JPL Home NASA Home Caltech Home
Follow this link to skip to the main content
NASA Logo - Jet Propulsion Laboratory
JPL Home Earth Solar System Stars & Galaxies Technology
Science Visitor and Colloquium Program
SVCP Home
Meetings
Information for Visitors
Contact
Restricted
 
Special Exoplanet Science Seminar

Constraining Methane Abundance and Cloud Properties from the Reflected Light Spectra of Directly Imaged Exoplanets
Presented by Roxana Lupu
NASA Ames Research Center

Wednesday, April 25, 2018
12:00 noon in 169-336

Abstract
We have assembled an atmospheric retrieval package for the reflected light spectra of gas- and ice- giants in order to inform the design and estimate the scientific return of future space-based coronagraph instruments. Such instruments will have a working bandpass of ~0.4-1 microns and a resolving power R~70, and will enable the characterization of tens of exoplanets in the Solar neighborhood. The targets will be chosen form known RV giants, with estimated effective temperatures of ~100-600 K and masses between 0.3 and 20 M_Jupiter. In this regime, both methane and clouds will have the largest effects on the observed spectra. Our retrieval code is the first to include cloud properties in the core set of parameters, along with methane abundance and surface gravity. We consider three possible cloud structure scenarios, with 0, 1 or 2 cloud layers, respectively. The best-fit parameters for a given model are determined using either a Monte Carlo Markov Chain ensemble sampler, or nested sampling. The most favored cloud structure is chosen by calculating the Bayes factors between different models. We present the performance of our retrieval technique applied to a set of representative model spectra, covering a SNR range form 5 to 20 and including possible noise correlations over a 25 or 100 nanometer scale. We are currently employing these tools to help define the technology requirements for the coronagraph instrument onboard WFIRST. I will briefly review our results regarding the science return as a function of instrument performance (bandpass, resolving power, SNR).

JPL Contact: If you would like to meet with the speaker, please contact Mark Swain.


SVCP Astrophysics


Privacy / Copyrights
  NASA Home Page
Site Manager:
Webmaster:

CL 08-3220