Molecular gas in irradiated protoplanetary discs

J S Greaves

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Gas discs around young stars typically disappear after a few Myr and it has been suggested that the discs are internally photoevaporated, but the stellar ultraviolet and X-ray radiation appears insufficient for this mechanism to work. Archival data are used to search for any relation between X-ray luminosity and gas in the disc (traced by (CO)-C-13 molecules) for isolated young stars in Taurus. A significant correlation is found in that more irradiation increases the amount of (CO)-C-13, rather than dispersing the disc. Since high dust masses and accretion rates do not boost the X-ray luminosities, feeding of the radiation by the disc can be ruled out. It is more plausible that energetic photons are releasing molecules that would otherwise be frozen onto dust grains. In this case, estimates of disc mass using a canonical CO:H-2 ratio are unrealistic. However, the mass released in CO molecules could contribute to building a belt of icy comets similar to the Sun's Kuiper Belt.

Original languageEnglish
Number of pages4
JournalMonthly Notices of the Royal Astronomical Society
Volume364
DOIs
Publication statusPublished - 21 Nov 2005

Keywords

  • circumstellar matter
  • planetary systems : formation
  • planetary systems : protoplanetary discs
  • T-TAURI STARS
  • MAIN-SEQUENCE STARS
  • YOUNG STELLAR OBJECTS
  • X-RAY-EMISSION
  • CIRCUMSTELLAR DISKS
  • GIANT PLANETS
  • CO EMISSION
  • IUE ATLAS
  • ACCRETION
  • PHOTOEVAPORATION

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