| Summary: | The Transiting Exoplanet Survey Satellite (TESS) mission has enabled discoveries of the brightest transiting planet
systems around young stars. These systems are the benchmarks for testing theories of planetary evolution. We
report the discovery of a mini-Neptune transiting a bright star in the AB Doradus moving group. HIP 94235 (TOI4399, TIC 464646604) is a Vmag = 8.31 G-dwarf hosting a 3.00 0.28 R 0.32
-
+
Å mini-Neptune in a 7.7 day period orbit.
HIP 94235 is part of the AB Doradus moving group, one of the youngest and closest associations. Due to its youth,
the host star exhibits significant photometric spot modulation, lithium absorption, and X-ray emission. Three
0.06% transits were observed during Sector 27 of the TESS Extended Mission, though these transit signals are
dwarfed by the 2% peak-to-peak photometric variability exhibited by the host star. Follow-up observations with
the Characterising Exoplanet Satellite confirmed the transit signal and prevented the erosion of the transit
ephemeris. HIP 94235 is part of a 50 au G-M binary system. We make use of diffraction limited observations
spanning 11 yr, and astrometric accelerations from Hipparcos and Gaia, to constrain the orbit of HIP 94235 B. HIP
94235 is one of the tightest stellar binaries to host an inner planet. As part of a growing sample of bright, young
planet systems, HIP 94235 b is ideal for follow-up transit observations, such as those that investigate the
evaporative processes driven by high-energy radiation that may sculpt the valleys and deserts in the Neptune
population.
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