The masses and radii of exoplanets are fundamental quantities needed for their characterisation. Studying the different populations of exoplanets is important for understanding the demographics of the different planetary types, which can then be linked to planetary formation and evolution. We present an updated exoplanet catalogue based on reliable, robust, and, as much as possible accurate mass and radius measurements of transiting planets up to 120 M ⊕ . The resulting mass-radius (M-R) diagram shows two distinct populations, corresponding to rocky and volatile-rich exoplanets which overlap in both mass and radius. The rocky exoplanet population shows a relatively small density variability and ends at mass of ~25 M ⊕ , possibly indicating the maximum core mass that can be formed. We use the composition line of pure water to separate the two populations, and infer two new empirical M-R relations based on this data: M = (0.9 ± 0.06) R (3.45±0.12) for the rocky population, and M = (1.74 ± 0.38) R (1.58±0.10) for the volatile-rich population. While our results for the two regimes are in agreement with previous studies, the new M-R relations better match the population in the transition region from rocky to volatile-rich exoplanets, which correspond to a mass range of 5–25 M ⊕ , and a radius range of 2–3 R ⊕ .

https://www.aanda.org/articles/aa/pdf/2020/02/aa36482-19.pdf

Revisited mass-radius relations for exoplanets below 120 M ⊕

The masses and radii of exoplanets are fundamental quantities needed for their characterisation. Studying the different populations of exoplanets is important for understanding the demographics of the different planetary types, which can then be linked to planetary formation and evolution. We present an updated exoplanet catalog based on reliable, robust and as much as possible accurate mass and radius measurements of transiting planets up to 120 $M_{\oplus}$. The resulting mass-radius (M-R) diagram shows two distinct populations, corresponding to rocky and volatile-rich exoplanets which overlap in both mass and radius. The rocky exoplanet population shows a relatively small density variability and ends at mass of $\sim25 M_{\oplus}$, possibly indicating the maximum core mass that can be formed. We use the composition line of pure-water to separate the two populations, and infer two new empirical M-R relations based on this data: $ M = (0.9 \pm 0.06) \ R^{(3.45 \pm 0.12)}$ for the rocky population, and $ M = (1.74 \pm 0.38) \ R^{(1.58 \pm 0.10)}$ for the volatile-rich population. While our results for the two regimes are in agreement with previous studies, the new M-R relations better match the population in the transition-region from rocky to volatile-rich exoplanets, which correspond to a mass range of 5-25 $M_{\oplus}$ and a radius range of 2-3 $R_{\oplus}$.

/pdf/revisited-mass-radius-relations-for-exoplanets-below-120-5ek2umwd1k.pdf

Revisited Mass-Radius relations for exoplanets below 120 Earth masses.

Over the past three decades, we have witnessed one of the great revolutions in our understanding of the cosmos - the dawn of the Exoplanet Era. Where once we knew of just one planetary system (the Solar system), we now know of thousands, with new systems being announced on a weekly basis. Of the thousands of planetary systems we have found to date, however, there is only one that we can study up-close and personal - the Solar system. 
In this review, we describe our current understanding of the Solar system for the exoplanetary science community - with a focus on the processes thought to have shaped the system we see today. In section one, we introduce the Solar system as a single well studied example of the many planetary systems now observed. In section two, we describe the Solar system's small body populations as we know them today - from the two hundred and five known planetary satellites to the various populations of small bodies that serve as a reminder of the system's formation and early evolution. In section three, we consider our current knowledge of the Solar system's planets, as physical bodies. In section four, we discuss the research that has been carried out into the Solar system's formation and evolution, with a focus on the information gleaned as a result of detailed studies of the system's small body populations. In section five, we discuss our current knowledge of planetary systems beyond our own - both in terms of the planets they host, and in terms of the debris that we observe orbiting their host stars. 
As we learn ever more about the diversity and ubiquity of other planetary systems, our Solar system will remain the key touchstone that facilitates our understanding and modelling of those newly found systems, and we finish section five with a discussion of the future surveys that will further expand that knowledge.

Solar System Physics for Exoplanet Research

Jupiter's Gravity Field Halfway Through the Juno Mission

A planetary atmosphere is the outer gas layer of a planet. Besides its scientific significance among the first and most accessible planetary layers observed from space, it is closely connected with planetary formation and evolution, surface and interior processes, and habitability of planets. Current theories of the planetary atmosphere were primarily obtained through the studies of eight large planets, Pluto and three large moons (Io, Titan, and Triton) in the Solar System. Outside the Solar System, more than four thousand extra-solar planets (exoplanets) and two thousand brown dwarfs have been confirmed in our galaxy, and their population is rapidly growing. The rich information from these exotic bodies offers a database to test, in a statistical sense, the fundamental theories of planetary climates. Here we review the current knowledge of atmospheres of exoplanets and brown dwarfs from recent observations and theories. This review highlights important regimes and statistical trends in an ensemble of atmospheres as an initial step towards fully characterizing diverse substellar atmospheres, that illustrates the underlying principles and critical problems. Insights are obtained through analysis of the dependence of atmospheric characteristics on basic planetary parameters. Dominant processes that influence atmospheric stability, energy transport, temperature, composition, and flow pattern are discussed and elaborated with simple scaling laws. We dedicate this review to Dr. Adam P. Showman (1968-2020) in recognition of his fundamental contribution to the understanding of atmospheric dynamics on giant planets, exoplanets, and brown dwarfs.

Atmospheric regimes and trends on exoplanets and brown dwarfs

The interior structure of Saturn, the depth of its winds, and the mass and age of its rings constrain its formation and evolution. In the final phase of the Cassini mission, the spacecraft dived between the planet and its innermost ring, at altitudes of 2600 to 3900 kilometers above the cloud tops. During six of these crossings, a radio link with Earth was monitored to determine the gravitational field of the planet and the mass of its rings. We find that Saturn's gravity deviates from theoretical expectations and requires differential rotation of the atmosphere extending to a depth of at least 9000 kilometers. The total mass of the rings is (1.54 ± 0.49) × 1019 kilograms (0.41 ± 0.13 times that of the moon Mimas), indicating that the rings may have formed 107 to 108 years ago.

/pdf/measurement-and-implications-of-saturn-s-gravity-field-and-2no1l9nqmq.pdf

A. Anabtawi

Papers

Measurement and implications of Saturn's gravity field and ring mass.

The Dark Side of Saturn's Gravity