TOI-1201 b: A mini-Neptune transiting a bright and moderately young M dwarf

We present the discovery of a transiting mini-Neptune around TOI-1201, relatively bright and moderately young early M dwarf ($J \approx$ 9.5 mag, $\sim$600-800 Myr) in an equal-mass $\sim$8 arcsecond-wide binary system, using data from Transiting Exoplanet Survey Satellite (TESS), along with follow-up transit observations. With orbital period 2.49 d, TOI-1201 b is warm radius $R_\mathrm{b} = 2.415\pm0.090 R_\oplus$. This signal also precise radial velocity measurements CARMENES, confirming existence planet providing planetary mass $M_\mathrm{b} 6.28\pm0.88 M_\oplus$ and, thus, estimated bulk density $2.45^{+0.48}_{-0.42}$ g cm$^{-3}$. The spectroscopic observations additionally show evidence 19 d long periodic variation undetermined origin. In combination ground-based photometric monitoring WASP-South ASAS-SN, we attribute to stellar rotation ($P_{rot}=$ 19-23 d), although cannot rule out that seen photometry belongs visually close companion. calculate parameters for both its excellent target atmosphere characterization (the transmission spectroscopy metric $97^{+21}_{-16}$) upcoming James Webb Space Telescope. It feasible measure spin-orbit alignment via Rossiter-McLaughlin effect current state-of-the-art spectrographs submeter per second precision.