The Cygnus Allscale Survey of Chemistry and Dynamical Environments: CASCADE: Overview and first results toward DR20 from the Max Planck IRAM Observatory program (MIOP)

TL;DR

This paper presents the initial results of the CASCADE survey, mapping large-scale star-forming regions in Cygnus X with NOEMA and IRAM, revealing complex kinematics, temperature structures, and turbulence in the DR20 site.

Contribution

It provides the first detailed overview and initial findings of the CASCADE survey, connecting large-scale interstellar material with small-scale dense cores in Cygnus X.

Findings

Multiple large-scale cloud flows onto cores identified.

Deuterated DCO+ emission localized in cold regions below 20 K.

Spatial power spectra suggest high turbulence and active star formation.

Abstract

Context: While star formation on large molecular cloud scales and on small core and disk scales has been investigated intensely over the past decades, the connection of the large-scale interstellar material with the densest small-scale cores has been a largely neglected field. Methods: Using NOEMA and the IRAM 30\,m telescope, we mapped large areas (640\,arcmin$^2$) of the archetypical star formation complex Cygnus X at 3.6\,mm wavelengths in line and continuum emission. Results: The scope and outline of The Cygnus Allscale Survey of Chemistry and Dynamical Environments (CASCADE) is presented. We then focus on the first observed subregion in Cygnus X, namely the DR20 star formation site, which comprises sources in a range of evolutionary stages from cold pristine gas clumps to more evolved ultracompact H{\sc ii} regions. The data covering cloud to cores scales at a linear spatial resolution of $<5000$\,au reveal several kinematic cloud components that are likely part of several large-scale flows onto the central cores. The temperature structure of the region is investigated by means of the HCN/HNC intensity ratio and compared to dust-derived temperatures. We find that the deuterated DCO$^+$ emission is almost exclusively located toward regions at low temperatures below 20\,K. Investigating the slopes of spatial power spectra of dense gas tracer intensity distributions (HCO$^+$, H$^{13}$CO$^+$, and N$_2$H$^+$), we find comparatively flat slopes between $-2.9$ and $-2.6$, consistent with high Mach numbers and/or active star formation in DR20.