skip to main content

SciTech ConnectSciTech Connect

Title: Shedding light on the eccentricity valley: Gap heating and eccentricity excitation of giant planets in protoplanetary disks

We show that the first order (non-co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the 'Eccentricity Valley' noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between ∼0.1 and ∼1 AU compared to metal-rich systems. We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius ∼0.1 AU, which is known to exist for several T Tauri systems. In the shadowed region between ∼0.1 and ∼1 AU, lack of gap insolation allows disk interactions to damp eccentricity. Outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets. We suggest that the self-shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.
Authors:
;  [1] ;  [2]
  1. Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada)
  2. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)
Publication Date:
OSTI Identifier:
22351407
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 782; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; DAMPING; DISTRIBUTION; DUSTS; ENTROPY; EXCITATION; HEATING; HYDRODYNAMICS; ILLUMINANCE; INTERACTIONS; METALLICITY; PLANETS; PROTOPLANETS; RESONANCE IONIZATION MASS SPECTROSCOPY; STARS; SUBLIMATION; VISIBLE RADIATION