Work

Astrometric planet search around southern ultracool dwarfs

Year: 2026

Type: article

Abstract: We report the discovery of PALTA-1 b, a sub-Jupiter mass exoplanet candidate orbiting the nearby early-L dwarf DENIS-P J1253108–570924 (DE1253–57) located at a distance of ~17 pc. The exoplanet was discovered by monitoring the L dwarf’s astro-metric motion with FORS2 at the Very Large Telescope over more than eight years and characterising the deviations from the expected single-source motion. The estimated planet mass is between 0.54 M Jup and 0.77 M Jup , depending on the uncertain mass of the ultracool dwarf host. The system’s mass ratio is about 0.010, and the relative separation is estimated at 1.6–3.4 au. If confirmed, PALTA-1 b would be one of the very few known examples of a giant planet orbiting a nearby ultracool dwarf. This discovery finalises a larger astrometric planet search survey that targeted 20 nearby ultracool dwarfs and previously discovered three new ultracool binary systems.

Source: Astronomy and Astrophysics

DOI: 10.1051/0004-6361/202660121

Authors: J. Sahlmann, P. F. Lazorenko, E. L. Martín, D. Ségransan, M. Mayor, S. Udry