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Credit & Copyright: NASA,
ESA,
Hubble Legacy Archive;
Processing & Copyright: Rogelio Bernal Andreo (DeepSkyColors.com)
Explanation:
Pulsating
RS Puppis,
the brightest star
in the image center,
is some ten times
more massive than our Sun and on average 15,000 times more luminous.
In fact, RS Pup is a Cepheid
variable star,
a class of stars whose
brightness
is used to estimate distances to nearby galaxies
as one of the first steps in establishing the
cosmic
distance scale.
As RS Pup
pulsates over a period of about 40 days,
its regular changes in brightness are also
seen along its
surrounding nebula delayed in time,
effectively a light
echo.
Using measurements of the time delay and
angular size of the nebula, the known
speed of light allows astronomers to geometrically
determine the distance to
RS Pup to be
6,500 light-years, with a remarkably small error of
plus or minus 90
light-years.
An impressive achievement for stellar astronomy, the
echo-measured
distance also more accurately establishes the true brightness of
RS Pup,
and by extension other Cepheid stars, improving the knowledge
of distances to galaxies beyond the Milky Way.
Processing & Copyright: Rogelio Bernal Andreo (DeepSkyColors.com)
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.
Based on Astronomy Picture
Of the Day
Publications with keywords: cepheid
Publications with words: cepheid
See also: