A precise estimate of the radius of HD 149026b

Philip Nutzman, David Charbonneau, Joshua N. Winn, Heather A. Knutson, Jonathan J. Fortney, Matthew J. Holman, Eric Agol

Research output: Contribution to journalArticle


We present Spitzer 8 μm transit observations of the extrasolar planet system HD 149026b. At this wavelength, transit light curves are weakly affected by stellar limb-darkening, allowing for a simpler and more accurate determination of planetary parameters. We measure a planet-star radius ratio of Rp/R* = 0.05158±0.00077, and in combination with ground-based data and independent constraints on the stellar mass and radius, we derive an orbital inclination of i = 85°.4 +0°.9-0°.8 and a planet radius of 0.755 ± 0.040 RJ. These measurements further support models in which the planet is greatly enriched in heavy elements.

Original languageEnglish (US)
Pages (from-to)466-469
Number of pages4
JournalProceedings of the International Astronomical Union
Issue numberS253
StatePublished - May 2008

All Science Journal Classification (ASJC) codes

  • Medicine (miscellaneous)
  • Astronomy and Astrophysics
  • Nutrition and Dietetics
  • Public Health, Environmental and Occupational Health
  • Space and Planetary Science

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    Nutzman, P., Charbonneau, D., Winn, J. N., Knutson, H. A., Fortney, J. J., Holman, M. J., & Agol, E. (2008). A precise estimate of the radius of HD 149026b. Proceedings of the International Astronomical Union, 4(S253), 466-469. https://doi.org/10.1017/S1743921308026951