First results from the Herschel Gould Belt Survey in Taurus

TL;DR

This paper presents initial Herschel observations of the Taurus region, introducing a new source-finding algorithm, and provides evidence that starless and prestellar cores are part of a continuous evolutionary sequence.

Contribution

It introduces the Cardiff Source-finding Algorithm (CSAR) and demonstrates its effectiveness in analyzing hierarchical structures in star-forming regions.

Findings

Herschel data reveals a continuous population of clumps between starless and prestellar cores.

Hierarchical structures range from 0.024 to 2.7 pc in size.

Supports the theory that unbound clumps and prestellar cores are part of the same evolutionary sequence.

Abstract

The whole of the Taurus region (a total area of 52 sq. deg.) has been observed by the Herschel SPIRE and PACS instruments at wavelengths of 70, 160, 250, 350 and 500 {\mu}m as part of the Herschel Gould Belt Survey. In this paper we present the first results from the part of the Taurus region that includes the Barnard 18 and L1536 clouds. A new source-finding routine, the Cardiff Source-finding AlgoRithm (CSAR), is introduced, which is loosely based on CLUMPFIND, but that also generates a structure tree, or dendrogram, which can be used to interpret hierarchical clump structure in a complex region. Sources were extracted from the data using the hierarchical version of CSAR and plotted on a mass-size diagram. We found a hierarchy of objects with sizes in the range 0.024-2.7 pc. Previous studies showed that gravitationally bound prestellar cores and unbound starless clumps appeared in different places on the mass-size diagram. However, it was unclear whether this was due to a lack of instrumental dynamic range or whether they were actually two distinct populations. The excellent sensitivity of Herschel shows that our sources fill the gap in the mass-size plane between starless and pre-stellar cores, and gives the first clear supporting observational evidence for the theory that unbound clumps and (gravitationally bound) prestellar cores are all part of the same population, and hence presumably part of the same evolutionary sequence (c.f. Simpson et al. 2011).