Presentation #102.127 in the session Poster Session.
NASA’s TESS space mission has detected thousands of planet candidates transiting bright stars (V<12). While short-period (P<15 d) planets are being confirmed and characterized by the scientific community using ground-based facilities, most of the longer period (P > 15 d) small planet candidates with single transit events in TESS light curves are still awaiting confirmation, mainly owing to the lack of knowledge of their orbital periods.
Here we report on the discovery and confirmation of three mini-Neptunes transiting the F8 V star TOI-261, which was observed by TESS in Sector 3 and 30. The two inner candidates, namely, TOI-261.01 and 02, were detected and announced by the TESS team, and reported to have periods of 3.4 and 13 days. We confirm the detection of TOI-261.01 but find a different period of 10.2 days for TOI-261.02. We also discover a single transit in Sector 3 light curve and a possibly second transit event in Sector 30, leading to a large number of period aliases for the outer planet candidate. Radial velocity follow-up observations from our HARPS large program confirm the three planets and allow us to measure the orbital period of the outer planet (22.8 d), while providing masses between 8 and 11 MEarth for the three mini-Neptunes.