Tidal Streams in NGC 474, NGC 470, NGC 467 (Arp 227) - Interacting Early-Type Galaxies (ETGs) in Pisces

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© Velimir Popov & Emil Ivanov 2013

The images illustrate the variety of low surface brightness structures that show up around these galaxies: long tidal tails and shells, telling us about past major mergers.

NGC 474 is the huge elliptical galaxy with the numerous tidal tails. NGC 470 is the spiral galaxy next to it, located at the same distance (~100 million light years). The faint, wide arcs or shells of NGC 474 could have been formed by a gravitational encounter with neighbor NGC 470.

NGC 467 to the lower right is also caught in an ongoing multiple-merger process, and has a distance of about 250 million light years. Hence, this system is intrinsically as big as or even bigger than NGC 474. NGC 467, appears to be surrounded by faint shells too, evidence of another interacting galaxy system.

PGC 4755 is the bluish irregular object at the very bottom of the field of view at the same distance as NGC 467. Other background galaxies are also represented in the image.

Briеfly adapted information and figure courtesy:

Probing the mass assembly of massive nearby galaxies with deep imaging (P.-A. Duc et. al)

This image (APOD from 5.01.2014 - courtesy P. -A. Duc) is the result of very deep optical images in the g’,r’ and i’ bands obtained with the large field of view camera MegaCam installed on the CFHT. The observations are carried out as part of several projects: ATLAS3D, the Next Generation Virgo Cluster Survey

According to a popular scenario supported by numerical models, the mass assembly and growth of massive galaxies, in particular the Early-Type Galaxies (ETGs), is mainly due to the accretion of multiple gas-poor satellites. Thus we obtain extremely deep optical images of the few galaxies and their satellites. The images allow to detect the relics of past collisions such as faint stellar tidal tails as well as the much extended stellar halos which keep the memory of the last episodes of galactic accretion.

Object details for NGC 474

Right Ascension 01:20:6.78 (h:m:s)
Declination +03:24:55.6 (deg:m:s)
Distance 100 000 (kly)
Apparent Dimension 6.165 x 5.011 (arc min)

Image details


Center of field RA 01:19:42.926 (h:m:s)
Center of field DE +03:23:55.398 (deg:m:s)
Size 24.4 x 24.4 (arcmin)
Pixel scale: 1.04 (arcsec/pixel)
Orientation: North is up
Charts and image details obtained from Astrometry.net

RC 12"

Optic(s): RC 12" with Astro-Physics corrector @ f/5 (RC)
Mount: ASA DDM85 Premium
Camera: ATIK 4000 M
Filters: Astronomik II: Lum, Red, Green, Blue
Dates/Times: 4 - 12.10.2013
Location: IRIDA Observatory, BG, longitude: E 24 44' 18", latitude: N 41 41' 42"
Exp. Details: L: 80x15 min; R: 11x15 min; G:11x15 min; B: 11x15 min;
  Bin 1, Total Exposure Time - 1695 min (28:15 hours)
More details: Dark and flat frames reduction
Processing: PixInsight / PS
Copyright: Velimir Popov and Emil Ivanov 2013. All Rights Reserved
e-mail: info@irida-observatory.org
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