Herschel Reveals Massive Cold Clumps in NGC 7538
  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.
