The gossamer veil of reflective dust surrounding the star RS Puppis reflects its flickering light in a fantastic display.

Variable star RS Puppis

The variable star RS Puppis is the only Cepheid variable star enshrouded in a gossamer veil of dust. The dust reflects the star's light, providing a "light echo."

NASA / ESA / Hubble Heritage Team (STScI/AURA)

The star RS Puppis sparkles in the Southern Hemisphere, brightening by a factor of five roughly every six weeks. It’s a supergiant star, 200 times the size of the Sun and 15,000 times as luminous.

And more importantly, it’s a Cepheid variable, a “standard candle” whose pulsations are inextricably linked to its luminosity and therefore to its distance. So astronomers were delighted to discover some time ago that the star is enshrouded in a veil of reflective dust, which is unusual for Cepheids. The gossamer nebula may be a remnant of the cloud in which the star formed.

The dust echoes the varying starlight in a fascinating display that’s not only a mesmerizing view — it also gives astronomers a method with which to calibrate the relation between luminosity and distance in all Cepheid variables. One estimate by Pierre Kervella (Observatory of Paris, France) and colleagues put the star between 6,405 and 6,588 light-years away.

That estimate continues to be refined because it's not clear where the reflecting dust lies relative to the star, says Howard Bond (Space Telescope Science Institute and Pennsylvania State University) — if the dust doesn't lie in the plane of the star, the distance measurement could be off. Bond, Kervella, and others are busy analyzing the images Hubble captured, including the image above and the sequence below, to make a better measurement.

Take a gander, it's pretty cool!


Image of evi


December 25, 2013 at 2:38 am

(So is this the same star or adifferent one thats..) I live in florence montana and everyday an hour or two b4 it gets dark like 5pm there is this amazingly huge white star west over the mountains and then whenever I go to look at it a few hours later its gone outta my sight and its not flickery like other stars or multi-colored its just white like a car headlight in the sky just wanted to know if this is the same star please or what is it if not?

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December 25, 2013 at 8:26 am

No Evi, the star in this news story, RS Puppis, is not the bright object we are seeing in the west in the evening. As Monica Young stated in her first sentence in her article, this star is visible only in the Southern Hemisphere. In fact, something you noticed about “the star” you are asking about tells us that what you described isn’t really a star at all. Stars often twinkle, but planets don’t, so the fact that it’s both bright and “not flickery” means that what you are talking about must be a planet. Try finding out which one it is by going into the “Observing” page in this website and look under “Planets”. I bet you can figure it out yourself Evi.

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December 25, 2013 at 11:02 am

My eyes were both sensitive and my vision was sharp and acute growing up, and one bright clear day, I stood watching the progress of an jet airliner [1956,or 57] leaving it's vapor trail across a deep blue near purple-blue cloudless sky you now never see in the northern hemisphere, except when you stand on ground over 14,000 ft.

As I watched, I saw what appeared to be something dropped from the jet aircraft, a light whitish colored object, appearing to fall from the aircraft as the contrail drifted away across it. Finally, realizing it was not falling and with the Jet continuing to fly toward LA, I realized it might be a high altitude balloon, but even my sharp 10 year-old eyes could not discern a balloon's tear-drop shape if it were a high altitude package one often saw from my location in Colorado, balloons launched in Texas, New Mexico or elsewhere.

So keeping my eyes on the object the jet dropped or occulted, I marched across the yard to a point near a two story grain storage barn, and marked my position by kicking a mark in the dirt. I marked the ground where I could see the object at the barn's peaked apex. I ran and got my 1-inch diameter collapsible refractor telescope with tripod,. set it on the ground where marked, Yep, Venus!!!! West of the Sun. Since then I have occasionally tested my eyesight locating Venus thousands of times in broad bright daylight.

Use SKY and Telescopes sky guide! My first daylight observation of Venus showed me Venus about half-lit, like last quarter moon in shape. You can do this with naked eye too. If you use binoculars's don't look too close to the Sun.

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Anthony Barreiro

December 27, 2013 at 1:10 pm

That is a very cool video! To see the waxing and waning light of a cepheid variable reflected by its natal dust cloud is breathtaking! I enjoy seeing the changing brightness of Delta Cephei, but it never looks like that.

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Image of Dieter


December 30, 2013 at 5:43 am

@Evi: as Bruce already stated, the very bright object that you see in the evening towards the west is a planet, it is the planet Venus, which circles the Sun within the orbit of the Earth and thus never gets very far away from the Sun in the sky. You can currently see it setting after the Sun as the "evening star". It will overtake the Earth in its orbit in the coming months and move to the other side of the Sun, so it will rise earlier than the Sun in the morning and become a "morning star". Venus is the next brightest natural object in the sky after the Sun and Moon (the man-made ISS space station and Iridium satellites can be brighter). Venus is so bright because it is completely shrouded in shiny white clouds, it gets twice as much light from the Sun as the Earth because it is closer to the Sun) and it is relatively close to the Earth currently.

If you turn 180° to the east, you can see another bright object in the evening, which is the planet Jupiter. It is both far from the Sun and far from the Earth, but quite large, about 12 Earth diameters, while Venus is just a bit smaller than our own planet. If you own a pair of binoculars, point it at Jupiter and you will certainly be amazed by its little company.

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