Overview
- The revised analysis, published in The Astrophysical Journal and led by Paul Robertson, combined high‑precision radial‑velocity data from HPF, NEID, SPIRou and CARMENES and lowered GJ 3378 b’s minimum mass to about 2.3 Earth masses while shortening its orbital period to roughly 21.45 days.
- The planet orbits a red dwarf about 25 light‑years away and receives about 90 percent of the starlight Earth gets from the Sun, placing it inside the conservative liquid‑water habitable zone.
- The lower mass moves GJ 3378 b from the uncertain 5‑Earth‑mass boundary toward a rocky super‑Earth classification, but its radius and density remain unknown because the planet does not transit its star.
- Whether the world can hold an atmosphere is unresolved because close‑in planets around active M dwarfs face strong high‑energy radiation that can strip air, a situation researchers describe as straddling the “cosmic shoreline.”
- Because GJ 3378 b is nearby and now looks likeliest to be rocky, astronomers say the next step is direct imaging and spectroscopic follow‑up with large telescopes such as the GMT, ELT and future missions to search for an atmosphere and possible biosignatures.