NOAO >   Observing Info >   Approved Programs >   2017A-0223

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Program Information for 2017A-0223


PI: William Armentrout, West Virginia University, wparmentrout@mix.wvu.edu
Address: Department of Physics and Astronomy, White Hall, 135 Willey Street, Morgantown, WV, 26505 United States

CoI: Loren Anderson, West Virginia University
CoI: Morten Andersen, Gemini Observatory

Title: High-Mass Star Formation in the Outer Scutum-Centaurus Arm

Abstract: The Outer Scutum-Centaurus (OSC) arm is the most distant spiral arm in the Milky Way, but until recently little was known about this structure. Discovered by Dame and Thaddeus (2011), the OSC lies ~15 kpc from the Galactic center and appears ~4 deg. above the Galactic mid-plane in the first quadrant due to the Galactic warp, leaving it unsampled by most Galactic plane surveys. We are trying to understand distant star formation in the far outer Galaxy by studying HII regions in the OSC. Such confirmations require spectroscopic observations to determine radial velocities. Due to their distances, radio spectroscopic observations are difficult. The warp of this arm above the Galactic plane means that optical observations of distant HII regions are a possibility. Our group has increased the number of detected HII regions within the OSC to 12 from just one previously. We propose here to use the GMOS-North long-slit spectrometer to observe the 656 nm H-Alpha line of 42 HII region candidates coincident with the OSC. All proposed targets have radio continuum and mid-infrared detections, meaning they are very likely HII regions. H-Alpha detections would allow us to confirm their classifications and assign kinematic distances, determining their position in the Galaxy. Six minute integrations would give ~15 sigma detections of the faintest expected HII regions, even in poor weather. Population synthesis modeling indicates that our survey of high-mass star formation is nearly complete to the edge of the Galaxy in the first Galactic quadrant; these sources are the final piece.

Program Type: Standard/Galactic

Scheduled Nights:
Run 1 (2017A):  GEM-NQ/GMOSN -- 16.8hrs band 3 (GN-2017A-Q-80)


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NOAO >   Observing Info >   Approved Programs >   2017A-0223

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