Red dwarf

Astronomers at the University of California, Irvine, have revised the orbital characteristics of GJ 3378 b, a super-Earth located 25 light-years away. New data from the Habitable-zone Planet Finder and the NEID spectrometer indicates the planet orbits its host red dwarf star every 21.45 ± 0.01 days, rather than the previously estimated 24.73 ± 0.06 days. This adjustment places the planet firmly within the star’s conservative liquid-water habitable zone, though its potential to retain an atmosphere remains a subject of ongoing scientific inquiry.

Why Did the Orbital Data for GJ 3378 b Change?

The updated orbital model resulted from combining multiple high-precision datasets. According to a study published in The Astrophysical Journal, researchers led by UC Irvine associate professor Paul Robertson integrated measurements from the Hobby-Eberly Telescope’s Habitable-zone Planet Finder (HPF) and the NEID spectrometer at Kitt Peak National Observatory. By incorporating additional data from the SPIRou and CARMENES spectrometers, the team identified that the planet’s year is shorter—21.45 ± 0.01 days—than the initial 24.73 ± 0.06 day estimate. This refined analysis also yielded a lower minimum mass for the planet, increasing the probability that it is a rocky, terrestrial world rather than a gas-shrouded mini-Neptune.

What Is the “Cosmic Shoreline” for Exoplanets?

Researchers use the term “cosmic shoreline” to describe the precarious boundary where a planet’s atmosphere might either persist or be stripped away by stellar radiation. Because GJ 3378 is an M4V red dwarf—a star that churns gases from its core to its surface—it subjects nearby planets to intense radiation. Robertson notes that if Earth were scaled to the size of an apple, its atmosphere would be as thin as the fruit’s skin. This thin layer is essential for maintaining the surface pressure required for liquid water and providing protection from space radiation. It remains unclear whether GJ 3378 b possesses a sufficient atmosphere to sustain these conditions or if the star has already stripped it away.

How Do Scientists Search for Life on Nearby Stars?

The discovery process relies on detecting subtle stellar wobbles caused by the gravitational pull of orbiting planets. According to Gogod James, a student in Robertson’s group who worked to characterize the size of GJ 3378b, characterizing the size and atmospheric potential of a planet is the first step toward justifying future research into biosignatures. By focusing on planets within the “Goldilocks” region—where temperatures allow for liquid water—astronomers can narrow their search for environments that might support life. Future observations aim to determine if GJ 3378 b has a stable atmosphere, which is a prerequisite for finding signs of liquid water or biological activity.

Comparison: Previous vs. Revised Orbital Properties

Frequently Asked Questions

Is GJ 3378 b definitely habitable?
Not necessarily. While it sits within the habitable zone, it is unknown if the planet has retained an atmosphere or if it has been stripped away by its host star’s radiation.

How far away is GJ 3378?
The star is located 25 light-years from Earth.

Why is the planet’s mass important?
A lower mass suggests the planet is more likely to be a rocky, terrestrial body rather than a gaseous mini-Neptune, which is a key factor in assessing its potential for life.