Ha-excess sources spectroscopic follow-up

However, while this approach usually yields very few spurious detections, it may fail to select intrinsically faint and/or rare Ha-excess sources. In order to obtain a more complete representation of the heterogeneous emission line populations, we recently developed a technique to find outliers relative to nearby objects in the colour-magnitude diagram (CMD-based selection).

By combining position -based and CMD-based selections, we built an updated catalogue of Ha-excess candidates in the northern Galactic Plane. Here we present spectroscopic follow-up observations and classification of 114 objects from this catalogue, that enable us to test our novel selection method. Out of the 70 spectroscopically confirmed Ha emitters in our sample, 15 were identified only by the CMD-based selection, and would have been thus missed by the classic position-based technique.