The HD 260655 system: Two rocky worlds transiting a bright M dwarf at 10 pc

We report the discovery of a multi-planetary system transiting M0 V dwarf HD 260655 (GJ 239, TOI-4599). The consists at least two planets, namely b, with period 2.77 d, radius R$_b$ = 1.240$\pm$0.023 R$_\oplus$, mass M$_b$ 2.14$\pm$0.34 M$_\oplus$, and bulk density $\rho_b$ 6.2$\pm$1.0 g cm$^{-3}$, c, 5.71 R$_c$ 1.533$^{+0.051}_{-0.046}$ M$_c$ 3.09$\pm$0.48 $\rho_c$ 4.7$^{+0.9}_{-0.8}$ cm$^{-3}$. planets were detected in transit by TESS mission confirmed independently archival new precise radial velocities obtained HIRES CARMENES instruments since 1998 2016, respectively. At distance 10 pc, becomes fourth closest known multi-transiting planet after 219134, LTT 1445 A, AU Mic. Due to apparent brightness host star (J 6.7 mag), both are among most suitable rocky worlds today for atmospheric studies JWST, transmission emission.