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, i.e. intermediate densities and an intermediate UV radiation field. We have analyzed SOFIA/upGREAT observations of the [CII] 158 um emission from a 12'x17' region, illuminated by the nearby star system sigma Ori. We compared the observations with new CO (1-0) observations of the molecular gas obtained by IRAM, with IRAC studies of the PAH emission from the PDR, H alpha observations of the ionized gas, and with existing far-IR continuum studies using Herschel/PACS and SPIRE data that track the dust properties and trace the radiation field. This wealth of data allows us to identify the emission from the ionized gas, neutral PDR, and molecular cloud, and derive global heating efficiencies and their dependence on the local conditions.
[CII] Emission from L1630 in the Orion B Molecular Cloud