おうし座T型星
HL Tauri (abbreviated HL Tau) is a very young T Tauri star in the constellation Taurus, approximately from Earth in the Taurus Molecular Cloud. The luminosity and effective temperature of imply that its age is less than 100,000 years. At apparent magnitude 15.1, it is too faint to be seen with the unaided eye. It is surrounded by a protoplanetary disk marked by dark bands visible in submillimeter radiation that may indicate a number of planets in the process of formation. It is accompanied by the Herbig–Haro object , a jet of gas emitted along the rotational axis of the disk that is colliding with nearby interstellar dust and gas.