Using the IRAM 30 m radio telescope we have mapped the tidal arm feature south–east of NGC 3077 where we recently detected molecular gas in the CO ( J =1 \to 0 ) and ( 2 \to 1 ) transitions .
We find that the molecular gas is much more extended than previously thought ( several kpc ) .
The CO emission can be separated into at least 3 distinct complexes with equivalent radii between 250 pc and 700 pc and all well confined over a narrow range in velocity – the newly detected complexes therefore range among the largest molecular complexes in the local universe .
For one complex we have also obtained a CO ( 3 \to 2 ) spectrum using the KOSMA 3 m radio telescope ; utilizing an LVG model we find that the kinetic temperature for this complex must be about 10 K , and the H _ { 2 } volume density between 600 and 10000 cm ^ { -3 } .
Mass estimates based on virialization yield a total mass for the complexes of order 2 - 4 \times 10 ^ { 7 } M _ { \odot } , i.e .
more than the estimated molecular mass within NGC 3077 itself .
This implies that interactions between galaxies can efficiently remove heavy elements and molecules from a galaxy and enrich the intergalactic medium .
A comparison of the distribution of H I and CO shows no clear correlation .
However , CO is only found in regions where the H I column density exceeds 1.1 \times 10 ^ { 21 } cm ^ { -2 } .
H I masses for the molecular complexes mapped are of the same order as the corresponding molecular masses .
Because the intergalactic pressure is most likely too low to confine the complexes we conclude that they are gravitationally bound .
Since the tidal arm with its molecular complexes has all the ingredients to form stars in the future , we are thus presumably witnessing the birth of a dwarf galaxy .
This process could be important for the formation of dwarf galaxies especially at larger look–back times in the universe where galaxy interactions may have been more frequent .