Magellan/PFS Radial Velocities of GJ 9827, a late K dwarf at 30 pc with Three Transiting Super-Earths

Understand

The Kepler mission showed us that planets with sizes between that of Earth and Neptune appear to be the most common type in our Galaxy.

• These "super-Earths" continue to be of great interest for exoplanet formation, evolution, and composition studies.
• However, the number of super-Earths with well-constrained mass and radius measurements remains small (40 planets with $\sigma_{\rm{mass}}<$ 25\%), due in part to the faintness of their host stars causing ground-based mass measurements to be challenging.
• Recently, three transiting super-Earth planets were detected by the K2 mission around the nearby star GJ 9827/HIP 115752, at only 30 pc away.