gingadan.com

NGC 474 (Elliptical Galaxy)


Home > Galaxy - Cluster > NGC474
Down
Movie

NGC 474
Elliptical Galaxy (楕円銀河)
Gx S0


別名 (Other names)
PGC 4801, UGC 864, Arp 227

明るさ (Brightness)
11.3等級

星座 (Constellation)
うお座 (Psc) (Pisces)


距離 (Distance)
1億光年 (100 million light-years)

NGC 474 is an elliptical galaxy located 100 million light years from the Earth in the constellation Pisces.

NGC 474 (Elliptical Galaxy) : Picture

Galaxy NGC 474: Cosmic Blender
Galaxy NGC 474: Cosmic Blender
(C) P.-A. Duc (CEA, CFHT), Atlas 3D Collaboration
What's happening to galaxy NGC 474? The multiple layers of emission appear strangely complex and unexpected given the relatively featureless appearance of the elliptical galaxy in less deep images. The cause of the shells is currently unknown, but possibly tidal tails related to debris left over from absorbing numerous small galaxies in the past billion years. Alternatively the shells may be like ripples in a pond, where the ongoing collision with the spiral galaxy just above NGC 474 is causing density waves to ripple though the galactic giant. Regardless of the actual cause, the above image dramatically highlights the increasing consensus that at least some elliptical galaxies have formed in the recent past, and that the outer halos of most large galaxies are not really smooth but have complexities induced by frequent interactions with -- and accretions of -- smaller nearby galaxies. The halo of our own Milky Way Galaxy is one example of such unexpected complexity. NGC 474 spans about 250,000 light years and lies about 100 million light years distant toward the constellation of Pisces.

Shell Galaxies
Shell Galaxies in Pisces
(C) Stephen Leshin
This colorful cosmic skyscape features a peculiar system of galaxies cataloged as Arp 227 some 100 million light-years distant. Swimming within the boundaries of the constellation Pisces, Arp 227 consists of the two galaxies prominent on the left; the curious shell galaxy NGC 474 and its blue, spiral-armed neighbor NGC 470. The faint, wide arcs or shells of NGC 474 could have been formed by a gravitational encounter with neighbor NGC 470. Alternately the shells could be caused by a merger with a smaller galaxy producing an effect analogous to ripples across the surface of a pond. Remarkably, the large galaxy on the right hand side of the deep image, NGC 467, appears to be surrounded by faint shells too, evidence of another interacting galaxy system. Intriguing background galaxies are scattered around the field that also includes spiky foreground stars. Of course, those stars lie well within our own Milky Way Galaxy. The field of view spans 25 arc minutes or about 1/2 degree on the sky.

Galaxy NGC 474: Cosmic Blender
Galaxy NGC 474: Cosmic Blender
(C) Mischa Schirmer

NGC 474 NGC 474
NGC 474
(C) P.-A. Duc
NGC 474
(C) Mischa Schirmer
Up
Up

NGC 474 (Elliptical Galaxy) : Movie

Up
Home > Galaxy - Cluster > NGC474
Up

gingadan.com ブログパーツ