The Forgotten Quadrant Survey. ${}^{12}$CO and ${}^{13}$CO (1-0) survey of the Galactic Plane in the range 220°$<l<$240° -2.5°$<b<$0°

Abstract

We present the Forgotten Quadrant Survey (FQS), an ESO large project that used the 12m antenna of the Arizona Radio Observatory to map the Galactic Plane in the range 220°$<l<$240°and -2.5°$<b<$0°, both in ${}^{12}$CO(1-0) and ${}^{13}$CO(1-0), at a spectral resolution of 0.65 km s${}^{-1}$ and 0.26 km s${}^{-1}$. Our dataset allows us to easily identify how the molecular dense gas is organised at different spatial scales: from the giant clouds with their denser filamentary networks, down to the clumps and cores that host the newborn stars and to obtain reliable estimates of their key physical parameters. We present the first release of the FQS data and discuss their quality. Spectra with 0.65 km s${}^{-1}$ velocity channels have a noise ranging from 0.8 K to 1.3 K for ${}^{12}$CO(1-0) and from 0.3 K to 0.6 K for ${}^{13}$CO(1-0). In this paper, we used the ${}^{12}$CO(1-0) spectral cubes to produce a catalogue of 263 molecular clouds. This is the first selfconsistent, statistical catalogue of molecular clouds of the outer Galaxy, obtained with a subarcminute spatial resolution and therefore able to detect not only the classical giant molecular clouds, but also the small clouds and to resolve the cloud structure at the subparsec scale up to a distance of a few kpc. We found two classes of objects: structures with size above a few parsecs that are typical molecular clouds and may be self-gravitating, and subparsec structures that cannot be in gravitational equilibrium and are likely transient or confined by external pressure. We used the ratio between the Herschel H${}_2$ column density and the integrated intensity of the CO lines to calculate the CO conversion factor and we found mean values of (3.3$\pm$1.4)$\times 10^{20}$ cm${}^{-2}$(K km s${}^{-1}{)}^{-1}$ and (1.2$\pm$0.4)$\times 10^{21}$ cm${}^{-2}$(K km s${}^{-1}{)}^{-1}$, for ${}^{12}$CO(1-0) and ${}^{13}$CO(1-0), respectively.

16 pages, 17 figures, accepted for publication in Astronomy and Astrophysics

References in corpus (12)

• Theory of Star Formation
• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• Structural Analysis of Molecular Clouds: Dendrograms
• Physical properties of molecular clouds for the entire Milky Way disk
• Bias-free Measurement of Giant Molecular Cloud Properties
• The observed spiral structure of the Milky Way
• FOREST Unbiased Galactic plane Imaging survey with the Nobeyama 45-m telescope (FUGIN) I: Project Overview and Initial Results
• Trigonometric Parallaxes of Star Forming Regions in the Perseus Spiral Arm
• Parallaxes of Star Forming Regions in the Outer Spiral Arm of the Milky Way
• Massive 70 micron quiet clumps II: non-thermal motions driven by gravity in massive star formation?
• Thermal balance and comparison of gas and dust properties of dense clumps in the Hi-GAL survey
• VIALACTEA knowledge base homogenizing access to Milky Way data

Cited by in corpus (20)

• The SEDIGISM survey: first data release and overview of the Galactic structure
• CHIMPS2: Survey description and ${}^{12}$CO emission in the Galactic Centre
• Molecular gas distribution perpendicular to the Galactic plane
• Molecular Clouds in the Second Quadrant of the Milky Way Mid-plane from l$=$104$.{}^{\circ }$75 to l=119$.{}^{\circ }$75 and b=$-$5$.{}^{\circ }$25 to b=5$.{}^{\circ }$25
• Gas Column Density Distribution of Molecular Clouds in the Third Quadrant of the Milky Way
• Molecular cloud catalogue from ${}^{13}$CO(1-0) data of the Forgotten Quadrant Survey
• Kinetic tomography of the Galactic plane within 1.25 kiloparsecs from the Sun. The interstellar flows revealed by HI and CO line emission and 3D dust
• OGHReS: Star formation in the Outer Galaxy ($\ell =250^{\circ }$-$280^{\circ }$)
• Three isotopologues CO survey of Molecular Clouds in the CMa OB1 complex
• Cloud properties across spatial scales in simulations of the interstellar medium
• Distributions and Physical Properties of Molecular Clouds in the Third Galactic Quadrant: $l$ = [219.75, 229.75]${}^{\circ }$ and $b$ = [-5.25, 5.25]${}^{\circ }$
• Planck CO revisited: Improved CO line emission maps from Planck space mission observations
• A revised view of the Canis Major stellar overdensity with DECam and Gaia: new evidence of a stellar warp of blue stars
• The warm and dense Galaxy - tracing the formation of dense cloud structures out to the Galactic Center
• Investigating the Impact of Metallicity on Star Formation in the Outer Galaxy. I. VLT/KMOS Survey of Young Stellar Objects in Canis Major
• The Hierarchical Dynamical State of Molecular Gas from 3 to 300 pc in NGC 253
• Shear-gravity transition determines the steep velocity dispersion-size relation in molecular clouds: confronting analytical formula with observations
• Far-infrared line emission from the outer Galaxy cluster Gy 3-7 with SOFIA/FIFI-LS: Physical conditions and UV fields
• Extended atomic carbon around molecular clouds
• Anisotropy in the carbon monoxide (CO) line emission across the Milky Way's disk