T. Wevers et al 2021 ApJ 912 151
Multiwavelength observations of the TDE AT2018fyk over two years show three distinct accretion states and two state transitions between them, very similar to the behavior of stellar-mass black holes in outburst.
Shantanu P. Naidu et al 2021 ApJL 913 L6
Observations of 2020 CD3 from the Dark Energy Camera and Catalina Sky survey from 2018–19 allow us to calculate that this asteroid was captured into a geocentric orbit in September 2017, temporarily becoming a minimoon.
Trevor J. David et al 2021 AJ 161 265
A study of systems in the California–Kepler Survey sample suggests that the size distribution of close-in exoplanets and the precise location of the radius valley — a bifurcation in this distribution — evolve over gigayears.
I. Tovar et al 2021 ApJ 912 122
Analysis of a series of measurements of the solar diameter taken 1655–1736 in the meridian line of the Basilica of San Petronio (Bologna, Italy) indicate there was no increase in solar diameter during the Maunder Minimum.
Jiaming Liu et al 2021 ApJS 254 20
A systematic search for stellar groups in the Taurus field has yielded 22 groups, including 8 young (2–4 Myr) groups at distances of ~130–170 pc, and 14 old (8–49 Myr) groups at distances of ~110–210 pc.
S. E. Woosley and Alexander Heger 2021 ApJL 912 L31
New calculations explore four factors affecting the theoretical boundaries of the pair instability black-hole mass gap: nuclear reaction rates, evolution in detached binaries, rotation, and hyper-Eddington accretion after birth.