B. Gompertz and A. Fruchter 2017 ApJ 839 49

Observations suggest that only a magnetar with a spin period of ~1 ms or faster could provide enough energy to power the associated events of the ultra-long gamma-ray burst 111209A and Supernova 2011kl.

Francesca M. Fornasini et al 2017 ApJS 229 33

38 hard X-ray sources are detected by NuSTAR in the direction of the Norma spiral arm, including active galactic nuclei, X-ray binaries, pulsar wind nebulae, and cataclysmic variables.

D. W. Gerdes et al 2017 ApJL 839 L15

A new possible dwarf planet, 2014 UZ224 (“DeeDee”), has been discovered at 92 AU in our solar system. It appears to have a 1140-year orbit and a diameter of ~635 km (roughly a quarter of Pluto’s).

Owen R. Lehmer et al 2017 ApJ 839 32

For icy moons of Ganymede’s size around a Sun-like star, surface water could persist indefinitely outside the runaway greenhouse orbital distance, but smaller moons could lose their icy shells over time.

Steven Janssens et al 2017 ApJL 839 L17

Nearly 2,000 ultra-diffuse galaxies (UDGs) were discovered in the massive galaxy cluster Abell 2744. Observations suggest that ultra-compact dwarfs may be left behind as UDGs fall into the cluster and dissolve.

Karen J. Meech et al 2017 AJ 153 206

Observations show the onset of activity on comet C/2015 ER61 (PANSTARRS) at about r = 8.8 AU in early 2015 — marking the first time we’ve been able to watch a long-period comet turn on.