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2010 Annual Science Report

VPL at University of Washington Reporting  |  SEP 2009 – AUG 2010

Astronomical Observations of Planetary Atmospheres and Exoplanets

Project Summary

This task encompasses remote-sensing observations of Solar System and extrasolar planets made by the VPL team. These observations, while providing scientific exploration in its own right, also allow us to test our planetary models and help advance techniques to retrieve information from the astronomical data that we obtain. This can include improving our understanding of the accuracy of inputs into our models, such as spectral databases. This year we made and/or analyzed observations of Venus and Titan taken by ground-based and spaceborne observatories, and improved models for extrasolar hot Jupiters.

4 Institutions
3 Teams
8 Publications
1 Field Site
Field Sites

Project Progress

During the reporting period we performed and/or analyzed observations of Venus and Titan and improved models for hot Jupiters and terrestrial exoplanets. Progress on these tasks are discussed in more detail below. Additionally, VPL international collaborator Jeremy Bailey is a member of the Anglo-Australian Telescope Rocky Planet Search team, which is conducting an intensive high-precisions radial velocity Doppler planet search. The AAT-RPS reported its first results this year, which put constraints on the fraction of stars with super-Earth planets (O’Toole et al., 2009). Bailey was also a co-I on two discovery papers for new, small, exoplanets. We also completed a review chapter on terrestrial planet atmospheres (Meadows and Seager, 2010) for the upcoming Exoplanets book.

Venus

We continue our observations of Venus using the Apache Point Observatory in New Mexico. New APO near-infrared spectral data to support the Venus Express (ESA) and Akutsaki (JAXA) missions will also be acquired this November. This data will be used to search for spatial variations in near-surface water abundance, signs of volcanic activity and the strength and morphology of the mesospheric O2 airglow on the Venus nightside. Work continues to model the abundance and distribution of CO and H2O in the lower Venus Atmosphere, with a paper in preparation.

Titan

We are near completion on analysis of Spitzer Infrared Spectrograph (IRS) observations of Titan. The data have been successfully fit using a combination of photochemical and radiative transfer modeling. A search for new hydrocarbons in this high S/N data is being prepared for publication.
In other work, we have improved the line list for methane at low temperatures, and have used it to model the atmosphere of Titan and the giant planets at near-infrared wavelengths (Bailey et al., 2010, submitted).

Planetary Model Improvements

The VSTAR radiative transfer model has been extended to cover high temperature objects such as hot Jupiters, brown dwarfs etc. by expanding the set of line lists (now 1.6 billion lines in total) and continuum processes modelled, and adding an equilibrium chemistry model (including gas phase chemistry, ionized species and condensate forming). Preliminary investigations into the inclusion of polarized radiative transfer into the VSTAR model have been completed, and we will attempt to implement this over the next few months. We have also made significant progress in installing a fast radiative transfer scheme into the VPL Climate model, which is being developed to model terrestrial planet atmospheres from Mars to super Earths.

Publications

  • Bailey, J., Ahlsved, L., & Meadows, V. S. (2011). The near-IR spectrum of Titan modeled with an improved methane line list. Icarus, 213(1), 218–232. doi:10.1016/j.icarus.2011.02.009

  • Jones, H. R. A., Butler, R. P., Tinney, C. G., O’Toole, S., Wittenmyer, R., Henry, G. W., … Jenkins, J. S. (2010). A long-period planet orbiting a nearby Sun-like star. Monthly Notices of the Royal Astronomical Society, 403(4), 1703–1713. doi:10.1111/j.1365-2966.2009.16232.x

  • O’Toole, S. J., Jones, H. R. A., Tinney, C. G., Butler, R. P., Marcy, G. W., Carter, B., … Wittenmyer, R. A. (2009). THE FREQUENCY OF LOW-MASS EXOPLANETS. The Astrophysical Journal, 701(2), 1732–1741. doi:10.1088/0004-637x/701/2/1732

  • Vogt, S. S., Wittenmyer, R. A., Butler, R. P., O’Toole, S., Henry, G. W., Rivera, E. J., … Batygin, K. (2009). A SUPER-EARTH AND TWO NEPTUNES ORBITING THE NEARBY SUN-LIKE STAR 61 VIRGINIS. The Astrophysical Journal, 708(2), 1366–1375. doi:10.1088/0004-637x/708/2/1366

  • Kasting, J.F.  (2010).  How to Find a Habitable Planet.  Princeton, NJ: Princeton University.
  • Kasting, J.F.  (In Press).  How to find a habitable planet.  Pathways Towards Habitable Planets.
  • Meadows, V.S. & Seager, S.  (2010).  Terrestrial Planet Atmospheres and Biosignatures.  In: Seager, S. (Eds.).  Exoplanets.  University of Arizona Press.
  • Sparks, W.B., Meadows, V., McCullough, P., Postman, M., Bussey, B. & Christian, C.  (2010).  Lunar Based Observations of the Earth as a Planet.