5 Conclusions

We have conducted a search for radio continuum emission from young stellar objects in the globule DC 303.8-14.2 using the Australia Telescope Compact Array. We detected an unresolved source which is coincident positionally with the IRAS 13036-7644, a deeply embedded object driving a bipolar molecular outflow. Based solely on the spectral index, we can not make a firm distinction between non-thermal and optically thin thermal free-free emission.

None of the other sources has an associated IRAS point source. The source #3 is located on the ¹²CO outflow component, and it has a non-thermal spectral index, $\alpha=-0.7$. For the source #2, also within the cloud, we can derive only a lower limit for the spectral index, $\alpha>1.1$, which indicates thermal emission. Not much of its nature can be said at this point, but it is a good candidate for being a YSO, possibly a Class 0 protostar, within the cloud.

The origin of ionization in these low-luminosity objects has been studied on the basis of the observed fluxes at 3 and 6 cm. The spectral index and the observed fluxes of the IRAS source are consistent with models where the source of emission is circumstellar gas shocked and ionized by the stellar wind (Torrelles et al. 1985) or a mass accreting envelope (Felli et al. 1982). The accretion model of Felli et al. (1982), when applied with physical parameters typical for a low-mass YSO, produces much more flux than what is observed. Either the mass accretion is exceedingly low, or, more probably, the spherical, free-fall model is not applicable here. The shock-induced model has more unknown parameters, but it can produce a flux which is compatible with observations.

Our observations have added one more object to the list of continuum emission from low-luminosity embedded YSOs that are powering molecular outflows. In order to deduce the real source of emission, continuum observations at a wider spectral region are necessary. In addition, high angular resolution observations capable of resolving the structure of the sources would be most instructive.

Acknowledgements

We wish to thank the ATCA staff for operating the telescope during our observations. The work of K.L. has been supported by the Vilho, Yrjö and Kalle Väisälä foundation of the Finnish Academy of Science and Letters, and by the Finnish Academy through grant No. 1011055, which is gratefully acknowledged. We thank the referee for useful comments.