Herschel-Planck dust optical-depth and column-density maps: I. Method description and results for Orion

Abstract

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 $0.01\mathrm{mag}<A_K<30\mathrm{mag}$, or $2\times 10^{20}{\mathrm{cm}}^{-2}<N<5\times 10^{23}{\mathrm{cm}}^{-2}$. 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 ${\Sigma }_{\ast }$ follows a simple law ${\Sigma }_{\ast }\propto {\Sigma }_{gas}^{\beta }$, with $\beta \sim 2$.

19 pages, A&A in press. High resolution figures available at http://www.marcolombardi.org/research/recent-papers/orion

References in corpus (5)

• The distance to the Orion Nebula
• What determines the density structure of molecular clouds ? A case study of Orion B with Herschel
• 2MASS wide field extinction maps - I. The Pipe nebula
• NICEST, a near-infrared color excess method tailored for small-scale structures
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Cited by in corpus (6)

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• Molecular clouds have power-law probability distribution functions
• A Herschel [CII] Galactic plane survey III: [CII] as a tracer of star formation
• Star formation in turbulent molecular clouds with colliding flow
• Evolving Molecular Cloud Structure and the Column Density Probability Distribution Function
• Some like it cold: molecular emission and effective dust temperatures of dense cores in the Pipe Nebula