Chris and the Middle Kingdom Chris Ormel

Hubble Fellow
University of California, Berkeley

ormel AT astro DOT berkeley DOT edu

News Flashes

November 2014

Move to Amsterdam

Chris to start the research group "Origins of super-Earth" at the University of Amsterdam, the Netherlands

October 2014

Hydrodynamics of Planets' First Atmospheres

Small planets dominate the universe and even large planets were once small. As planets form in gas-rich disks a key question is how the planet's gravity shapes the gas around it, and in particular what the properties of the planet's primordial atmosphere are. In this study hydrodynamical simulations were conducted to solve for the flow pattern of the gas. Due to the gravity, the gas compresses close to the planet. This process is illustrated in the video to the right, where the white color indicates the density of the background gas (that of the circumstellar disk) and the red much higher densities. Naturally, the gas compresses near the surface of the planet, because the gravitational pull of the planet is strongest. ...

[More...] [ArXiv 1] [ArXiv 2]

Emergence of a steady 2D flow and a bound atmosphere around a planet embedded in the primordial, gas-rich disk

July 2014

Grain growth in protoplanetary atmospheres

Example of a calculation with the new structure equation for grain growth. The left panel shows the normalized temperature and density while the right panel plots the grain properties: their size, abundance, and opacity. Results of two simulations are presented: (i) grains only enter at the top of the atmosphere (solid lines); (ii) grains are additionally produced by ablating planetesimals within the atmosphere (dashed lines). In the latter grains coagulate quickly, but the bigger particles suppress the grain opacity. As a result, the temperature and density profiles are very similar.

Early atmospheres around planets — those still embedded in gaseous disks — are voluminous, but not necessarily very massive. How massive such atmosphere can become depends to a large extent on the thermodynamic properties of the atmospheric gas and its ability to cool.

This means that it depends on the opacity of the gas or rather the opacity of the grains within the gas....

[More...] [ADS] [ArXiv]

June 2014


Chris to attend the second ISSI (International Space Science Institute) meeting in Bern with world-leading experts to ponder planet formation issues.

[Meeting Link]

June 2014


Visiting (for the first time) the impressively-pretty and old city of Nice and the many good people at the Observatoire. Presenting our results on hydrodynamic flows past small planets, and, with Tristan Guillot, putting the finishing touches on our dust filtering paper.

May 2014

Vidi Innovational Research Incentive Scheme grant (NWO)

Chris has won a VIDI grant to set up a research group!

[Official announcement (NWO)] [NOVA announcement (Dutch)]

April 2014


Chris' second visit to Pasadena in two years, visiting Neal Turner, Rolf Kuiper, and Wladimir Lyra, among others