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.

B. P. Abbott et al 2017 ApJ 839 12

Searches for gravitational waves from 200 pulsars using data from the first observing run of the Advanced LIGO detectors yielded no significant detections, but they were able to set constraining upper limits.

Brian E. Wood et al 2017 ApJS 229 29

31 out of 48 magnetic clouds observed near Earth between 2008–2012 can be clearly connected with a coronal mass ejection that is trackable in STEREO imagery all the way from the Sun to near 1 AU.