The pristine shell is the visible remnant of a powerful stellar explosion, or supernova, in the Large Magellanic Cloud, which is a small galaxy about 160,000 light-years away from Earth. [Hubble's new space bubble photo]
The festive bubble, formally known as SNR 0509-67.5 (or SNR 0509 for short), is the result of gas that is being shocked by the expanding blast wave from the supernova explosion.
Astronomers think the stellar explosion was a Type Ia supernova, which is an especially energetic and bright variety. Type Ia events are thought to result from a white dwarf star in a binary, or two-star, system that robs its partner of material, taking on more mass than it is able to handle, which eventually results in a violent explosion.
The rippling effect that can be seen in the shell's surface may be caused by subtle variations in the density of the surrounding interstellar gas, the researchers said. The undulations could also be driven from the interior of the bubble by pieces of the ejecta.
The sphere of gas measures about 23 light-years across, and is expanding at more than 11 million mph (about 18 million kph).
The Hubble Space Telescope's Advanced Camera for Surveys observed the SNR 0509 supernova remnant on Oct. 28, 2006 using a filter that isolates light from glowing hydrogen seen in the expanding shell. These observations were then combined with visible light images of the surrounding star field that were captured by Hubble on Nov. 4, 2010.
As seen from Earth, the supernova – which is about 400 years old – might have been visible to southern hemisphere observers around the year 1600.
There are, however, no known records of a "new star" in the direction of the Large Magellanic Cloud near that time.
Decades earlier, famed 16th century astronomer Tycho Brahe did spot what he called a "new star" in the sky in 1527. That star turned out to be the supernova explosion of a star in the constellation Cassiopeia, and was visible from the northern hemisphere, not southern.
A more recent supernova from that galaxy, called SN 1987A, caught the eye of Earth viewers, and continues to be studied with ground- and space-based telescopes, including Hubble.