Flash of light from erupting star T Pyxidis illuminates debris disc

These three images taken by the NASA/ESA Hubble Space Telescope reveal a disc of previously-ejected material around an erupting star. This disc is being illuminated by a torrent of light unleashed during a stellar outburst.

Hubble's Wide Field Camera 3 imaged the double-star system T Pyxidis, or T Pyx, over a four-month period. T Pyx is a recurrent nova, erupting every 12 to 50 years. T Pyx's latest outburst was in April 2011. The star is the white blob in the middle of each image.

Astronomers used Hubble to trace the path of the light emitted from the outburst as it lit up the disc and material from previous ejecta. The white ovals in each image highlight the areas being illuminated by the light. The disc is so vast, about a light-year across, that the nova's light cannot brighten all of the material at once. Instead, the light sweeps across the material, sequentially illuminating parts of the disk, a phenomenon called a light echo. The light reveals which parts of the disc are nearer to Earth and which ones are farther away. By tracing the light, the team assembled a 3-D map of the structure around the nova.

A nova erupts when a white dwarf, the burned-out core of a Sun-like star, has siphoned enough hydrogen off a companion star to trigger a thermonuclear runaway. As hydrogen builds up on the surface of the white dwarf, it becomes hotter and denser until it detonates like a colossal hydrogen bomb, leading to a 10,000-fold increase in brightness in little more than a day.

T Pyx is located over 15,000 light-years away in the southern constellation of Pyxis (The Mariner's Compass). The images were taken on the 16th September, 16th November, and 10th December 2011.

Link:

• NASA Press release