Shakhbazian compact galaxy groups

Abstract

Abstract. In 1995 we commenced a detailed spectral and photometric study of Shakhbazian compact groups. In this paper the results on groups ShCG 181, ShCG 344, ShCG 361, and ShCG 362 are presented. The redshifts of member galaxies in groups and the radial velocity dispersions, the results of the surface photometry in BVR, the profiles of the surface brightness versus semi-major axis a (or a 1/4 ) and the twisting position angle versus semi-major axis of galaxies, virial masses, luminosities and mass-to-luminosity ratios, and the crossing times of groups are given. It is shown that some members of groups are in the process of interaction. On the basis of the results obtained in this and previous works, the general properties of thirteen ShCGs are discussed.

Spectroscopy and photometry of ShCG 191 - Abell 1097

“…Since the images of some members are very compact, sometimes it is very difficult to differ them from those of stars. However, follow-up detailed study of ShCGs showed that the overhelming majority of objects in these groups are indeed galaxies (Tiersch et al 2002;Tovmassian et al 2003aTovmassian et al , 2003bTovmassian et al , 2004Tovmassian et al , 2005aTovmassian et al , 2005b. Oleak et al (1995) showed that these groups have a "cigar"-like prolate spheroid space configuration.…”

Photometric observations of nine Shakhbazian compact groups

“…A large number of interacting galaxies are detected among ShCG members [14,[15][16][17][18][19][20][21][22][23]. A large number of interacting galaxies are detected among ShCG members [14,[15][16][17][18][19][20][21][22][23].…”

“…Spectral and photographic observations of a large number of ShCG groups have been made by Tiersch et al [14 and references therein] and Tovmassian et al [15][16][17][18][19][20][21][22][23]. It was shown that the majority of the candidate group members were galaxies with accordant radial velocities (usually < 1000 km s -1 ).…”

The properties of the heterogeneous Shakhbazyan groups of galaxies in the SDSS

“…Rich group, with very well‐defined overdensity and elongated appearance. Its physical nature was proved by detailed photometric and spectroscopic studies by Fasano & Bettoni (1994) and Tovmassian et al (2004). Tovmassian et al (2004) measure a rather low spatial density compared the other SHK groups.…”

“…Furthermore, even though some contamination by stars is indeed present, many of the objects initially suspected to be stars were found to be galaxies. The extensive and detailed studies by Tiersch, (Tiersch 1976; Tiersch et al 1993, 1994, 1995, 1996a, 1996a,b, 2002), Tovmassian (Tovmassian et al 1998, 1999a,b; Tovmassian & Tiersch 2001; Tovmassian et al 2003a,b, 2004, 2005a,b,c, 2006, 2007) and collaborators of a subset of 44 groups have shown that SHK groups form a rather intriguing class of physically bound and moderately compact structures. The spatial densities of SHK groups found in these works, span a wide range: from slightly higher than those of loose groups (10–10 2 gal Mpc −3 ) up to values comparable to the cores of rich clusters or HCGs (10 4 – 10 5 gal Mpc −3 ) for m ≲ 19 mag.…”