We present 70 and 160 μm Herschel science demonstration images of a field in the Orion A molecular cloud that contains the prototypical Herbig-Haro objects HH 1 and 2, obtained with the Photodetector Array Camera and Spectrometer (PACS). These observations demonstrate Herschel's unprecedented ability to study the rich population of protostars in the Orion molecular clouds at the wavelengths where they emit most of their luminosity. The four protostars previously identified by Spitzer 3.6-40 μm imaging and spectroscopy are detected in the 70 μm band, and three are clearly detected at 160 μm. We measure photometry of the protostars in the PACS bands and assemble their spectral energy distributions (SEDs) from 1 to 870 μm with these data, Spitzer spectra and photometry, 2MASS data, and APEX sub-mm data. The SEDs are fit to models generated with radiative transfer codes. From these fits we can constrain the fundamental properties of the protostars. We find luminosities in the range 12-84 L⊙ and envelope densities spanning over two orders of magnitude. This implies that the four protostars have a wide range of envelope infall rates and evolutionary states: two have dense, infalling envelopes, while the other two have only residual envelopes. We also show the highly irregular and filamentary structure of the cold dust and gas surrounding the protostars as traced at 160 μm. © ESO 2010

This work is based on observations made with the Herschel Space Observatory, a European Space Agency Cornerstone Mission with significant participation by NASA, and with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. Support for the Herschel and Spitzer analysis was provided by NASA through awards issued by JPL/Caltech. We are grateful to Barbara Whitney and her collaborators for making their radiative transfer code available to the community

Fischer, William J. et al.-- Full list of authurs: Fischer, W. J.; Megeath, S. T.; Ali, B.; Tobin, J. J.; Osorio, M.; Allen, L. E.; Kryukova, E.; Stanke, T.; Stutz, A. M.; Bergin, E.; Calvet, N.; di Francesco, J.; Furlan, E.; Hartmann, L.; Henning, T.; Krause, O.; Manoj, P.; Maret, S.; Muzerolle, J.; Myers, P.; Neufeld, D.; Pontoppidan, K.; Poteet, C. A.; Watson, D. M.; Wilson, T.

Peer reviewed