Time-lapse movies made from a series of pictures taken by NASA's Hubble Space Telescope are showing astronomers that young stars and their surroundings can change dramatically in just weeks or months. As with most children, a picture of these youngsters taken today won't look the same as one snapped a few months from now. The movies show jets of gas plowing into space at hundreds of thousands of miles per hour and moving shadows billions of miles in size.
The young star systems featured in the movies, XZ Tauri and HH 30, reside about 450 light-years from Earth in the Taurus-Auriga molecular cloud, one of the nearest stellar nurseries to our planet. Both systems are probably less than a million years old, making them relative newborns, given that stars typically live for billions of years. Hubble's Wide Field and Planetary Camera 2 first observed them in 1995. Those views were so intriguing that additional images were taken in 1998, 1999, and 2000. The pictures were then combined into movies that document startling activity in the early stages of a star's life.
Stars form in clouds of gas and dust that collect into a swirling disk. Outflows of gas, like the bubbles and jets seen in these images, occur when some of the material feeding the infant star from the surrounding disk is diverted away by the star's magnetic field and accelerated out its magnetic poles. These outflows are often squeezed into narrow jets that can extend many light-years away from the star. Such outflows are a common and natural result of stellar birth.
XZ Tauri Credits: NASA, John Krist (Space Telescope Science Institute), Karl Stapelfeldt (Jet Propulsion Laboratory), Jeff Hester (Arizona State University), Chris Burrows (European Space Agency/Space Telescope Science Institute)
HH 30 Credits: NASA, Alan Watson (Universidad Nacional Autonoma de Mexico, Mexico), Karl Stapelfeldt (Jet Propulsion Laboratory), John Krist (Space Telescope Science Institute) and Chris Burrows (European Space Agency/ Space Telescope Science Institute)