Carbon Monoxide Observations Toward Star Forming Regions in the Outer Scutum-CentaurusSpiral Arm

The Outer Scutum-Centaurus arm (OSC) is the most distant molecular spiral arm known in the Milky Way. The Scutum-Centaurus spiral arm is posited to start at the end of the Galactic bar and to extend beyond the Solar orbit into the outer Galaxy. Carbon monoxide (CO) emission from molecular clouds is a bright star formation tracer that was recently discovered in the OSC in the first Galactic quadrant and may extend into the second quadrant. The population of star formation tracers in the OSC remains largely uncharacterized in part because the arm is distant enough from the Galactic Center to be affected by the Galactic warp. The OSC rises above the Galactic plane by nearly 4 degrees in the first quadrant, meaning most in-plane surveys of molecular gas or star formation tracers have missed the arm previously. Here we use the Arizona Radio Observatory (ARO) 12m telescope to observe 12CO J = 1-0 and 13CO J = 1-0 transitions toward 158 HII region candidates in the first and second Galactic quadrants chosen from the WISE Catalog of Galactic HII Regions. These targets are spatially coincident with the Galactic longitude-latitude (l, b) OSC locus as defined by HI emission. We detect CO toward most of our targets, many of which have at least one emission line originating beyond the Solar orbit. We compare the physical properties of molecular clouds in the OSC to the physical properties of molecular clouds located elsewhere in the Galaxy.