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تسجيل مستخدم جديدVelocity-resolved [CII] emission and [CII]/FIR Mapping along Orion with Herschel
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We present the first 7.5x11.5 velocity-resolved map of the [CII]158um line toward the Orion molecular cloud-1 (OMC-1) taken with the Herschel/HIFI instrument. In combination with far-infrared (FIR) photometric images and velocity-resolved maps of the H41alpha hydrogen recombination and CO J=2-1 lines, this data set provides an unprecedented view of the intricate small-scale kinematics of the ionized/PDR/molecular gas interfaces and of the radiative feedback from massive stars. The main contribution to the [CII] luminosity (~85%) is from the extended, FUV-illuminated face of the cloud G_0>500, n_H>5x10^3 cm^-3) and from dense PDRs (G_0~10^4, n_H~10^5 cm^-3) at the interface between OMC-1 and the HII region surrounding the Trapezium cluster. Around 15% of the [CII] emission arises from a different gas component without CO counterpart. The [CII] excitation, PDR gas turbulence, line opacity (from [13CII]) and role of the geometry of the illuminating stars with respect to the cloud are investigated. We construct maps of the [CII]/FIR and FIR/M_Gas ratios and show that [CII]/FIR decreases from the extended cloud component (10^-2-10^-3) to the more opaque star-forming cores (10^-3-10^-4). The lowest values are reminiscent of the [CII] deficit seen in local ultra-luminous IR galaxies hosting vigorous star formation. Spatial correlation analysis shows that the decreasing [CII]/FIR ratio correlates better with the column density of dust through the molecular cloud than with FIR/M_Gas. We conclude that the [CII] emitting column relative to the total dust column along each line of sight is responsible for the observed [CII]/FIR variations through the cloud.
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The [CII] fine-structure transition at 158 micron is frequently the brightest far-infrared line in galaxies. Due to its low ionization potential, C+ can trace the ionized, atomic, and molecular phases of the ISM. We present velocity resolved [CII] an
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We present the first results of an observational programme undertaken to map the fine structure line emission of singly ionized carbon ([CII] 157.7409 micron) over extended regions using a Fabry Perot spectrometer newly installed at the focal plane o
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