Journal
ASTRONOMICAL JOURNAL
Volume 154, Issue 6, Pages -Publisher
IOP PUBLISHING LTD
DOI: 10.3847/1538-3881/aa918b
Keywords
planets and satellites: composition; planets and satellites: detection; planets and satellites: dynamical evolution and stability; planets and satellites: fundamental parameters; planets and satellites: gaseous planets planets; and satellites: interiors
Categories
Funding
- NSF [DGE 1144152, DGE 1256260]
- California Institute of Technology/Jet Propulsion Laboratory - NASA
- TESS mission through Massachusetts Institute of Technology
- European Union Seventh Framework Programme [313014]
- NASA [NNX15AC90G, NNX17AB59G, NAS5-26555]
- John Templeton Foundation
- Swiss Space Office (SSO)
- Harvard University Origin of Life Initiative (HUOLI)
- Scottish Universities Physics Alliance (SUPA)
- University of Geneva
- Smithsonian Astrophysical Observatory (SAO)
- Italian National Astrophysical Institute (INAF)
- University of St. Andrews
- Queens University Belfast
- University of Edinburgh
- NASA
- National Science Foundation [ACI-1053575]
- National Science Foundation
- U.S. Department of Energy's Office of Science
- National Aeronautics and Space Administration
- NASA Science Mission directorate
- NASA Office of Space Science [NNX13AC07G]
- Science and Technology Facilities Council [ST/M001296/1] Funding Source: researchfish
- STFC [ST/M001296/1, ST/P000312/1] Funding Source: UKRI
Ask authors/readers for more resources
We present precise radial velocity observations of WASP-47, a star known to host a hot Jupiter, a distant Jovian companion, and, uniquely, two additional transiting planets in short-period orbits: a super-Earth in a approximate to 19 hr orbit, and a Neptune in a approximate to 9 day orbit. We analyze our observations from the HARPS-N spectrograph along with previously published data to measure the most precise planet masses yet for this system. When combined with new stellar parameters and reanalyzed transit photometry, our mass measurements place strong constraints on the compositions of the two small planets. We find that, unlike most other ultra-short-period planets, the inner planet, WASP-47 e, has a mass (6.83 +/- 0.66 M-circle plus) and a radius (1.810 +/- 0.027 R-circle plus) that are inconsistent with an Earth-like composition. Instead, WASP-47 e likely has a volatile-rich envelope surrounding an Earth-like core and mantle. We also perform a dynamical analysis to constrain the orbital inclination of WASP-47 c, the outer Jovian planet. This planet likely orbits close to the plane of the inner three planets, suggesting a quiet dynamical history for the system. Our dynamical constraints also imply that WASP-47 c is much more likely to transit than a geometric calculation would suggest. We calculate a transit probability for WASP-47 c of about 10%, more than an order of magnitude larger than the geometric transit probability of 0.6%.
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