Context : Recent observational results show that very low mass stars and brown dwarfs are able to host close-in rocky planets .
Low-mass stars are the most abundant stars in the Galaxy , and the formation efficiency of their planetary systems is relevant in the computation of a global probability of finding Earth-like planets inside habitable zones .
Tidal forces and relativistic effects are relevant in the latest dynamical evolution of planets around low-mass stars , and their effect on the planetary formation efficiency still needs to be addressed .

Aims : Our goal is to evaluate the impact of tidal forces and relativistic effects on the formation of rocky planets around a star close to the substellar mass limit in terms of the resulting planetary architectures and its distribution according to the corresponding evolving habitable zone .

Methods : We performed a set of N -body simulations spanning the first 100 Myr of the evolution of two systems composed of 224 embryos with a total mass 0.25M _ { \oplus } and 74 embryos with a total mass 3 M _ { \oplus } around a central object of 0.08 M _ { \odot } .
For these two scenarios we compared the planetary architectures that result from simulations that are purely gravitational with those from simulations that include the early contraction and spin-up of the central object , the distortions and dissipation tidal terms , and general relativistic effects .

Results : We found that including these effects allows the formation and survival of a close-in ( r < 0.07 au ) population of rocky planets with masses in the range 0.001 < m / \mathrm { M _ { \oplus } } < 0.02 in all the simulations of the less massive scenario , and a close-in population with masses m \sim 0.35 M _ { \oplus } in just a few of the simulations of the more massive scenario .
The surviving close-in bodies suffered more collisions during the integration time of the simulations .
These collisions play an important role in their final masses .
However , all of these bodies conserved their initial amount of water in mass throughout the integration time .

Conclusions : The incorporation of tidal and general relativistic effects allows the formation of an in situ close-in population located in the habitable zone of the system .
This means that both effects are relevant during the formation of rocky planets and their early evolution around stars close to the substellar mass limit , in particular when low-mass planetary embryos are involved .