Planet-Mass Black Holes: Invisible Partners of Stars or the Key to Dark Matter?
Picture a star waltzing with an invisible partner: its rhythmic wobble, caused by the gravitational pull of a companion, is picked up by instruments, yet the partner itself eludes detection. Usually, such wobbles are the result of a Doppler shift, a change in the frequency of light due to the star's motion, that betrays the presence of a planet.