V. A. Acciari et al 2020 ApJS 248 29

Observations of the TeV blazar Mrk 421 during flaring activity show energy-dependent variability on multi-hour timescales and energy-independent variability on sub-hour timescales, favoring a multi-zone scenario.

Yong Zheng et al 2020 ApJ 896 143

Synthetic observations of simulated Milky Way analogs demonstrate and quantify multiple observational biases that are at play when we study the Milky Way’s circumgalactic medium.

Matija Ćuk et al 2020 Planet. Sci. J. 1 22

Simulations of the past tidal evolution of the Uranian system suggest that the most recent major mean–motion resonance between two large moons, Ariel and Umbriel, greatly influenced the system’s current confirguration.

Noé Brucy et al 2020 ApJL 896 L34

Models show that stellar feedback is not sufficient to regulate star formation in gas-rich high-redshift galaxies, but external driving of turbulence could further reduce the star formation rate to that observed.

Elia Leibowitz 2020 ApJ 896 74

Periodic modulation of Sgr A*’s X-ray and near-infrared flaring activity can be interpreted as due to a close-in (within 3–3.5 Schwarzschild radii of the black hole) star on a slightly elliptical precessing orbit.

W. F. Bottke et al 2020 AJ 160 14

Empirically derived asteroid crater scaling laws suggest crater retention ages of ~1 Gyr for Bennu, Ryugu, and Itokawa and ~2.5 Gyr for Toutatis, agreeing with the estimated formation ages of their source families.