The Hubble telescope has observed a star that pulsates while growing brighter and dimmer.
The alternating pulsations caused what is called a "light echo," this is where "light appears to reverberate through the murky environment around the star," a Hubble news release reported via Azooptics.
Stars tend to slowly and steadily consume fuel throughout their lives. Once they've used up all of their hydrogen sustenance some become angry pulsating stars. These unstable stars "expand and shrink" over up to several weeks, their light fluctuates as well.
The star observed by Hubble, dubbed RS Puppis, which is a variable star called a Cepheid variable. The star is believed to vary in brightness in periods of about 40 days for each stage of fluctuation; this is considered to be relatively long.
The star is out of the ordinary because it is covered in a thick gas and dust cloud called a nebula. Despite the protective haze, Hubble was able to observe RS Puppis for five weeks back in 2010.
The team was even able to capture a time-lapse video of the object's pulsation. The video (made up of a number of snap shots) captured a "movement that was determined to the "light echo" phenomenon.
The dust around the star helped the phenomenon to appear in the footage with "stunning clarity." As the star "expands and brightens" movement is reflected in far-off dust shells around RS Puppis.
This light has to travel further to reach Earth, so it arrives after the light reflected directly from the star.
"This is analogous to sound bouncing off surrounding objects, causing the listener to hear an audible echo," the news release reported.
The video is rewarding in that it is visually stunning; but studying RS Puppis comes with a number of rewards.
"The period of their pulsations is known to be directly connected to their intrinsic brightness, a property that allows astronomers to use them as cosmic distance markers. A few years ago, astronomers used the light echo around RS Puppis to measure its distance from us, obtaining the most accurate measurement of a Cepheid's distance (eso0805). Studying stars like RS Puppis helps us to measure and understand the vast scale of the Universe," the news release reported.
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