Thermodynamics of giant planet formation: shocking hot surfaces on circumplanetary discs

Szulágyi, J.; Mordasini, Christoph (2017). Thermodynamics of giant planet formation: shocking hot surfaces on circumplanetary discs. Monthly notices of the Royal Astronomical Society - letters, 465(1), L64-L68. Oxford University Press 10.1093/mnrasl/slw212

Text slw212.pdf - Published Version Restricted to registered users only Available under License Publisher holds Copyright. Download (1MB) | Request a copy

The luminosity of young giant planets can inform about their formation and accretion history. The directly imaged planets detected so far are consistent with the ‘hot-start’ scenario of high entropy and luminosity. If nebular gas passes through a shock front before being accreted into a protoplanet, the entropy can be substantially altered. To investigate this, we present high-resolution, three-dimensional radiative hydrodynamic simulations of accreting giant planets. The accreted gas is found to fall with supersonic speed in the gap from the circumstellar disc's upper layers on to the surface of the circumplanetary disc and polar region of the protoplanet. There it shocks, creating an extended hot supercritical shock surface. This shock front is optically thick; therefore, it can conceal the planet's intrinsic luminosity beneath. The gas in the vertical influx has high entropy which when passing through the shock front decreases significantly while the gas becomes part of the disc and protoplanet. This shows that circumplanetary discs play a key role in regulating a planet's thermodynamic state. Our simulations furthermore indicate that around the shock surface extended regions of atomic – sometimes ionized – hydrogen develop. Therefore, circumplanetary disc shock surfaces could influence significantly the observational appearance of forming gas giants.

Interest & Impact

Downloads

1 since deposited on 30 Jun 2017
0 in the past 12 months

Citations

5 Citations in Web of Science ®
6 Citations in Scopus

Search

in Google Scholar™

Services

Actions (login required)

Edit item

Actions (login required)

Edit item