# Surveys of Clumps, Cores, and Condensations in Cygnus X: I. a New Catalog of ~0.1 pc Massive Dense Cores

## TL;DR

This study presents a comprehensive catalog of ~0.1 pc massive dense cores in Cygnus X, revealing their physical properties, classifications, and potential as initial high-mass star formation sites, significantly expanding previous surveys.

## Contribution

It provides the largest, most complete catalog of MDCs in Cygnus X, with new classifications and insights into their role in high-mass star formation.

## Key findings

- Identified 151 MDCs with detailed physical properties.
- Discovered a high proportion of IR-quiet MDCs, suggesting different star formation stages.
- Found 26 starless MDCs as potential initial high-mass star formation sites.

## Abstract

Using infrared to (sub)millimeter data from Spitzer, Herschel, the James Clerk Maxwell Telescope, and the IRAM 30-m telescope, we conducted an unbiased survey of the massive dense cores (MDCs) in the Cygnus X molecular cloud complex, aimed at characterizing the physical conditions of high-mass star formation (HMSF) at ~0.1 pc scales. We created 5 deg times 6 deg images of the 70-1200 um dust continuum, gas column density, and dust temperature of Cygnus X. A spatial relation between the dense regions (Av > 15) and the developed HII regions was found, indicating the impact of the latter on the global structures of Cygnus X. With a 35-Msun mass threshold implied by HMSF signposts, we identified 151 MDCs with sizes of ~0.1 pc, masses of 35-1762 Msun, and temperatures of 8-35 K. Our MDC sample is statistically complete in Cygnus X and is three times larger than that in Motte et al. (2007). The MDCs were classified into IR-bright/IR-quiet ones based on their mid-infrared fluxes and a large "IR-quiet" proportion (90%) was found in our sample. Two possible scenarios were proposed to interpret this: accelerated HMSF and the incapability of HMSF of the IR-quiet MDCs. We also found 26 starless MDCs by their lack of compact emissions at 21-70 um wavelengths, of which the most massive ones are probably the best candidates of initial HMSF sites in Cygnus X.