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. The super star is
ten times more massive than our sun and 200 times larger.
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. Its average intrinsic brightness is 15,000 times greater than our
sun’s luminosity.
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." Even
though light travels through space fast enough to span the gap between
Earth and the moon in a little over a second, the nebula is so large
that reflected light can actually be photographed traversing the nebula.
By observing the fluctuation of light in RS Puppis itself, as well as
recording the faint reflections of light pulses moving across the
nebula, astronomers are able to measure these light echoes and pin down a
very accurate distance. The distance to RS Puppis has been narrowed
down to 6,500 light-years (with a margin of error of only one percent).
The Hubble Space Telescope is a project of international cooperation
between NASA and the European Space Agency. NASA's Goddard Space Flight
Center in Greenbelt, Md., manages the telescope. The Space Telescope
Science Institute (STScI) in Baltimore, Md., conducts Hubble science
operations. STScI is operated by the Association of Universities for
Research in Astronomy, Inc., in Washington, D.C.
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