We present the characterisation of the TOI-6041 system, a bright (V = 9. 84 ± 0. 03) G7-type star hosting at least two planets. The inner planet, TOI-6041, b, is a warm Neptune with a radius of +0. 18 _ -0. 17, R_⊕, initially identified as a single-transit event in TESS photometry. Subsequent observations with TESS and CHEOPS revealed additional transits, enabling the determination of its 26. 04945^ +0. 00033 _ -0. 00034 d orbital period and the detection of significant transit-timing variations (TTVs), exhibiting a peak-to-peak amplitude of about 1 hour. Radial-velocity (RV) measurements obtained with the APF spectrographs allowed us to place a 3σ upper mass limit of 28. 9, M_⊕ on TOI-6041, b. In addition, the RV data reveal a second companion, TOI-6041, c, on an 88 d orbit, with a minimum mass of 0. 25, M_ Jup. A preliminary TTV analysis suggested that the observed variations could be caused by gravitational perturbations from planet, c; however, reproducing the observed amplitudes requires a relatively high eccentricity of about 0. 3 for that planet. Our dynamical stability analysis indicates that such a configuration is dynamically viable and places a 1σ upper limit on the mass of TOI-6041, c at 0. 8, M_ Jup. An alternative is the presence of a third, low-mass planet located between planets, b and, c, or on an inner orbit relative to planet b—particularly near a mean-motion resonance with planet, b—which could account for the observed variations. These findings remain tentative, and further RV and photometric observations are essential in to better constrain the mass of planet b and to refine the TTV modeling, thereby improving our understanding of the system's dynamical architecture.
Heidari et al. (Thu,) studied this question.