Part of Coma Cluster including NGC 4889, NGC 4886, NGC 4874, NGC 4921, NGC 4911, 4921, NGC 4923, IC 4051 and many, many more in the constellation Coma Berenices

Annotated B/W image

Most popular cross-identifications for Coma Cluster are: ABELL 1656, UGCl 276, ZwCl 1257.1+2806

The center of the Coma Cluster is just between the two massive elliptical galaxies NGC 4889 and NGC 4874 with coordinates:

RA (2000): 12h 59m 48.7s

Dec (2000): +27° 58′50

(Coma Cluster center position reference: 1989ApJS...70....1A)

It is most probably to one to count more galaxies than stars in that image because the Coma Cluster contains over 1000 identified galaxies. The image shows only the central part of the Coma Cluster and it spans 35 x 35 (arcmin) across as the cluster diameter itself is about 319 arcminutes (5 degrees). The brightest galaxies in the Coma Cluster NGC 4889 and NGC 4874 dominate the image center. It is now believed that all massive galaxies contain a supermassive black hole (SMBH) at their center (Magorrian et al. 1998; Richstone et al. 1998; Ferrarese & Ford 2005). The mentioned two galaxies NGC 4889 and NGC 4874 have SMBH in their cores.

Several attempts to identify nearby groups and clusters of galaxies have been made in the past decades. The evolution of the galaxies and their current observed properties are a consequence of the combined effects of self-regulated internal processes and external ones related with the environment where they lie. It is well established in literature that high density environments, like clusters of galaxies, present a larger fraction of early-type galaxies than the field (e.g. Baldry et al. 2006; Rasmussen et al. 2012; Finn et al. 2018).

In Houghton et al. (2013) were presented three slow rotators in the cluster: NGC4889, NGC4874, and NGC4860. When groups/clusters merge, their central galaxies also merge owing to their relatively high masses and low velocities and form massive slow rotators. Due to this, the number fraction of slow rotators tend to remain constant as group and clusters grow to form massive galaxy clusters such as the Coma cluster. (Shetty et al., 2020).

The Coma cluster (Abell 1656) is the most massive nearby (z ∼ 0.023) cluster to us. The Coma Cluster now is known to be dynamically very active. It has two D (depleted core) galaxies near the center (NGC 4874 and NGC 4889) and its spatial distribution shows several subclumps and overdensities (Fitchett & Webster 1987; Mellier 1988; Ulmer et al. 1994; Merritt & Tremblay 1994; Conselice & Gallagher 1998; Mendelin & Binggeli 2017). A formation scenario that is currently contemplated for the Coma cluster is a merger of two sub-clusters or groups associated with the two D galaxies, NGC 4874 and NGC 4889, possibly after their second core crossing (Briel, Henry, & Böhringer 1992; Watt et al. 1992; Davis & Mushotzky 1993; Colless & Dunn 1996; Arnaud et al. 2001; Neumann et al. 2003; Adami et al. 2005b; Gerhard et al. 2007).

Zwicky et al. (1957) was the first to report the existence of a diffuse intergalactic light (ICL) in the core of the Coma cluster, detected by direct photography, to be later confirmed by Gunn (1969). The radial color gradient of the stellar populations in the galaxies triggered the hypothesis that this diffuse light could be primarily formed by stars tidally stripped from galaxy collisions in the cluster core. The discovery of low surface brightness tidal features in the ICL supported this idea (Trentham & Mobasher 1998; Gregg & West 1998; Adami et al. 2005a).

Charts and image details obtained from Astrometry.net

Image and FOV details

RC 12" Astrograph (IRIDA South dome)

Imaging details

ASA 12" Astrograph (IRIDA North dome)

Imaging details