broad survey of Hα emission-line stars in the Orion region by making use of the 4
objective prism of the Schmidt telescope (Wiramihardja et al. 1989). They surveyed
a sky area of 325 square degrees and identified 1220 Hα emission-line objects,
including 804 new detections and 29 nonstellar objects. These stars are widely
distributed on the western side of the Orion molecular clouds. The distribution of
all Hα emission stars, including both previously and newly identified stars, is
illustrated in Fig. 6.6, along with the contours of the molecular clouds (Nakano
et al. 1995). In this figure, the aggregation of emission-line stars on the western side
of the main molecular cloud is remarkable. The emission-line stars in this part are
mostly identified by the Kiso survey, and this group is free from molecular clouds
and OB stars in the Orion region. For around 30 stars in this group, spectroscopic
observations were carried out by Kogure, Ogura Katsuo, and others at the
Fig. 6.6 Distribution of all Hα emission-line stars in 1995, overlapped on the contour of molecular
clouds. (Nakano et al. 1995)
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objective prism of the Schmidt telescope (Wiramihardja et al. 1989). They surveyed
a sky area of 325 square degrees and identified 1220 Hα emission-line objects,
including 804 new detections and 29 nonstellar objects. These stars are widely
distributed on the western side of the Orion molecular clouds. The distribution of
all Hα emission stars, including both previously and newly identified stars, is
illustrated in Fig. 6.6, along with the contours of the molecular clouds (Nakano
et al. 1995). In this figure, the aggregation of emission-line stars on the western side
of the main molecular cloud is remarkable. The emission-line stars in this part are
mostly identified by the Kiso survey, and this group is free from molecular clouds
and OB stars in the Orion region. For around 30 stars in this group, spectroscopic
observations were carried out by Kogure, Ogura Katsuo, and others at the
Fig. 6.6 Distribution of all Hα emission-line stars in 1995, overlapped on the contour of molecular
clouds. (Nakano et al. 1995)
6.3 Optical and Infrared Observatories
145