Orion Proplyds

It is difficult to probe disk structure in regions beyond the most nearby dark clouds. Nonetheless, significant progress has been made with SMA observations of the proplyds in Orion (distance 400 pc), circumstellar disks that were first seen by the Hubble Space Telescope silhouetted against the bright background of the Orion Nebula and also photoionized by the O stars at the cluster center. As the disks are completely opaque in the optical and infrared, only lower limits to their masses could be obtained. At longer millimeter wavelengths, however, the free-free emission from the compact ionized flows dominated. The combination of high frequency, high resolution, and high sensitivity that the SMA affords enabled the first mass measurement of these disks. This work led to a 3-year survey of the Trapezium Cluster with detections of 28 (out of 55) disks, enough for a statistical comparison with the mass distribution in nearby dark clouds (Williams et al. 2005; Mann & Williams 2009a,b). The distributions are similar but the Trapezium Cluster lacks massive disks. The fraction of disks that contain a minimum mass solar nebula within 60 AU radius is estimated to be 10 to 15% in all three regions, which suggests the potential for forming Solar Systems is not compromised by the proximity to massive stars.

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Figure 5: At left is an SMA image of the 880 µm continuum emission from an optical binary system in the Orion Nebula, which allowed the masses of both protoplanetary disks to be determined. At right is the HST discovery image from Smith et al. (2005). The SMA image combines data taken in both compact and extended configurations. Contours begin at 3σ, where -2mJy is the rms noise level in the map, with each step representing a factor of 1.5 in intensity. This is a unique observation of a binary in which both stars have a substantial reservoir of raw, planet-building material: each disk is individually massive enough (0.07M⊙, 0.02M⊙) to potentially form a solar system. Disk 253-1536a is more massive than any previously observed Orion disk (Mann & Williams, 2009).

References:

S. M. Andrews, J. P. Williams, High Resolution Submillimeter Constraints on Circumstellar Disk Structure, 2007, ApJ, 659, 705

S. M. Andrews, D. J. Wilner, A. M. Hughes, C. Qi, C. P. Dullemond, Protoplanetary Disk Structures in Ophiuchus, 2009, ApJ, 700, 1502

A. M. Hughes, D. J. Wilner, I. Kamp, M. R. Hogerheijde, A Resolved Molecular Gas Disk around the Nearby A Star 49 Ceti, 2008, ApJ, 681, 626

A. M. Hughes, D. J. Wilner, J. Cho, D. P. Marrone, A. Lazarian, S. M. Andrews, R. Rao, Stringent Limits on the Polarized Submillimeter Emission from Protoplanetary Disks, 2009, ApJ, 704, 1204

R. K. Mann, J. P. Williams, The Circumstellar Disk Mass Distribution in the Orion Trapezium Cluster, 2009, ApJ, 694, L36

R. K. Mann, J. P. Williams, Massive Protoplanetary Disks in Orion Beyond the Trapezium Cluster, 2009, ApJ, 699, L55

K. I. Oberg, C. Qi, J.K.J. Fogel, E. A. Bergin, S. M. Andrews, C. Espaillat, T. A. van Kempen, D. J. Wilner, Disk Imaging Survey of Chemistry with SMA (DISCS): I. Taurus Protoplanetary Disk Data, 2010, accepted to ApJ

O. Panic, M. R. Hogerheijde, D. Wilner, C. Qi, A break in the gas and dust surface density of the disc around the T Tauri star IM Lup, 2009, A&A, 501, 269

C. Qi, P. T. P. Ho, D. J. Wilner, S. Takakuwa, N. Hirano, N. Ohashi, T. L. Bourke, Q. Zhang, G. A. Blake, M. Hogerheijde, M. Saito, M. Choi, and J. Yang, Imaging the Disk around TW Hydrae with the Submillimeter Array, 2004, ApJ, 616, L11

C. Qi, D. J. Wilner, N. Calvet, T. L. Bourke, G. A. Blake, M. R. Hogerheijde, P. T. P. Ho, and E. Bergin, CO J=6--5 Observations of TW Hya with the SMA, 2006, ApJ, 636, L157

C. Qi, D.J. Wilner, Y. Aikawa, G.A. Blake, M.R. Hogerheijde, Resolving the chemistry in the disk of TW Hydrae I. Deuterated species, 2008, ApJ, 681, 1396

A. Raman, M. Lisanti, D.J. Wilner, C. Qi, M. Hogerheijde, A Keplerian Disk around the Herbig Ae star HD169142, 2006, AJ, 131, 2290

J. P. Williams, S. M. Andrews, and D. J. Wilner, The Masses of the Orion Proplyds from Submillimeter Dust Emission , 2005, ApJ, 634, 495

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SMA Research: Circumstellar Disks

SMA Research