The RMS Survey: ${}^{13}$CO observations of candidate massive YSOs in the northern Galactic plane

Abstract

Context: The Red MSX Source (RMS) survey is an ongoing multi-wavelength observational programme designed to return a large, high-resolution mid-infrared colour-selected sample of massive young stellar objects. Aims: A critical part of our follow-up programme is to conduct 13CO molecular line observations in order to determine kinematic distances to all of our MYSO candidates. These distances will allow us to identify and remove nearby low-mass YSOs and help in identifying evolved stars which are weak CO emitters. Method: We have used the 15 m James Clerk Maxwell Telescope (JCMT), the 13.7 m telescope of the Purple Mountain Observatory (PMO), the 20 m Onsala telescope and the 22m Mopra telescope to conduct molecular line observations towards 508 MYSOs candidates located in the 1st and 2nd Quadrants. Results: We detect 13CO emission towards 780 RMS sources which corresponds to approximately 84% of those observed (911). A total of 2595 emission components are detected above 3sigma level (typically T^*_{\rm{A}} > 0.3K), with multiple components being observed towards the majority of these sources -- 520 sources (~56%) -- with an average of ~4 molecular clouds detected along each line of sight. We have used archival CS (J=2-1) and maser velocities to resolve the component multiplicity towards 175 sources (~20%) and have derived a criterion which is used to identify the most likely component for a further 191 multiple component sources. Combined with the single component detections we have obtained unambiguous kinematic velocities for 638 of the 780 MYSOs candidates towards which CO is detected (~80% of the detections). Using the Galactic rotation curve we calculate kinematic distances for all detected components.

13 pages and 9 figures, accepted for publication in A&A. Includes a large table and figure to be made available via CDS

References in corpus (4)

• The Boston University-Five College Radio Astronomy Observatory Galactic Ring Survey
• The earliest phases of high-mass star formation: a 3 square degree millimeter continuum mapping of Cygnus X
• The RMS Survey: Radio observations of candidate massive YSOs in the southern hemisphere
• The RMS Survey: Mid-Infrared Observations of Candidate Massive YSOs in the Southern Hemisphere

Cited by in corpus (13)

• ATLASGAL --- properties of a complete sample of Galactic clumps
• ATLASGAL --- towards a complete sample of massive star forming clumps
• The Luminosity Functions and Timescales of MYSOs and Compact HII regions
• A String of Radio Emission Associated with IRAS 16562-3959: A Collimated Jet Emanating from a Luminous Massive YSO
• Diversity of chemistry and excitation conditions in the high-mass star forming complex W33
• SEDIGISM-ATLASGAL: Dense Gas Fraction and Star Formation Efficiency Across the Galactic Disk
• A Galactic survey of radio jets from massive protostars
• Chemical evolution of Red MSX Sources in the southern sky
• WISE Discovery of Mid-infrared Variability in Massive Young Stellar Objects
• Probing the Global Dust Properties and Cluster Formation Potential of the Giant Molecular Cloud G148.24+00.41
• A census of young stellar objects in two line-of-sight star forming regions toward IRAS 22147+5948 in the outer Galaxy
• Investigating the morphology and CO gas kinematics of Sh2-112 region
• Herschel Hi-GAL imaging of massive young stellar objects