The prototypical young cometary nebula NGC 2261, around the star R Mon, has been extensively observed with 20" resolution in the J=1-0 line of CO and 13CO by using the IRAM 30-m telescope (located on the Pico Veleta, near Granada, Spain). The molecular line maps are compared to optical observations in order to obtain
detailed information on the nature of this cometary nebula as well as on the kinematic structure of the gas. Our observations suggest that cometary nebula NGC 2261 is actually the brightest fan of a bipolar nebula. Furthermore, it appears that the optical nebula is a hollow cone which has been emptied by the action of winds from R Mon, the star located at the tip of the nebula. High velocity CO is
flowing along the cone walls. Toward the position of the star R Mon we observe a molecular maximum which could be due to residual material originated during the collapse process that led to the formation of the star.