The HP2 Survey

IV. The Pipe nebula: Effective dust temperatures in dense cores^★,★★

¹ Department for Astrophysics, University of Vienna, Türkenschanzstraße 17, 1180 Vienna, Austria
e-mail: birgit.hasenberger@univie.ac.at
² University of Milan, Department of Physics, Via Celoria 16, 20133 Milan, Italy
³ Centre for Astrophysics Research, University of Hertfordshire, Hatfield AL10 9AB, UK
⁴ Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge MA 02138, USA
⁵ Leiden Observatory, Leiden University, PO Box 9513, NL-2300 RA Leiden, The Netherlands

Received: 21 December 2017
Accepted: 17 June 2018

Abstract

Multi-wavelength observations in the sub-millimeter regime provide information on the distribution of both the dust column density and the effective dust temperature in molecular clouds. In this study, we created high-resolution and high-dynamic-range maps of the Pipe nebula region and explored the value of dust-temperature measurements in particular towards the dense cores embedded in the cloud. The maps are based on data from the Herschel and Planck satellites, and calibrated with a near-infrared extinction map based on 2MASS observations. We have considered a sample of previously defined cores and found that the majority of core regions contain at least one local temperature minimum. Moreover, we observed an anti-correlation between column density and temperature. The slope of this anti-correlation is dependent on the region boundaries and can be used as a metric to distinguish dense from diffuse areas in the cloud if systematic effects are addressed appropriately. Employing dust-temperature data thus allows us to draw conclusions on the thermodynamically dominant processes in this sample of cores: external heating by the interstellar radiation field and shielding by the surrounding medium. In addition, we have taken a first step towards a physically motivated core definition by recognising that the column–density–temperature anti-correlation is sensitive to the core boundaries. Dust-temperature maps therefore clearly contain valuable information about the physical state of the observed medium.