Stellar Systems in the direction of the Hickson Compact Group 44 - I. Low Surface Brightness Galaxies

ESCUDERO, C. G.; SMITH CASTELLI, A. V.; FAIFER, F. R.

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2016 vol. 596 p. 1 - 8

0004-6361

Context. In spite of the numerous studies of low-luminosity galaxies indifferent environments, there is still no consensus about theirformation scenario. In particular, a large number of galaxies displayingextremely low-surface brightnesses have been detected in the last year,and the nature of these objects is under discussion. Aims. In this paperwe report the detection of two extended low-surface brightness (LSB)objects (mueff_g´~27 mag) found, in projection, next to NGC 3193 and inthe zone of the Hickson Compact Group (HCG) 44, respectively. Methods.We analyzed deep, high-quality, GEMINI-GMOS images with ELLIPSE withinIRAF in order to obtain their brightness profiles and structuralparameters. We also search for the presence of globular clusters (GC) inthese fields. Results. We have found that, if these LSB galaxies were atthe distances of NGC 3193 and HCG 44, they would show sizes andluminosities similar to those of the ultra-diffuse galaxies (UDGs) foundin the Coma cluster and other associations. In that case, their sizeswould be rather larger than those displayed by the Local Group dwarfspheroidal (dSph) galaxies. We have detected a few unresolved sources inthe sky zone occupied by these galaxies showing colors and brightnessestypical of blue globular clusters. Conclusions. From the comparison ofthe properties of the galaxies presented in this work, with those ofsimilar objects reported in the literature, we have found that LSBgalaxies display sizes covering a quite extended continous range (reff ~0.3 - 4.5 kpc), in contrast to "normal" early-type galaxies, which showsreff ~ 1.0 kpc with a low dispersion. This fact might be pointing todifferent formation processes for both types of galaxies.