Sub-Neptune GJ 3090 b found on a retrograde, highly tilted orbit around a red dwarf
Astronomers measured the orbital tilt of GJ 3090 b and found the 2.2‑Earth‑radius, 4.5‑Earth‑mass sub‑Neptune orbits its red dwarf host in the opposite direction to the star’s spin, with a spin–orbit angle (Psi) of about 136°. The result, reported Sept. 21 in Astronomy & Astrophysics, was obtained using the NIRPS spectrograph at La Silla Observatory and is surprising because no massive companion is detected to explain the misalignment.