This festive NASA Hubble Space Telescope image resembles a holiday wreath made of sparkling lights. The bright southern hemisphere star RS Puppis, at the center of the image, is swaddled in a gossamer cocoon of reflective dust illuminated by the glittering star. RS Puppis rhythmically brightens and dims over a six-week cycle. It is one of the most luminous in the class of so-called Cepheid variable stars. The nebula flickers in brightness as pulses of light from the Cepheid propagate outwards. Hubble took a series of photos of light flashes rippling across the nebula in a phenomenon known as a “light echo.”
This movie shows the reflection nebula around the Cepheid variable RS Puppis at seven equally spaced intervals during its 41.4-day pulsation period. Each time RS Puppis reaches maximum brightness, it sends another wave of illumination into the surrounding dust. Thus a pattern of apparently expanding bull’s-eyes surrounds the variable star, similar to the ripples in a pond produced when a series of stones is thrown into the water. These images were taken with Hubble’s Advanced Camera for Surveys in a visual filter over the following dates in 2010: March 25 and 31, April 6, 11, 18, 24, and 29. Each individual image in this sequence had an exposure time of 23 minutes.
Credit: NASA, ESA, G. Bacon (STScI), the Hubble Heritage Team (STScI/AURA)-Hubble/Europe Collaboration, and H. Bond (STScI and Pennsylvania State University)
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