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