on b and c, to the extent that b had to be a sub-Neptune. All the planets from b to at least f must have migrated inward. That study implied that d was a sub-Neptune as well. As such strong tidal forces often result in the destruction of larger natural satellites in planets orbiting close to a star, it is unlikely that HD 40307 d hosts any satellites. See also References External links HD 40307 Pictor (constellation) Super-Earths Exoplanets discovered in 2008 Exoplanets detected by radial velocity Exoplanets in the Gliese Catalog