Scientific Results

Optical refinement

In Sulentic et al. (2006) we performed a careful revision of the morphologies for the whole CIG sample based on POSS II (Second Palomar Observatory Sky Survey; Reid et al. 1991) images.


Because of the large number of CIG with CCD images in the latest SDSS releases, morphological types were revised for the CIG sample, among others, with respect to those listed in  Sulentic et al. (2006). This 2012 Release of AMIGA data has been published in the paper  “The AMIGA sample of isolated galaxies X. A first look at isolated galaxy colors” (Fernandez Lorenzo et al. 2012).  for Fernandez Lorenzo et al (2012) we revised those morphologies for all CIG galaxies with Vhel > 1000 km s−1 and CCD images available either from SDSS or our own data (N = 843). For CIG galaxies with Vhel < 1000 km s−1 (N = 57), morphological types were compiled from the bibliography and the mean value used. For N = 134 galaxies with only POSS II data available, a second revision was performed, with minor modifications to the values assigned in Sulentic et al. (2006). For the remaining galaxies for which we were unable to perform any classification, we used data found in the NED and HyperLeda database. Errors in the morphological types were estimated based on the quality of the used images as well as the angular resolution relative to the galaxy size.



There is a general shift in the morphologies with respect to  Sulentic et al. (2006) toward later types by ΔT = 0.2, which we interpret as being caused by the higher resolution provided by CCD images, which reveales smaller bulges. Types (T) were coded following RC3 (see morphological codes in Table 3 of  Fernandez Lorenzo et al. (2012).


PDF File Sulentic et al. (2006) also flagged galaxies that they suspected to be interacting. We now replaced this code by a descriptive one, based also on visual inspection of the optical images, as described below. Code IA= 0 was assigned if no relevant signs of distortions are visible. Code IA =1 corresponds to galaxies seen in the images as asymmetric, lopsided, warped or distorted, with an integral sign shape or tidal feature (tail, bridge, shell). Those galaxies were always treated separately in our analysis, to check whether they present a different behavior from those classified with code 0. Code IA = 2 was assigned if the galaxy was identified as a pair in Verley et al. (2007a) and/or in NED, or if the galaxy looks like a merger or superposition of two galaxies. These galaxies were considered not to be part of the AMIGA sample and are marked differently in the plots.


The new data are presented in Table 1 of PDF File Fernandez Lorenzo et al. (2012) and now all CIG galaxies have a morphological code.