Charlestown police have announced that a 21-year-old Hopkinton man is the motorcyclist who was killed on Route 1 Monday when an impaired driver lost control of his vehicle.Thomas J. Hug, of 52 Old Hopkinton Cemetery Road, was killed at about 4:11 p.m. Monday.A 17-year-old teen driver has been charged with driving under the influence, death resulting, according to authorities.