NGC 2359 is an H ii region located in the outer Galaxy that contains the isolated Wolf-Rayet ( WR ) star HD 56925 .
We present new CO observations of NGC 2359 with the Nobeyama 45-m radio telescope and the Atacama Submillimeter Telescope Experiment using the ^ { 12 } CO ( J = 1–0 , 3–2 ) emission lines and compare them with archived H i and radio-continuum data from the Very Large Array .
Our purpose is to investigate whether the formation of the WR star in NGC 2359 was triggered by a cloud-cloud collision .
We find two molecular clouds at \sim 37 and \sim 54 km s ^ { -1 } , and two H i clouds at \sim 54 and \sim 63 km s ^ { -1 } .
All are likely to be associated with NGC 2359 as suggested by good morphological correspondence not only with an optical dark lane through the nebula but also with the radio-shell boundary .
We also find that the molecular cloud at \sim 54 km s ^ { -1 } has a high kinematic temperature of at least \sim 40 K , thus indicating that the gas temperature has been increased because of heating by the WR star .
We propose that both NGC 2359 and the isolated WR star were created by a collision between the two molecular clouds .
The supersonic velocity separation of the two clouds can not be explained by stellar feedback from the WR star .
The complementary spatial distributions and bridging features of CO and H i also are in good agreement with the expected observational signatures of high-mass star formations triggered by cloud-cloud collisions .
We argue that NGC 2359 may be in the final phase of a cloud-cloud collision and that the collision timescale is \sim 1.5 Myr or longer .
We also note that there is no significant difference between the physical properties of colliding clouds that trigger the formation of isolated O-type and WR stars .