We present near-infrared ( NIR ) adaptive optics imaging obtained with VLT/NACO and optical spectroscopy from the Southern African Large Telescope ( SALT ) of a luminous infrared galaxy ( LIRG ) IRAS 19115-2124 .
These data are combined with archival HST imaging and Spitzer imaging and spectroscopy , allowing us to study this disturbed interacting/merging galaxy , dubbed the Bird , in extraordinary detail .
In particular , the data reveal a triple system where the LIRG phenomenon is dominated by the smallest of the components .

One nucleus is a regular barred spiral with significant rotation , while another is highly disturbed with a surface brightness distribution intermediate to that of disk and bulge systems , and hints of remaining arm/bar structure .
We derive dynamical masses in the range 3–7 \times 10 ^ { 10 } { M } _ { \odot } for both .
The third component appears to be a 1–2 \times 10 ^ { 10 } { M } _ { \odot } mass irregular galaxy .
The total system exhibits H II galaxy-like optical line ratios and strengths , and no evidence for AGN activity is found from optical or mid-infrared data .
The star formation rate is estimated to be \sim 190 { M _ { \odot } yr ^ { -1 } } .
We also report a search for supernovae from NIR images separated by 5 months and search for super star cluster candidates .
We detect outflowing gas from the Bird mostly in the range 100–300 km s ^ { -1 } using Na I D absorption features .
Overall , the Bird shows kinematic , dynamical , and emission line properties typical for cool ultra luminous IR galaxies .
However , the interesting features setting it apart for future studies are its triple merger nature , and the location of its star formation peak – the strongest star formation , as revealed by Spitzer imaging , does not come from the two major K -band nuclei , but from the third irregular component .
This is in contrast to the conventional view that the ( U ) LIRG phases are powered by infalling gas to the major nuclei of the merging spiral galaxies .
Aided by simulations , we discuss scenarios where the irregular component is on its first high-speed encounter with the more massive components .