Astronomers have announced the discovery of a "super eccentric" planet orbiting a nearby star.

As astronomical instruments improve, the number of worlds discovered beyond the Solar System continues to rise. Specifically, by the end of January 2025, the existence of over seven thousand exoplanets in more than five thousand planetary systems has been confirmed.

Now, the authors of a new study, the text of which is presented on the Cornell University preprint server, have announced the discovery of 2126 b — an unusual exoplanet with a mass comparable to that of Jupiter. This world completes a full orbit around the star GJ 2126 in approximately 273 days, but its main feature is its "eccentric" orbit.

The discovery was made using the HARPS spectrograph — one of the most precise instruments for measuring radial velocities and searching for exoplanets, installed on the ground-based 3.6-meter telescope at the La Silla Observatory in Chile. Its high sensitivity allows for the measurement of the slightest "wobbles" of the star, resulting from the orbital motion of planets around it. Previously, this "hunter" for exoplanets enabled the detection of a whole "cocktail" of metals in the atmosphere of one of the worlds.

To "track down" the gas giant GJ 2126 b, a research team led by Arbel Schorr from Tel Aviv University (Israel) analyzed the HARPS-RVBank database, which contains over 250,000 measurements of radial velocities for 5,239 stars made with HARPS over 15 years (up to January 2022).

The results showed that the mass of the exoplanet is about 1.3 times that of Jupiter, although the exact value could be higher, depending on the inclination of its orbit, which still needs to be specified. However, this will not be an easy task.

If we imagine the orbit as a "circle," the planets in our Solar System have slightly elongated orbits (less than six percent deviation from a perfect circle). However, the detected planet has an "eccentricity" of about 85 percent, meaning that the gas giant's orbit is much more elongated. This means that at one point in its path, the exoplanet comes very close to the star, while at another point, it is much farther away. Such "eccentric" orbits are extremely rare among similar worlds.

What makes the discovery even more interesting is its parent star — the red dwarf GJ 2126, which is classified as low-mass (with a mass of about 0.65 solar masses). Gas giants are rarely found around such stars, especially with elongated orbits.

The authors of the new scientific paper noted that planets initially form on nearly circular orbits. To acquire such an elongated trajectory as GJ 2126 b, powerful gravitational "perturbations" are needed, such as interactions with other planets, migration in the protoplanetary disk, or "random" stellar flybys.

Further observations will help clarify the inclination of the orbit and the mass of the gas giant. If the astronomers' conclusions are confirmed, the discovery will solidify the status of this exoplanet as having one of the most "eccentric" orbits, as well as allowing scientists to better understand the mechanisms of formation and evolution of planetary systems.