ter the nature of these “baby galaxies.” From
Gemini spectroscopy, we were able to detect
the chemical elements already present in these
galaxies and determined they are more metalrich than typical dwarf galaxies (de Mello et al.,
2012).
Figure 1.
GALEX NUV image
measuring 10’ × 10’
with H I contours. Four
HCG 100 members are
marked as ”a, b, c, and
d“. Intragroup objects
are circled (radius =
8 arcseconds) and
numbered. VLA NH I
contours are 0.6, 1.2, 2.1,
3.6, 4.4, 5.1, 5.9, 6.6, and
7.4 ×1020 cm−2 (Verdes
Montenegro et al. 2006).
North is up and east is to
the left. Objects 3 and 4
from de Mello et al. (2008)
are the “Baby Galaxies”
identified in the NUV
image and for the first
time seen in the optical
r-Band with Gemini.
In 2008 we started a pilot project with Gemini to
explore the nature of a dozen UV sources found
in the H I tidal tail of a group of galaxies known
as Hickson Compact Group 100 (HCG 100). Located 249 million light-years away, this group
is formed by a bright central spiral galaxy (HCG
100a), an irregular galaxy with an optical tidal
tail (HCG 100b), a late-type barred spiral (HCG
100c), a late-type edge-on spiral (HCG 100d),
and a really long H I tidal tail extending more
than 424,000 light-years from the interacting
galaxies. In de Mello et al. (2008), we present
GALEX images of this group, where we identified a dozen UV sources located in the vicinity
of the H I tail. When we compared their UV light
to the ones of stellar populations from theoretical models, we estimated that they are only a
few million years old.
Gemini Baby Galaxies
With the Gemini Multi-Object Spectrograph
(GMOS), we confirmed that two of the largest UV sources lie at the same distance as the
Hickson group and therefore they may belong
to this interacting system. With Gemini optical (r) images, we discovered the knotty morphology of these objects (Figure 1), just like
one would expect from young galaxies. But
GMOS data provided us with one more piece
of information that helped us understand bet-
22
GeminiFocus
Therefore, due to their morphology and chemical composition, we suggested