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Observations towards L1630 in the Orion B molecular cloud, comprising the iconic Horsehead Nebula, allow us to study the interplay between stellar radiation and a molecular cloud under relatively benign conditions, that is, intermediate densities and an intermediate UV radiation field. Contrary to the well-studied Orion Molecular Cloud 1 (OMC1), which hosts much harsher conditions, L1630 has little star formation. We aim to relate the [CII] fine-structure line emission to the physical conditions predominant in L1630 and compare it to studies of OMC1. The [CII] $158,mumathrm{m}$ emission from an area of $12 times 17$ in L1630 was observed using the upGREAT instrument onboard SOFIA. Of the [CII] emission from the mapped area 95%, $13,L_{odot}$, originates from the molecular cloud; the adjacent HII region contributes only 5%, that is, $1,L_{odot}$. From comparison with other data (CO (1-0)-line emission, far-infrared (FIR) continuum studies, emission from polycyclic aromatic hydrocarbons (PAHs)), we infer a gas density of the molecular cloud of $n_{mathrm{H}}sim 3cdot 10^3,mathrm{cm^{-3}}$, with surface layers, including the Horsehead Nebula, having a density of up to $n_{mathrm{H}}sim 4cdot 10^4,mathrm{cm^{-3}}$. The temperature of the surface gas is $Tsim 100,mathrm{K}$. The average [CII] cooling efficiency within the molecular cloud is $1.3cdot 10^{-2}$. The fraction of the mass of the molecular cloud within the studied area that is traced by [CII] is only $8%$. Our PDR models are able to reproduce the FIR-[CII] correlations and also the CO (1-0)-[CII] correlations. Finally, we compare our results on the heating efficiency of the gas with theoretical studies of photoelectric heating by PAHs, clusters of PAHs, and very small grains, and find the heating efficiency to be lower than theoretically predicted, a continuation of the trend set by other observations.
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
Aims: To investigate properties of [CII]158 $mu$m emission of RCW36 in a dense filamentary cloud. Methods: [CII] observations of RCW36 covering an area of ~30 arcmin$times$30 arcmin were carried out with a Fabry-P{e}rot spectrometer aboard a 100-cm b
We have mapped six molecular cloud cores in the Orion A giant molecular cloud (GMC), whose kinetic temperatures range from 10 to 30 K, in CCS and N2H+ with Nobeyama 45 m radio telescope to study their chemical characteristics. We identified 31 intens
We performed new comprehensive $^{13}$CO($J$=2--1) observations toward NGC 2024, the most active star forming region in Orion B, with an angular resolution of $sim$100 obtained with NANTEN2. We found that the associated cloud consists of two independ
We present the discovery of expanding spherical shells around low to intermediate-mass young stars in the Orion A giant molecular cloud using observations of $^{12}$CO (1-0) and $^{13}$CO (1-0) from the Nobeyama Radio Observatory 45-meter telescope.