T.Pyx is in the constellation Pyxis. Not one of those constellations I get to see being in the north. The star is 16,000 light-years away and is a known recurrent nova.
I had a hard time figuring this one out so I’ll let Hubblesite explain it, looking at the large version of the image helps too.
These three images taken by NASA’s Hubble Space Telescope reveal a disk of previously ejected material around an erupting star 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 disk and material from previous ejecta. The white ovals in each image highlight the areas being illuminated by the light. The disk 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 disk 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 a little more than one day.
T Pyx is located 15,600 light-years away in the southern constellation Pyxis, the Mariner’s Compass. The images were taken Sept. 16, Nov. 16, and Dec. 10, 2011.