Observability of giant planets during the final stage of their formation

• Applicants: Professor Dr. H. Hubertus Klahr; Professor Dr. Sebastian Wolf
• Subject Area: Astrophysics and Astronomy
• Term: from 2011 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 191707420

• Final Report Year: 2016

Final Report Abstract

Circumstellar disks are expected to be the birthplace of planetary systems. They predominantly consist of gas, with about 1% dust, and they are a byproduct of star formation. Since its inauguration, Atacama Large Millimeter/Submillimeter Array (ALMA) has revealed, that these objects are highly dynamical and show large scale structures in their distribution of matter. Meanwhile, several interactions have been proposed to create these structures. We explored the feasibility to observe large-scale structures predicted from theoretical investigation of circumstellar disk models. For this purpose, we applied following three-step process: First, the interaction processes were investigated in hydrodynamical simulations of the disk density profiles. Second, follow–up radiative transport calculations were performed on the basis of the above disk profiles. Finally, the observability was investigated for selected instrument. Following the above strategy, we investigated characteristic large scale disk structures resulting from planet–disk, binary–disk and magnetic–field–disk interactions. Motivated by the availability of the ALMA, the main focus was on feasibility studies of observations in the (sub)mm wavelength range. We found that ALMA is able to observe the characteristic structures of each considered interaction process, but these could appear very similar although the origin is different. Within the parameter space and wavelength range considered, magnetic–field–disk and planet–disk interaction can only be distinguished on the basis of the direct radiation of the planetary source. The conditions under which it is possible to detect the planetary radiation are investigated along with the question about what one can learn from a measurement of the planetary radiation about the properties of the planet itself. In addition, the decoupling of the motion of sufficiently large dust particles from that of the gas was explored, which leads to a distribution of these particles totally different from the distribution of the gas molecules in the disk. These large dust particles dominate the thermal continuum emission of a circumstellar disk in the (sub)mm range. Thus, structures in the distribution of large particles are particularly straight-forward to be observed with ALMA. Our model shows a qualitative similarity to the recent ALMA observation of HL Tau. In summary, we found that ALMA – but also other high-angular resolution, highly sensitive telescopes/instruments which go into operation currently or in the near future, but at different wavelength ranges – will allow us to trace the various large-scale disk structures induced by planets, binaries, and the magnetic field–disk interaction. However, a further important result of our studies is that there exist various ambiguities in the observed structures of different physical origin. Future studies are necessary to resolve these ambiguities, e.g., through dedicated multi-wavelength observations.

Publications

• “DoAr 33: a good candidate for revealing dust growth and settling in protoplanetary disks”, Astronomy and Astrophysics, 546, A7 (2012)
  Y. Liu, D. Madlener, S. Wolf, H. Wang, and J.P. Ruge
  
• “Accretion of Gas onto Gap-opening Planets and Circumplanetary Flow Structure in Magnetized Turbulent Disks.”, The Astrophysical Journal 769, 97 (2013)
  Uribe, A. L., Klahr, H., and Henning, T.
  
• “Tracing large-scale structures in circumstellar disks with ALMA”, Astronomy and Astrophysics, 549, A97 (2013)
  J.P. Ruge, S. Wolf, A. Uribe, and H.H. Klahr
  
• “Tracing Planets in Circumstellar Discs”, EPJ Web of Conferences Volume 46, 2013
  J.P. Ruge, S. Wolf, A. Uribe, H.H. Klahr
  
• “Image reconstruction with MATISSE at the VLTI ”, Proc. SPIE 9146, Optical and Infrared Interferometry IV, 91461 (2014)
  R. Köhler, J.P. Ruge, J.-U. Pott, S. Wolf, W. Jaffe, and Th. Henning
  
• “Planet-induced disk structures: A comparison between (sub)mm and infrared radiation”, Astronomy and Astrophysics, 572, L2 (2014)
  J.P. Ruge, S. Wolf, A. Uribe, and H.H. Klahr
  
• “Gaps, rings, and non-axisymmetric structures in protoplanetary disks - From simulations to ALMA observations”, Astronomy and Astrophysics, 574, A68 (2015)
  M. Flock, J.P. Ruge, N. Dzyurkevich, Th. Henning, H.H. Klahr, and S. Wolf
  
• “Structures in circumbinary disks: Prospects for observability”, Astronomy and Astrophysics, 579, A110 (2015)
  J.P. Ruge, S. Wolf, T. Demidova, and V. Grinin
  
• “Tracing planet-induced structures in circumstellar disks using molecular lines”, Astronomy and Astrophysics, 579, A105 (2015)
  F. Ober, S. Wolf, A.L. Uribe, and H.H. Klahr
  
• “Vortex Formation and Evolution in Planet Harboring Disks Under Thermal Relaxation” The Astrophysical Journal 810, 94 (2015)
  A. Lobo Gomes, H. Klahr, A. L. Uribe, P. Pinilla, and C. Surville