INFRARED SPECTROSCOPIC STUDY OF NGC-2024

Near-infrared spectrophotometric observations of the obscured H II region NGC 2024 are presented. The data include Bry line and 3.29 μm intensity distributions in an area of about 2′.5 (R.A.) × 1′.5 (decl.), together with measurements in several positions of the Bra line, the He I (2.058 μm) line, and 3.07 μm ice-band absorption. The spectrophotometry of NGC 2024 IRS 2 is also presented. The integrated flux of the Bry line in the region observed is estimated, after a correction for foreground absorption of Aυ ∼ 11 mag, as about 9 × 10-18 W cm-2, at least 3 times as large as that of IRS 2. The Bry map has a general similarity to available radio continuum maps, especially in the peak region at around 20″ south of IRS 2, but farther south Bry emission seems to be heavily obscured. The 3.29 μm band emission, which is strongest at about 55″ south of IRS 2, has an elongated distribution along the east-west direction. We also show that the extended continuum emission in near-infrared wavelengths can be interpreted by small hot grains with a typical temperature of ∼ 1000 K. By combining these observations, we discuss the nature of exciting stars, which are probably of early B types.