Prabal Saxena et al 2019 ApJL 876 L16

The observed degree of depletion of sodium and potassium in lunar samples and the evolution of activity of solar analogs over time suggest that the primordial Sun is highly likely to have been a slow rotator.

Ashley Chontos et al 2019 AJ 157 192

KOI 4.01, Kepler’s first discovered planet candidate, has finally been confirmed via a combination of asteroseismology and radial velocities; it is the closest known planet in terms of orbital period to an evolved star.

Alexandre Emsenhuber and Erik Asphaug 2019 ApJ 875 95

In similar-sized planetary collisions, a significant part of the impactor often continues downrange. Roughly 50% of these “runners” reimpact their target planets; the others remain in orbit for tens of millions of years.

Dong-Woo Kim et al 2019 ApJS 241 36

In a new project, spatially resolved 2D spectral maps have been created of the hot gas from 70 individual early-type galaxies; they are available for general use at the Chandra Galaxy Atlas (CGA) website.

Stephanie H. Ho et al 2019 ApJ 875 54

Cosmological hydrodynamic simulations suggest that cold gas accretes onto galaxies anisotropically and it can plausibly account for sustaining the star-forming activities of many galaxies.

David V. Martin et al 2019 ApJL 875 L25

Calculations suggest that a Neptune-sized exomoon candidate in the Kepler-1625 system may only transit ~40% of the time, suggesting ~6 non-transits would be required to confidently rule out the moon’s existence.