Herschel Reveals Massive Cold Clumps in NGC 7538

TL;DR

This study uses Herschel observations to identify and analyze cold, massive starless and early-stage star-forming clumps in NGC 7538, revealing detailed structures and candidate regions for high-mass star formation.

Contribution

First Herschel-based survey of NGC 7538 identifying cold massive clumps and filamentary structures, with detailed characterization of potential high-mass star-forming regions.

Findings

Identified 13 cold, massive starless or early-stage star-forming clumps.

Revealed a highly filamentary structure in NGC 7538.

Produced the most complete imaging of an evacuated ring in the region.

Abstract

We present the first overview of the Herschel observations of the nearby high-mass star-forming region NGC 7538, taken as part of the Herschel imaging study of OB Young Stellar objects (HOBYS) Key Programme. These PACS and SPIRE maps cover an approximate area of one square degree at five submillimeter and far-infrared wavebands. We have identified 780 dense sources and classified 224 of those. With the intention of investigating the existence of cold massive starless or class 0-like clumps that would have the potential to form intermediate- to high-mass stars, we further isolate 13 clumps as the most likely candidates for followup studies. These 13 clumps have masses in excess of 40 M_sun and temperatures below 15 K. They range in size from 0.4 pc to 2.5 pc and have densities between 3x10^3 cm^-3 to 4x10^4 cm^-3. Spectral energy distributions are then used to characterize their energetics and evolutionary state through a luminosity-mass diagram. NGC 7538 has a highly filamentary structure, previously unseen in the dust continuum of existing submillimeter surveys. We report the most complete imaging to date of a large, evacuated ring of material in NGC 7538 which is bordered by many cool sources.