Eruptive Phenomena in Early Stellar Evolution: New Class of IX Oph Type Eruptions (IXor)

Amplitudes of FUor and EXor eruptions are comparable, while duration of the high stage of their brightness differs by 2 orders of magnitude (having order of 10 2 and 10 0 years for FUors and EXors, respectively). There had been no reports on observations of eruptions with intermediate duration of order of 10 1 years in young stars so far. Using available data banks, the author carried out a search of young stars with eruptions of order of 10 1 duration. The search criteria were developed and in the stars IX Oph and V1057 Cyg eruptions of required duration were discovered. It is proposed to call found eruptions as IX Oph type eruptions (IXor). Identification results and general characteristics of IXor eruption observed in V1057 Cyg are presented and discussed.