Presentation #102.204 in the session Poster Session.
Small planets transiting bright nearby stars are essential to our understanding of the formation and evolution of exoplanetary systems. Few of those constitute prime targets for atmospheric characterization, and even fewer are part of multiple star systems. In this context, TESS has provided a wealth of interesting transiting planet candidates. Among those is TOI-4336.01, an exciting temperate mini-Neptune of radius 2.16±0.09 Re orbiting an M4.5-type star member of a wide triple M-dwarf system located at 22 pc.
We fully validate the planetary nature of TOI-4336.01 through (1) the global analysis of TESS data and follow-up multi-band high precision photometric data from the TRAPPIST-South, SPECULOOS-South and LCO ground-based telescopes, (2) medium-resolution spectroscopy of the host star, (3) high-resolution imaging, and (4) archival images.
Its period of 16.33 days remarkably places it near the inner edge of the conservative habitable zone with an equilibrium temperature of 319K. Added to the relatively large brightness of the host star in K band (8.63), this makes it an ideal candidate for atmospheric studies through transmission spectroscopy, with a Transmission Spectroscopy Metric (Kempton et al., 2018) between 90 and 100. A first step will be our upcoming exploratory observations with the HST/WFC3 (GO program ID 16875) to assess the extent of the atmosphere and distinguish between a cloudy scenario and a clear one, possibly revealing the presence of water.