First light from a young star?

Abstract

The early phases of stellar evolution are frequently characterized by vigorous interaction between the nascent star and its environment, resulting in the formation of molecular outflows, highly collimated jets, Herbig-Haro objects and small emission or reflection nebulae. A deep survey of such small nebulae around young stars in the Orion molecular clouds has recently been completed¹. We report here the sudden appearance of a highly variable, conical nebula (Object 50) 1.5 arc min south of a 250L_⊙ infrared source in the southern part of the L1641 cloud in Orion. The nebula coincides with the edge of the approaching lobe of a 10⁵-yr-old bipolar molecular outflow. Variability of the infrared source generates light pulses observed to propagate through the surrounding ambient cloud, producing a fluctuating illumination pattern. This emission may represent the first optical radiation to have emerged from this newborn star.