KT Mon has been considered as a classical nova in 1942 based on its light curve and spectroscopy. However, we noticed a previously overlooked unusual feature: the early presence of high excitation emission lines such as HeII. We examine three new possibilities (recurrent nova, WZ Sge-type dwarf nova, X-ray transient). We have found that the possibilities of a WZ Sge-type dwarf nova or an X-ray transient are more consistent with the modern knowledge, although the possibility of a recurrent nova (or a nova with an unusual spectroscopic evolution) is not completely excluded. If KT Mon is a WZ Sge-type dwarf nova, the system should have a brown dwarf. If KT Mon is an X-ray transient, the system is a good candidate for the nearest black hole. In all possibilities, we can expect a recurrent outburst in meaningfully near future (10-100 yr depending on the classification). Detailed observations during the possible next outburst, as well as deep quiescent observations, for this obscure object are strongly recommended.
Acknowledgements
This work is partly supported by a grant-in aid [13640239 (TK), 14740131 (HY)] from the Japanese Ministry of Education, Culture, Sports, Science and Technology. This research has made use of the Digitized Sky Survey producted by STScI, the ESO Skycat tool, the VizieR catalogue access tool.
Copyright ESO 2002