2009 Annual Science Report
VPL at University of Washington Reporting | JUL 2008 – AUG 2009
Astronomical Observations of Planetary Atmospheres and Exoplanets
This task focuses on what we can learn about planets in our Solar System and exoplanets using astronomical remote-sensing techniques. These techniques include radial velocity, secondary eclipse and, for planets in our own Solar System, direct spectroscopy. These astronomical observations both tell us more about the universe, and allow us to test retrieval and observing techniques that may one day be used on extrasolar terrestrial planets.
This year we continued astronomical observations of planets in our own Solar System (Neptune and Venus) and also observed and characterized extrasolar planets. These studies allow us to not only improve our understanding of these astronomical bodies, but in most cases also serve as explorations and tests of retrieval and observing techniques that may one day be used on extrasolar terrestrial planets.
Solar System Planets
We published a comparison of existing water vapor line lists for modeling the Venus atmosphere. This systematic test allowed us to determine which line list best simulated near-infrared spectroscopic observations of the Venus lower atmosphere, and led to the realization that previous line lists had resulted in an overestimated of the amount of water vapor in the lower atmosphere (Bailey, 2009). This result therefore also has consequences for our understanding of the efficiency of the Venus greenhouse mechanism.
We also completed and published ground-based observations of the Venus lower atmosphere (Bailey et al., 2008a) and the O2 airglow from the Venus mesosphere. We used the vibration-rotation structure of the 1.27um O2 singlet-delta emission to determine atmospheric temperatures at the emitting levels. A comparison of these temperatures with data obtained from the Venus Express spacecraft showed good agreement within measurement errors (Bailey et al., 2008b)
We also published detection and quantification of new hydrocarbons in Neptune’s atmosphere, as seen in spectra taken using the Spitzer Space telescope (Meadows et al., 2008). The new hydrocarbons help to constrain models of organic chemistry in the Neptune atmosphere.
We published the first spectrum of an extrasolar Jovian planet to show a definitive detection of water vapor in the atmosphere be spectrally–resolving the shape of the 6.3um water band in Spitzer observations of HD189733b taken during secondary eclipse (Grillmair et al., 2008).
Other work on exoplanets included detection of a new planet via radial velocity measurements (Bailey et al., 2009) and a white paper on the need for more research in extrasolar planet molecular spectroscopy, in which several of our team members participated (Swain et al., 2009).