Andrew McNeill et al 2018 ApJL 857 L1
The interstellar asteroid 1I/’Oumuamua is found to have a density range 1500 < ρ < 2800 kg/m3, which requires no significant cohesive strength to hold together. The authors estimate its aspect ratio at 6 ± 1:1.
Nikolaos Georgakarakos et al 2018 ApJ 856 155
A study of 147 planetary systems suggests that the presence of “giant neighbors” can reduce a terrestrial planet’s chances to remain habitable, but they can also occasionally increase the extent of habitable zones.
Ariel Graykowski and David Jewitt 2018 AJ 155 184
An optical color survey of 43 irregular satellites of our outer planets reveals a depletion of ultrared matter, though it’s abundant in the Kuiper Belt and Centaur populations. This hints at the populations’ different origins.
Ravi Kumar Kopparapu et al 2018 ApJ 856 122
A new classification scheme organizes exoplanets into different categories based on their size and incident stellar flux. These categories are then used to predict exoplanet yields for future direct imaging missions.
Natasha E. Batalha et al 2018 ApJL 856 L34
JWST has the potential to detect the dominant absorbing gas in the atmospheres of temperate terrestrial planets by the 10th transit using transmission spectroscopy techniques in the near-infrared.
A. M. Meisner et al 2018 AJ 155 166
The deepest and widest-area WISE search for Planet Nine to date — covering more than 75% of the sky and incorporating 4 years of WISE observations spanning a 7-year period — found no indication of Planet Nine.