Broadband linear polarimetry of exoplanet Upsilon Andromedae b: Constraints on the orbital and physical parameters
: Abdul Qadir, Yasir; Berdyugin, Andrei V.; Kravtsov, Vadim; Piirola, Vilppu; Sakanoi, Takeshi; Kagitani, Masato; Poutanen, Juri
: Landt, Hermine; Dominik, Martin; Oliver, Carol
: Symposium of the International Astronomical Union
Publisher: Cambridge University Press (CUP)
: 2026
Proceedings of the International Astronomical Union
: (Toward) Discovery of Life beyond Earth and its Impact
: 20
: 387
: 87
: 92
: 1743-9213
: 1743-9221
DOI: https://doi.org/10.1017/S174392132400231X
: https://doi.org/10.1017/s174392132400231x
Context. Modern polarimeters enable precise measurements of exoplanetary systems, providing valuable constraints on orbital geometry and atmospheric scattering properties.
Aims. We aim to investigate the orbital parameters of the non-transiting Jupiter-like exoplanet υ And b, which orbits close to its host star, using polarized scattered light observed with the DiPol-2 polarimeter on a 60 cm telescope.
Methods. Over nearly three years, we collected high-precision polarimetric data of the υ And system. Using Lomb-Scargle periodograms, we identified variability close to the planetary orbital phase and modeled the signal with the Rayleigh-Lambert approximation.
Results. A weak polarimetric signal at half the orbital period of υ And b was detected. The V -band MCMC fits yielded an orbital inclination of i = 28+88−18◦, an argument of periastron ω = 102+139−45◦, a longitude of ascending node Ω = 107+134−43◦, and a geometric albedo of p = 19+9−8%. Although uncertainties remain large, the inclination result agrees with earlier estimates, supporting a low-inclination, non-transiting geometry.
Conclusions. While the detection is not definitive, these results demonstrate the capability of high-precision polarimetry to probe the orbital parameters of non-transiting exoplanets. Further observations with larger telescopes and improved sensitivity will be required to refine the constraints on the orbital parameters.