Abstract
This paper presents the properties of X-ray sources in the regions of NGC 2023 and NGC 2024 observed with ASCA. We found 14 point-like sources in the NGC 2023 field. In the NGC 2024 field, on the other hand, we found extended X-ray emission in the central dust lane of NGC 2024, and resolved 5 point-like sources around the nebula. From the positional coincidence and moderate column density of NH ∼ 1.6×1022 H cm−2, the extended source is mostly attributable to an integrated emission from X-ray emitting young stellar objects (YSOs) found with ROSAT. However, the plasma temperature of ∼ 4 keV is higher than the ROSAT results as well as those of usual YSOs. Possible counterparts have been found for the other resolved sources, except two; one has large absorption at low energies and the other has moderate absorption. The plasma temperatures and luminosities from the point sources, except for an O-type star ζ Ori and a star exhibiting X-ray flares, are estimated to be ∼ 1-5 keV and 1030.6−1031.5 erg s−1 in the 0.5−10.0 keV energy band (assuming the distance of 400 pc), respectively. We found no X-ray peak at the position of a Class 0 protostar, NGC 2023-MM1.
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