Herschel-Planck dust optical depth and column density maps

II. Perseus^⋆

¹ Leiden Observatory, Niels Bohrweg 2, 2333 CA Leiden, The Netherlands
e-mail: zariem@strw.leidenuniv.nl
² University of Milan, Department of Physics, via Celoria 16, 20133 Milan, Italy
³ University of Vienna, Turkenschanzstrasse 17, 1180 Vienna, Austria
⁴ Harvard-Smithsonian Center for Astrophysics, Mail Stop 72, 60 Garden Street, Cambridge, MA 02138, USA
⁵ Centro de Astrobiología, INTA-CSIC, PO Box 78, 28691 Villanueva de la Canada, Madrid, Spain

Received: 25 May 2015
Accepted: 24 November 2015

Abstract

We present optical depth and temperature maps of the Perseus molecular cloud, obtained combining dust emission data from the Herschel and Planck satellites and 2MASS/NIR dust extinction maps. The maps have a resolution of 36 arcsec in the Herschel regions, and of 5 arcmin elsewhere. The dynamic range of the optical depth map ranges from 1 × 10^-2 mag up to 20 mag in the equivalent K-band extinction. We also evaluate the ratio between the 2.2 μm extinction coefficient and the 850 μm opacity. The value we obtain is close to the one found in the Orion B molecular cloud. We show that the cumulative and the differential area function of the data (which is proportional to the probability distribution function of the cloud column density) follow power laws with an index of respectively ≃−2, and ≃−3. We use WISE data to improve current YSO catalogs based mostly on Spitzer data and we build an up-to-date selection of Class I/0 objects. Using this selection, we evaluate the local Schmidt law, Σ_YSO ∝ Σ_gas^β, showing that β = 2.4 ± 0.6. Finally, we show that the area-extinction relation is important for determining the star-formation rate in the cloud, which is in agreement with other recent works.