Stellar Population Properties of ETGs in Compact Groups of Galaxies
  We present results on the study of the stellar population in Early-Type
galaxies (ETGs) belonging to 151 Compact Groups (CGs). We also selected a field
sample composed of 846 ETGs to investigate environmental effects on galaxy
evolution. We find that the dependences of mean stellar ages, [Z/H] and
[$\alpha$/Fe] on central stellar velocity dispersion are similar, regardless
where the ETG resides, CGs or field. When compared to the sample of centrals
and satellites from the literature, we find that ETGs in GCs behave similarly
to centrals, especially those embedded in low-mass haloes ($M_{h} < 10^
{12.5}M_{\odot}$). Except for the low-mass limit, where field galaxies present
a Starforming signature, not seen in CGs, the ionization agent of the gas in CG
and field galaxies seem to be similar and due to hot, evolved low-mass stars.
However, field ETGs present an excess of H$\alpha$ emission relative to ETGs in
CGs. Additionally, we performed a dynamical analysis, which shows that CGs
present a bimodality in the group velocity dispersion distribution - a high and
low-$\sigma$ mode. Our results indicate that high-$\sigma$ groups have a
smaller fraction of spirals, shorter crossing times, and a more luminous
population of galaxies than the low $\sigma$ groups. It is important to
emphasize that our findings point to a small environmental impact on galaxies
located in CGs. The only evidence we find is the change in gas content,
suggesting environmentally-driven gas loss.
