Producción Científica Profesorado

Galaxy evolution in nearby loose groups - II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud

Gabbasov -, Ruslan


Marino, A.; Plana, H.; Rampazzo, R.; Bianchi, L.; Rosado, M.; Bettoni, D.; Galletta, G.; Mazzei, P.; Buson, L.; Ambrocio-Cruz, P.; Gabbasov, R. F. Galaxy evolution in nearby loose groups - II. Photometric and kinematic characterization of USGC U268 and USGC U376 group members in the Leo cloud. (2013) MNRAS.428..476M


This paper is the second of a series of papers in which we are exploring the coevolution of galaxies and groups in the local Universe, by adopting a multiwavelength approach. Here, we present the photometric and kinematic characterization of two groups, USGC U268 and USGC U376 (U268 and U376 hereafter), which are located in different regions of the Leo cloud. We revisit the group membership, using results from recent redshift surveys, and we investigate their substructures. U268, which is composed of 10 catalogued members and 11 new added members, has a small fraction (?24 per cent) of early-type galaxies (ETGs). U376 has 16 catalogued members plus eight new added members, with ?38 per cent of ETGs. We find that there are significant substructures in both groups, which suggests that they are likely to be accreting galaxies. U268 is located in a more loose environment than U376. For each member galaxy, broad-band integrated and surface photometry have been obtained in far-ultraviolet (FUV) and near-ultraviolet (NUV) with the Galaxy Evolution Explorer (GALEX), and in the u, g, r, i and z (Sloan Digital Sky Survey) bands. H? imaging and two-dimensional high-resolution kinematical data have been obtained using the scanning Fabry?Pérot interferometer (PUMA) at the 2.12-m telescope at San Pedro Mártir (Baja California, Mexico). We have improved the galaxy classification and we have detected morphological and kinematical distortions that might be connected either to ongoing and/or past interaction/accretion events or to environmental-induced secular evolution. U268 appears to be more active than U376, with a large fraction of galaxies showing interaction signatures (60 per cent versus 13 per cent). The presence of bars among late-type galaxies is ?10 per cent in U268 and ?29 per cent in U376. The cumulative distribution of the FUV?NUV colours of galaxies in U268 is significantly different from that in U376, with galaxies in U268 being bluer than those in U376. In the (FUV?r versus Mr) and (NUV?r versus Mr) planes, no members of U268 are found in the red sequence; even ETGs lie in the blue sequence, or in the ?green valley?. Most (i.e. 80 per cent) of the early-type members in U376 inhabit the red sequence. A large fraction of galaxies, of different morphological types, are located in the green valley, while the blue sequence is underpopulated compared with U268.

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