Four sub-Saturns with dissimilar densities: windows into planetary cores and envelopes
Article
Article Title | Four sub-Saturns with dissimilar densities: windows into planetary cores and envelopes |
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ERA Journal ID | 1048 |
Article Category | Article |
Authors | Petigura, Erik A. (Author), Sinukoff, Evan (Author), Lopez, Eric D. (Author), Crossfield, Ian J. M. (Author), Howard, Andrew W. (Author), Brewer, John M. (Author), Fulton, Benjamin J. (Author), Isaacson, Howard T. (Author), Ciardi, David R. (Author), Howell, Steve B. (Author), Everett, Mark E. (Author), Horch, Elliott P. (Author), Hirsch, Lea A. (Author), Weiss, Lauren M. (Author) and Schlieder, Joshua E. (Author) |
Journal Title | The Astronomical Journal |
Journal Citation | 153 (4) |
Article Number | 142 |
Number of Pages | 19 |
Year | 2017 |
Publisher | IOP Publishing |
Place of Publication | United States |
ISSN | 0004-6256 |
1538-3881 | |
Digital Object Identifier (DOI) | https://doi.org/10.3847/1538-3881/aa5ea5 |
Web Address (URL) | https://iopscience.iop.org/article/10.3847/1538-3881/aa5ea5 |
Abstract | We present results from a Keck/HIRES radial velocity campaign to study four sub-Saturn-sized planets, K2-27b, K2-32b, K2-39b, and K2-108b, with the goal of understanding their masses, orbits, and heavy-element enrichment. The planets have similar sizes (RP=4.5-5.5 ), but have dissimilar masses (MP=16-60 ), implying a diversity in their core and envelope masses. K2-32b is the least massive (MP = 16.5 ± 2.7 M) and orbits in close proximity to two sub-Neptunes near a 3:2:1 period commensurability. K2-27b and K2-39b are significantly more massive at MP = 30.9 ± 4.6 M and MP = 39.8 ± 4.4 M, respectively, and show no signs of additional planets. K2-108b is the most massive at MP = 59.4 ± 4.4 M, implying a large reservoir of heavy elements of about ≈50 . Sub-Saturns as a population have a large diversity in planet mass at a given size. They exhibit remarkably little correlation between mass and size; sub-Saturns range from ≈6-60 M, regardless of size. We find a strong correlation between planet mass and host star metallicity, suggesting that metal-rich disks form more massive planet cores. The most massive sub-Saturns tend to lack detected companions and have moderately eccentric orbits, perhaps as a result of a previous epoch of dynamical instability. Finally, we observe only a weak correlation between the planet envelope fraction and present-day equilibrium temperature, suggesting that photo-evaporation does not play a dominant role in determining the amount of gas sub-Saturns accrete from their protoplanetary disks. |
Keywords | planets and satellites; composition; planets and satellites; detection; dynamical evolution and stability |
Contains Sensitive Content | Does not contain sensitive content |
ANZSRC Field of Research 2020 | 510109. Stellar astronomy and planetary systems |
Public Notes | For access to this article, please click on the URL link provided. |
Byline Affiliations | California Institute of Technology (Caltech), United States |
University of Hawaii, United States | |
University of Edinburgh, United Kingdom | |
University of California, United States | |
Yale University, United States | |
National Aeronautics and Space Administration (NASA), United States | |
National Optical Astronomy Observatory, United States | |
Southern Connecticut State University, United States | |
University of Montreal, Canada | |
Institution of Origin | University of Southern Queensland |
https://research.usq.edu.au/item/q4347/four-sub-saturns-with-dissimilar-densities-windows-into-planetary-cores-and-envelopes
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