Eleven out of twelve BCDGs in our sample are dominated by an old stellar population. This rules out the "genuine young system'' hypothesis for those BCDGs (in the sense of "primeval'' character). In the case of Mk 600, the emission is dominated by the starburst even in the near-infrared. Nonetheless, Mk 600 follows the same color-color relations as the other BCDGs, hence an evolved stellar population must be present, although its emission is hidden by the starburst.
The BCDGs follow the same color-metallicity relation as the Galactic globular clusters, indicating that the underlying stellar population of these BCDGs is dominated by a stellar population similar to those of the globular clusters given the metallicity of the stars.
We found that BCDGs host significant AGB populations in addition to a cosmologicaly old red giant star population. The origin of the AGBs remains uncertain, i.e. whether they come from older busts, or from a very low continuous star formation.
The photometric classification described in Papers I & II still holds in the near infrared, but the dichotomy between the two classes as measured by the infrared photometric parameters is less obvious. Also, we found that some peculiar cases, like MK 996 showing an almost pure exponential in the J band, and UM 465 showing a significant r1/4 law envelope in all three bands. We find that the r1/4BCDGs follow a tight relation between the absolute magnitude and the radius, but the small BCDGs show a systematic excess of light for their effective size compared to the larger BCDGs. On the contrary, the exponential BCDGs show a loose relation between the absolute magnitude and the radius, but they don't show any size dependent color "excess''.
Copyright ESO 2001