We search for signatures of a distant planet around the two-million-year-old classical T-Tauri star CI Tau hosting a hot Jupiter candidate ( M _ { p } \sin { i } \sim 8.1 ~ { } M _ { Jupiter } ) in an eccentric orbit ( e \sim 0.3 ) .
To probe the existence of an outer perturber , we reanalyzed 1.3 mm dust continuum observations of the protoplanetary disk around CI Tau obtained by the Atacama Large Millimeter/submillimeter Array .
We found a gap structure at \sim 0 \farcs 8 in CI Tau ’ s disk .
Our visibility fitting assuming an axisymmetric surface brightness profile suggested that the gap is located at a deprojected radius of 104.5 \pm 1.6 au and has a width of 36.9 \pm 2.9 au .
The brightness temperature around the gap was calculated to be \sim 2.3 K lower than that of the ambient disk .
Gap-opening mechanisms such as secular gravitational instability and dust trapping can explain the gap morphology in the CI Tau disk .
The scenario that an unseen planet created the observed gap structure can not be ruled out , although the coexistence of an eccentric hot Jupiter and a distant planet around the young CI Tau would be challenging for gravitational scattering scenarios .
The mass of the planet was estimated to be between \sim 0.25 M _ { Jupiter } and \sim 0.8 M _ { Jupiter } from the gap width and depth ( 0.41 ^ { +0.04 } _ { -0.06 } ) in the modeled surface brightness image , which is lower than the current detection limits of high-contrast direct imaging .
The young classical T-Tauri CI Tau may be a unique system to explore the existence of a potential distant planet as well as the origin of an eccentric hot Jupiter .