Now showing items 1-10 of 10

    • Chemical Imaging of the CO Snow Line in the HD 163296 Disk 

      Qi, Chunhua; Oberg, Karin; Andrews, Sean M.; Wilner, David J.; Bergin, Edwin A.; Hughes, Amy L; Hogherheijde, Michiel; D’Alessio, Paola (IOP Publishing, 2015)
      The condensation fronts (snow lines) of H2O, CO, and other abundant volatiles in the midplane of a protoplanetary disk affect several aspects of planet formation. Locating the CO snow line, where the CO gas column density ...
    • The comet-like composition of a protoplanetary disk as revealed by complex cyanides 

      Oberg, Karin; Guzmán, Viviana V.; Furuya, Kenji; Qi, Chunhua; Aikawa, Yuri; Andrews, Sean M.; Loomis, Ryan; Wilner, David J. (Nature Publishing Group, 2015)
      Observations of comets and asteroids show that the Solar Nebula that spawned our planetary system was rich in water and organic molecules. Bombardment brought these organics to the young Earth's surface, seeding its early ...
    • Constraining the X-ray and cosmic ray ionization chemistry of the TW Hya protoplanetary disk: evidence for a sub-interstellar cosmic-ray rate. 

      Cleeves, Lauren Ilsedore; Bergin, Edwin A.; Qi, Chunhua; Adams, Fred C.; Oberg, Karin (IOP Publishing, 2015)
      We present an observational and theoretical study of the primary ionizing agents (cosmic rays and X-rays) in the TW Hya protoplanetary disk. We use a set of resolved and unresolved observations of molecular ions and other ...
    • Double DCO+ rings reveal CO ice desorption in the outer disk around IM Lup 

      Oberg, Karin; Furuya, Kenji; Loomis, Ryan; Aikawa, Yuri; Andrews, Sean M.; Qi, Chunhua; Dishoeck, Ewine F. van; Wilner, David J. (IOP Publishing, 2015)
      In a protoplanetary disk, a combination of thermal and non-thermal desorption processes regulate where volatiles are liberated from icy grain mantles into the gas phase. Non-thermal desorption should result in volatile-enriched ...
    • First Detection of c-C3H2 in a Circumstellar Disk 

      Qi, Chunhua; Oberg, Karin; Wilner, David J.; Rosenfeld, Katherine Ann (IOP Publishing, 2013)
      We report the first detection of c-C3H2 in a circumstellar disk. The c-C3H2 J = 6-5 line (217.882 GHz) is detected and imaged through Atacama Large Millimeter Array (ALMA) Science Verification observations toward the disk ...
    • H2CO and N2H+ in Protoplanetary Disks: Evidence for a CO-Ice Regulated Chemistry 

      Qi, Chunhua; Oberg, Karin; Wilner, David J. (IOP Publishing, 2013)
      We present Submillimeter Array observations of H2CO and N2H+ emission in the disks around the T Tauri star TW Hya and the Herbig Ae star HD 163296 at 2"-6" resolution and discuss the distribution of these species with ...
    • HNC in Protoplanetary Disks 

      Graninger, Dawn M; Oberg, Karin; Qi, Chunhua; Kastner, Joel (IOP Publishing, 2015)
      The distributions and abundances of small organics in protoplanetary disks are potentially powerful probes of disk physics and chemistry. HNC is a common probe of dense interstellar regions and the target of this study. ...
    • Imaging of the CO Snow Line in a Solar Nebula Analog 

      Qi, Chunhua; Oberg, Karin; Wilner, David J.; D'Alessio, Paola; Bergin, E.; Andrews, Sean M.; Blake, G. A.; Hogerheijde, M. R.; van Dishoeck, E. F. (American Association for the Advancement of Science (AAAS), 2013)
      Planets form in the disks around young stars. Their formation efficiency and composition are intimately linked to the protoplanetary disk locations of “snow lines” of abundant volatiles. We present chemical imaging of the ...
    • An Old Disk Still Capable of Forming a Planetary System 

      Bergin, Edwin A.; Cleeves, L. Ilsedore; Gorti, Uma; Zhang, Ke; Blake, Geoffrey A.; Green, Joel D.; Andrews, Sean M.; Evans II, Neal J.; Henning, Thomas; Oberg, Karin; Pontoppidan, Klaus; Qi, Chunhua; Salyk, Colette; van Dishoeck, Ewine F. (Nature Publishing Group, 2013)
      From the masses of the planets orbiting the Sun, and the abundance of elements relative to hydrogen, it is estimated that when the Solar System formed, the circumstellar disk must have had a minimum mass of around 0.01 ...
    • A Ring of C2H in the Molecular Disk Orbiting TW Hya 

      Kastner, Joel H.; Qi, Chunhua; Gorti, Uma; Hily-Blant, Pierre; Oberg, Karin; Forveille, Thierry; Andrews, Sean; Wilner, David J. (IOP Publishing, 2015)
      We have used the Submillimeter Array to image, at ~1farcs5 resolution, C2H $N=3\to 2$ emission from the circumstellar disk orbiting the nearby (D = 54 pc), ~8 Myr-old, ~0.8 ${{M}_{\odot }}$ classical T Tauri star TW Hya. ...