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Astron. Astrophys. 361, 500-506 (2000)

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6. Conclusions

Our new observations have revealed extensive molecular gas in the tidal arms near NGC 3077. The CO emission is much more extended than previously thought - the detected complexes range among the most extended complexes in the local universe. We have detected at least three independent complexes of molecular gas. The complexes are most probably gravitationally bound and have formed in situ . For the largest of the complexes our multi-transition CO study shows that the gas must be cold ([FORMULA]10 K), thus massive star formation is not going on at a significant level. Whether or not the chain of blue stars (the `Garland') found in this region (Karachentsev et al. 1985a , 1985b) is associated with the molecular complex is an open question which is currently under investigation by us.

The fact that CO is found in tidal arms implies that galaxy interactions can efficiently remove enriched material from a galaxy's body hence influencing it's chemical history. This also has important implications for the chemical enrichment of the intergalactic medium (IGM), especially at larger look-back times in the universe where galaxy interactions may have been more frequent.

Since the tidal arm with its newly discovered molecular complexes has all the ingredients to form stars in the future (i.e., atomic and molecular gas), our new observation confirm our previous speculation (Walter & Heithausen 1999) that we are witnessing the birth of a dwarf galaxy where star formation might start in the near future. We are therefore in the fortunate situation to witness a process which may have created a substantial number of today's dwarf galaxies in the past.

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© European Southern Observatory (ESO) 2000

Online publication: October 2, 2000