| Abstract : | An outcome of studying transiting planets around M dwarfs is the revelation of a bimodal distribution of planets, with peaks at 1.3 R_earth and 2.6 R_earth. The relative paucity of planets between 1.5 R_earth and 1.8 R_earth is termed as the radius valley. Formation of planets in a gas poor environment wherein substantial Hydrogen (H) could not be accreted or the scenario wherein the outer H atmosphere is eroded by XUV irradiation in the initial 100 Myrs of planet formation are the two most promising theories to explain the lack of planets in the radius valley. We have observed several M dwarf transiting systems with the space-based satellite TESS and performed follow-up radial velocity (RV) observations with the optical and NIR spectrograph, CARMENES, fiber-coupled with the 3.5-meter telescope at the Observatorio de Calar Alto in Almer\'ia (Spain). We would report the discovery and characterization of a handful multi-planetary systems detected on each side of the radius valley, particularly focussing on one example for the M3.0 V star TOI-1468 having two planets straddling the radius valley. The inner planet has a rocky composition and the outer one is consistent with a rocky core with a H/He gas envelope. Similar discoveries can further help determine a more precise location of the radius valley for small planets around M dwarfs and, therefore, shed more light on planet formation and evolution scenarios. |
