Exoclimes Group

The Exoplanets & Exoclimes Group is based at the University of Bern, Switzerland, and is supported by the Swiss National Science Foundation, the PlanetS NCCR and the MERAC Foundation.

Exoclimes Group posts

Paper on non-isothermal sodium diagnostics accepted by ApJL

Posted on: Fri, 03/20/2015 - 06:35 by: heng

Our paper on non-isothermal diagnostics for interpreting the sodium doublet lines detected in transiting exoplanets has been accepted by the Astrophysical Journal Letters (ApJL): Heng, Wyttenbach, Lavie, Sing, Ehrenreich & Lovis (2015). It provides easy-to-use analytical formulae for inferring temperatures and number densities and improves upon work by Fortney (2005) and Lecavelier des Etangs et al. (2008). http://arxiv.org/abs/1503.05582

EEG Journal Club : Atmospheric retrieval and C/O ratio

Posted on: Fri, 03/20/2015 - 06:36 by: lavie

During our weekly journal club we reviewed Line et al. (2014a, The Astrophysical Journal 783, 70). Using Bayesian inference, he retrieved molecules abundances and TP profile for nine exoplanets and analyze theirs C/O ratio. We discussed the importance of this ratio to trace the location of a planet (in regard of the different snow lines – H2O, CO2) during the accretion process. We also concluded that lack of numerous data points for exoplanets makes difficult to constrain the physical parameters in the retrieval and doesn’t allow to make a strong statement (for example solar C/O falls within the 68% confidence interval for 8 planets).
Finally, we also discussed about Line et al. (2014b, The Astrophysical Journal 793, 33) where the same author applied the retrieval scheme to Brown Dwarf. As we have a lot more observations points for those objects, the retrieved parameters are better constrained and one can start addressing physical issues such as compositional differences between Brown Dwarf.

PLATO mission workshop on exoplanetary atmospheres

Posted on: Sun, 03/01/2015 - 20:38 by: heng

Kevin Heng is attending the workshop on "Atmospheric science in the context of CHEOPS, TESS, K2 and PLATO" at the DLR (German Aerospace Agency) in Berlin, from 2-4 March 2015, as part of the scientific organising committee. Daniel Kitzmann is also attending. Guests include Zach Berta (MIT) representing TESS.

NASA Chief Scientist visits

Posted on: Wed, 02/25/2015 - 07:59 by: heng

Ellen Stofan, Chief Scientist for NASA, visited the University of Bern and delivered a seminar on NASA's vision for the planetary and exoplanetary sciences.

Kurt Hanselmann visits

Posted on: Wed, 02/25/2015 - 07:58 by: heng

Kurt Hanselmann visited from ETH Zurich's Climate Geology department and gave a CSH Colloquium reviewing planetary geomicrobiology and arguing for why astrobiology should be revived as an experimental space science.

Hydrogen-imaging paper on Supernova 1987A accepted by ApJ Letters

Posted on: Tue, 02/17/2015 - 08:04 by: heng

A paper on using the Balmer-alpha and Lyman-alpha lines of hydrogen, recorded using the Hubble Space Telescope, to image the remnant of Supernova 1987A has just been accepted by the Astrophysical Journal Letters (ApJL): France et al. (2015). Kevin was involved as a secondary co-author and part of the SAINTS (Supernova 1987A Intensive Survey) team. The France et al. analysis solves the mystery of the over-abundance of Lyman-alpha photons relative to Balmer-alpha ones (e.g., see Heng & McCray 2007): they are simply produced by the X-ray heating of the outer debris. The preprint is available in the Papers section of the website.

Bayesian inversion technique for interiors of rocky exoplanets

Posted on: Tue, 02/17/2015 - 07:54 by: heng

Caro just had a paper accepted by Astronomy & Astrophysics (A&A) on using a Bayesian inversion technique, trained on data of Earth and Solar System bodies, to infer the interior structure and composition of rocky exoplanets: http://lanl.arxiv.org/abs/1502.03605. Congrats, Caro!

Maria Oreshenko starts

Posted on: Thu, 02/12/2015 - 19:22 by: heng

Maria Oreshenko started as a Masters student in the Exoplanets & Exoclimes Group, working on 3D climate models with simplified radiative transfer and scattering. She will earn her Masters degree (Physics) from ETH Zurich, but pursue research at the University of Bern.

EEG Journal Club: chemical kinetics

Posted on: Thu, 02/12/2015 - 19:13 by: heng

In our EEG Journal Club, we discussed the methods of Nguyen et al. (2009, Atmospheric Environment, 43, 6287), who devised a way to optimise chemical kinetics networks by sorting them into fast and slow reactions.

Visit and Seminar by Nader Haghighipour (Hawaii)

Posted on: Thu, 02/12/2015 - 16:31 by: heng

Prof. Nader Haghighipour, who is from the University of Hawaii and is on sabbatical in Heidelberg, visited the University of Bern and delivered a seminar on the formation of the Solar System and an update on the "Mars is too big" problem encountered in numerical simulations.