NGC 2264 and NGC 7000/IC 5070 revisited - A new search for emission H-alpha stars

A slitless spectrographic search for H-alpha emission stars in NGC 2264 and NGC 7000/IC 5070 has revealed 18 new examples, most of which are presumably T Tau stars. An examination of all known T Tau stars in these fields has uncovered no events of the FU Ori type, except for that of V1057 Cyg. The incompleteness of the search as a function of magnitude and H-alpha strength is estimated by comparison with Herbig's survey (1954, 1958). It is found that for B less than 16.0, about 80% of the potential H-alpha emitters will be found in a survey with this equipment. These results, combined with an estimate of the volume occupied by the association in NGC 2264, yield a volume density of stars that show H-alpha emission (either now, or eventually if the area is surveyed repeatedly) brighter than B = 19 of about 1.6/cu pc.

Перевод пока недоступен