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Orion as seen by Herschel and Planck

posted Mar 31, 2014, 1:40 PM by Marco Lombardi   [ updated Mar 31, 2014, 2:11 PM ]
A&A in press, by Lombardi M., Hervé B., Alves J., and C.J. Lada   
We present high-resolution, high dynamic range column-density and color-temperature maps of the Orion complex using a combination of Planck dust-emission maps, Herschel dust-emission maps, and 2MASS NIR dust-extinction maps. The column-density maps combine the robustness of the 2MASS NIR extinction maps with the resolution and coverage of the Herschel and Planck dust-emission maps and constitute the highest dynamic range column-density maps ever constructed for the entire Orion complex, covering 0.01 mag < AK < 30 mag, or 2×1020 cm−2 < N < 5×1023 cm−2. We determined the ratio of the 2.2 microns extinction coefficient to the 850 microns opacity and found that the values obtained for both Orion A and B are significantly lower than the predictions of standard dust models, but agree with newer models that incorporate icy silicate-graphite conglomerates for the grain population. We show that the cloud projected pdf, over a large range of column densities, can be well fitted by a simple power law. Moreover, we considered the local Schmidt-law for star formation, and confirm earlier results, showing that the protostar surface density Σ∗ follows a simple law Σ∗Σgasβ, with β~2.
Combined optical-depth and temperature map of Orion A and B.  The image is based on high-resolution Herschel data, where available, and on Planck data, elsewhere.