Rappaport, Saul and Sanchis-Ojeda, Roberto and Rogers, Leslie A. and Levine, Alan and Winn, Joshua N. (2013) The Roche Limit for Close-orbiting Planets: Minimum Density, Composition Constraints, and Application to the 4.2 hr Planet KOI 1843.03. Astrophysical Journal Letters, 773 (1). Art. No. L15. ISSN 0004-637X. http://resolver.caltech.edu/CaltechAUTHORS:20130903-093151626
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The requirement that a planet must orbit outside of its Roche limit gives a lower limit on the planet's mean density. The minimum density depends almost entirely on the orbital period and is immune to systematic errors in the stellar properties. We consider the implications of this density constraint for the newly identified class of small planets with periods shorter than half a day. When the planet's radius is accurately known, this lower limit to the density can be used to restrict the possible combinations of iron and rock within the planet. Applied to KOI 1843.03, a 0.6 R⊕ planet with the shortest known orbital period of 4.245 hr, the planet's mean density must be ≳7 g cm^(–3). By modeling the planetary interior subject to this constraint, we find that the composition of the planet must be mostly iron, with at most a modest fraction of silicates (≾30% by mass).
|Additional Information:||© 2013 The American Astronomical Society. Received 2013 June 3; accepted 2013 July 12; published 2013 July 29. We thank Eugene Chiang for helpful discussions and Dimitar Sasselov for timely correspondence about mantle-stripping models. We are grateful to the Kepler team for providing such valuable data to the community. L.A.R. acknowledges NASA support through the Hubble Fellowship grant #HF-51313.01- A. R.S.O. and J.N.W. acknowledge NASA support through the Kepler Participating Scientist Program. This research has made use of the NASA Exoplanet Archive, and the Mikulski Archive for Space Telescopes (MAST).|
|Subject Keywords:||instabilities; planetary systems; planets and satellites: detection; planets and satellites: individual (KOI 1843)|
|Official Citation:||The Roche Limit for Close-orbiting Planets: Minimum Density, Composition Constraints, and Application to the 4.2 hr Planet KOI 1843.03 Saul Rappaport et al. 2013 ApJ 773 L15|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||18 Sep 2013 00:06|
|Last Modified:||18 Sep 2013 00:06|
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