SMA Research: Hallmarks of Ongoing Planet Formation in Circumstellar Disks

The 880 micron dust continuum radiation from the protoplanetary "transition" disk around the young star LkCa 15 has been imaged in fine detail (an angular resolution of about 0.3 arcsec, or 40 AU) with the SMA, taking advantage of its 0.5 km-long baselines in the "very extended" configuration. Transition disks like those around LkCa 15 exhibit strange dips in their mid-infrared spectra, which are thought to reflect a deficit of warm dust in the disk regions located close to the central stellar radiation source. However, models of these spectra provide only limited (and model-dependent) constraints on the sizes of these disk clearings, and do not rule out alternative explanations. Direct high-resolution images with the SMA have now confirmed the presence of large "cavities" in these transition disks, on scales comparable to the extent of our Solar System (20-70 AU in radius). These studies have spurred a great deal of theoretical work to explain the cavities, with the leading candidate being dynamical interactions with one or more low-mass (presumably planetary) companions during their formation epoch. In the particular case of LkCa 15, these observations spurred a recent infrared search for a potential companion with the Keck telescope: Kraus & Ireland (2012) report the presence of LkCa 15b inside the dust disk cavity, the youngest (~1-3 Myr) giant planet currently known.

Science Publications

  • Sean Andrews (Harvard-Smithsonian CfA), et al.
    Resolved Images of Large Cavities in Protoplanetary Transition Disks, 2011, ApJ, 732, 42 (ADS)
  • Sean Andrews (Harvard-Smithsonian CfA), et al.
    A Closer Look at the LkCa 15 Protoplanetary Disk, 2011, ApJ, 742, L5 (ADS)
  • J.M. Brown (Max-Planck-Institut für extraterrestrische Physik, Garching bei München, Germay), et al.
    Evidence for Dust Clearing Through Resolved Submillimeter Imaging, 2009, ApJ, 704, 496 (ADS)
  • Meredith A. Hughes (Harvard-Smithsonian CfA), et al.
    A Spatially Resolved Inner Hole in the Disk Around GM Aurigae, 2009, ApJ, 698, 131H (ADS)
  • Adam L. Kraus (Institute for Astronomy, University of Hawaii), et al.
    LkCa 15: A Young Exoplanet Caught at Formation?, 2012, ApJ, 745, 5K (ADS)
  •   LkCa 15

    Sean Andrews, 2011