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Astron. Astrophys. 361, 491-499 (2000)

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9. Summary and conclusions

From ROSAT PSPC observations of the dwarf galaxy NGC 3109 we derive 10 X-ray sources which are contained within the HI extent of this galaxy and which have accurate hardness ratios. We classify 2 of these sources as foreground stars, 2 as candidate X-ray binaries and 3 as candidate background AGN. From X-ray spectral fitting we derive for 2 of the AGN total hydrogen column densities which we compare with the HI column densities inferred from 21-cm line measurements. We estimate that the molecular mass fraction of the gas is not larger than [FORMULA]60%. Upcoming spectroscopy of candidate optical counterparts will help to constrain the nature of these objects and help to understand the hydrogen content of NGC 3109. Furthermore, spectroscopy of globular clusters around NGC 3109 will help to trace the enrichment history (i.e. the major star formation episodes) and the kinematics (i.e. total mass) of NGC 3109.

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© European Southern Observatory (ESO) 2000

Online publication: October 2, 2000