Li Zeng

A Detailed Model Grid for Solid Planets from 0.1 through 100 Earth Masses

This article describes a new grid for the mass-radius relation of three-layer exoplanets within the mass range of 0.1-100 M⊕. The three layers are: Fe (-phase of iron), MgSiO3 (including both the perovskite phase, post-perovskite phase, and its dissociation at ultrahigh pressures), and H2O (including Ices Ih, III, V, VI, VII, X, and the superionic phase along the melting curve). We discuss the current state of knowledge about the equations of state (EOS) that influence these calculations and the improvements used in the new grid. For the two-layer model, we demonstrate the utility of contours on the mass-radius diagrams. Given the mass and radius input, these contours can be used to quickly determine the important physical properties of a planet including its p0 (central pressure), p1/p0 (core-mantle boundary pressure over central pressure), CMF (core mass fraction) or CRF (core radius fraction). For the three-layer model, a curve segment on the ternary diagram represents all possible relative mass proportions of the three layers for a given mass-radius input. These ternary diagrams are tabulated with the intent to make comparison to observations easier. How the presence of Fe in the mantle affects the mass-radius relations is also discussed in a separate section. A dynamic and interactive tool to characterize and illustrate the interior structure of exoplanets built upon models in this article is available online.

Characterizing K2 Planet Discoveries: A Super-Earth Transiting the Bright K Dwarf HIP 116454

We report the first planet discovery from the two-wheeled Kepler (K2) mission: HIP 116454 b. The host star HIP 116454 is a bright (V = 10.1, K = 8.0) K1 dwarf with high proper motion and a parallax-based distance of 55.2 ± 5.4 pc. Based on high-resolution optical spectroscopy, we find that the host star is metal-poor with (Fe/H) =− 0.16 ± 0.08 and has a radius R� = 0.716 ± 0.024 Rand mass M� = 0.775 ± 0.027 M� . The star was observed by the Kepler spacecraft during its Two-Wheeled Concept Engineering Test in 2014 February. During the 9 days of observations, K2 observed a single transit event. Using a new K2 photometric analysis technique, we are able to correct small telescope drifts and recover the observed transit at high confidence, corresponding to a planetary radius of Rp = 2.53 ± 0.18 R⊕. Radial velocity observations with the HARPS-N spectrograph reveal a 11.82 ± 1.33 M⊕ planet in a 9.1 day orbit, consistent with the transit depth, duration, and ephemeris. Follow-up photometric measurements from the MOST satellite confirm the transit observed in the K2 photometry and provide a refined ephemeris, making HIP 116454 b amenable for future follow-up observations of this latest addition to the growing population of transiting super-Earths around nearby, bright stars.

Mass-Radius Relation for Rocky Planets based on PREM

Several small dense exoplanets are now known, inviting comparisons to Earth and Venus. Such comparisons require translating their masses and sizes to composition models of evolved multi-layer-interior planets. Such theoretical models rely on our understanding of the Earths interior, as well as independently derived equations of state (EOS), but have so far not involved direct extrapolations from Earths seismic model -PREM. In order to facilitate more detailed compositional comparisons between small exoplanets and the Earth, we derive here a semi-empirical mass-radius relation for two-layer rocky planets based on PREM:

Kepler-93b: A Terrestrial World Measured to within 120 km, and a Test Case for a New Spitzer Observing Mode

{\frac{R}{R_\oplus}} = (1.07-0.21\cdot \text{CMF})\cdot (\frac{M}{M_\oplus})^{1/3.7}

A Computational Tool to Interpret the Bulk Composition of Solid Exoplanets based on Mass and Radius Measurements

, where CMF stands for Core Mass Fraction. It is applicable to 1

Kepler-21b: A Rocky Planet Around a V = 8.25 Magnitude Star

\sim

THE EFFECT OF TEMPERATURE EVOLUTION ON THE INTERIOR STRUCTURE OF H2O-RICH PLANETS

8 M

Eyes on K2-3: A system of three likely sub-Neptunes characterized with HARPS-N and HARPS

_{\oplus}

Survival function analysis of planet size distribution with Gaia Data Release 2 updates

and CMF of 0.0

Exoplanet Radius Gap Dependence on Host Star Type

\sim