Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session 11HE: Physics of Planetary Interiors |
Hide Abstracts |
Sponsoring Units: HEDP HEDLA Chair: Jonathan Fortney, University of California, Santa Cruz Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), Promenade F |
Sunday, April 13, 2008 3:10PM - 3:35PM |
11HE.00001: Super Earths: The Structure of Massive Terrestrial Planets Invited Speaker: Super-Earths are the newest class of extra-solar planets with a mass range between 1-10 $M_{\oplus}$. We investigate the composition and structure of these planets. With their larger masses, they experience very large internal pressures. We find that the central pressure scales proportionately with mass, reaching values that challenge the understanding of rock behavior under such extreme conditions. Pressure also constraints the power law relationship between mass and radius of solid planets. The value for the exponent is 0.262 for super-Earths and 0.3 for planets between 5-50\% $M_{\oplus}$. Despite uncertainties in the equation of state, composition and temperature structure, the mass-radius relationship is robust. Therefore, it is useful for inferring the expected signal in transit searches. In the next few years many super-Earths will be discovered and their masses and radius will be available. We find that there is a large degeneracy in composition that can fit an average density measurement. [Preview Abstract] |
Sunday, April 13, 2008 3:35PM - 4:00PM |
11HE.00002: Reproducing planetary cores in the laboratory Invited Speaker: This abstract not available. [Preview Abstract] |
Sunday, April 13, 2008 4:00PM - 4:25PM |
11HE.00003: First Principles Calculations of Hydrogen-Helium Mixtures and the Structure of Jupiter Invited Speaker: Most of the over two hundred recently discovered extrasolar planets are gas giants that are primarily composed of dense fluid hydrogen and helium at megabar pressures and temperature of thousands of degrees Kelvin. The characterization of hydrogen-helium mixtures at such extreme conditions has posed a challenge to experimental and theoretical methods. Great progress has been made with recent shock wave experiments and the megabar regime has been probed. However, the temperatures were much higher and the densities were significantly lower than those present in giant planets because planetary interiors are characterized by isentropes, which rise much slower in the P-T plane than shock Hugoniot curves. In this talk, results from an extensive set of density-functional molecular dynamics simulations will be presented [J. Vorberger \textit{et al.,} \textit{Phys. Rev. B} \textbf{75} (2006) 024206] and an equation of state (EOS) of hydrogen-helium mixtures that spans for Jupiter's interior is derived. Going beyond the commonly assumed linear mixing approximation, the interaction effects of dense hydrogen and helium are analyzed. It will be discussed how helium affects the molecular-to-metallic transition in hydrogen and why the presence of helium stabilizes the molecular phase. Based on this first-principles EOS, an updated model for the interior of Jupiter will be introduced. Our interior model updates the suite of models that were based on the widely used Saumon-Chabrier-Van Horn (SCVH) EOS. Deviations from SCVH are up to about 5 percent depending on the pressure, and thus affect interior models at the same level. Unlike SCVH, the computed DFT-EOS does not predict any first-order thermodynamic discontinuities associated with pressure-dissociation and metallization of hydrogen. Finally, the size of a rocky core in Jupiter and the heavy elements enrichment in its mantle will be estimated. It will be descussed whether the planet was form by core-accretion. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700