a large unit of length used to express astronomical distances and is equivalent to about 9.46 trillion kilometers (), or 5.88 trillion miles ().One trillion here is taken to be 1012 ...

s) of the nucleus. An observed change in the shape of the X-ray

spectrum A spectrum (plural ''spectra'' or ''spectrums'') is a condition that is not limited to a specific set of values but can vary, without gaps, across a continuum. The word was first used scientifically in optics to describe the rainbow of colors i ...

in 2000 and 2001 suggests that some of the X-ray absorbing gas is located within 10–100

light-day The light-second is a unit of length useful in astronomy, telecommunications and relativistic physics. It is defined as the distance that light travels in free space in one second, and is equal to exactly . Just as the second forms the basis for ...

s of the nucleus. 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 This is a list of sources of light, the visible part of the electromagnetic spectrum. Light sources produce photons from another energy source, such as heat, chemical reactions, or conversion of mass or a different frequency of electromagnetic ener ...

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.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"

References

* Catalogue of Double and Multiple Galaxies, Erik Holmberg, 1937 * A catalogue of dwarf galaxy candidates around interacting galaxies, Astron. Astrophys., Suppl. Ser., 129, 455-462 (1998) - May(I) 1998, Deeg, H.J. et al. * Long-term variability of the optical emission lines in the nuclear spectrum of the Seyfert galaxy NGC 3227, ''Active Galaxies Newsletter'', No 98, Pronik I., Metik L., May 2005 * Reverberation Measurements of the Inner Radius of the Dust Torus in Nearby Seyfert 1 Galaxies, M. Suganuma et al., Astrophysical Journal, vol 639, March 2006

External links

Glen Youman's Astrophotos of NGC 3226 and NGC 3227Long-term variability of the optical emission lines in the nuclear spectrum of the Seyfert galaxy NGC 3227, Pronik et al., Active Galaxies Newsletter, No. 98
* {{Ngc35 Seyfert galaxies Intermediate spiral galaxies Peculiar galaxies Leo (constellation) 3227 05620 30445 094 17840215