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RS Puppis (Cepheid Variable Star)


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RS Puppis
Cepheid Variable Star (ケフェイド変光星)

Spectral type: F8Iab
Variable type: Cepheid Variable

明るさ (Brightness)
7.0等級

星座 (Constellation)
とも座 (Pup) (Puppis)


距離 (Distance)
6,500光年 (6,500 light-years)

RS Puppis is a cepheid variable star located 6,500 light years from the Earth in the constellation Puppis.

RS Puppis (Cepheid Variable Star) : Picture

RS Puppis (Cepheid Variable Star)
RS Puppis (Cepheid Variable Star)
(C) NASA/ESA/Hubble Heritage (STScI/AURA)-Hubble/Europe Collab
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).

Nearby Cepheid Variable RS Pup
Nearby Cepheid Variable RS Pup
(C) Hubble Legacy Archive, NASA, ESA - Processing: Stephen Byrne
It is one of the most important stars in the sky. This is partly because, by coincidence, it is surrounded by a dazzling reflection nebula. 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 type 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 the 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. The above image was taken by the Hubble Space Telescope and digitally processed by a volunteer.

Echoes from RS Pup
Echoes from RS Pup
(C) Pierre Kervella (Obs. de Paris), Antoine Mérand (CHARA), et al., ESO
This dusty reflection nebula surrounds pulsating star RS Pup, some 10 times more massive than the Sun and on average 15,000 times more luminous. In fact, RS Pup is a Cepheid type 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 the nebula delayed in time, effectively a light echo. The otherwise overwhelming light from RS Pup itself is hidden behind the dark central stripe in the color image. Using new 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.

RS Puppis (Cepheid Variable Star) Nearby Cepheid Variable RS Pup
RS Puppis (Cepheid Variable Star)
(C) NASA/ESA
Nearby Cepheid Variable RS Pup
(C) Hubble Legacy Archive, NASA, ESA
Echoes from RS Pup
Echoes from RS Pup
(C) Pierre Kervella (Obs. de Paris), Antoine Mérand (CHARA), et al., ESO
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RS Puppis (Cepheid Variable Star) : Movie

Hubblecast 71: Visible echoes around RS Puppis
This episode of the Hubblecast explores striking new Hubble observations of a variable star known as RS Puppis. This star is growing brighter and dimmer as it pulsates over a period of five weeks. These pulsations have created a stunning example of a phenomenon known as a light echo, where light appears to reverberate through the foggy environment around the star.
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