A team of astronomers from Harvard and Yale have not only discovered a galaxy which they claim has a “heartbeat” of sorts, but they’ve actually managed to take its “pulse” by using three months worth of images obtained using the Hubble Space Telescope, according to a Yale statement.
According to Pieter van Dokkum, the Sol Goldman Professor and chair of astronomy at Yale and co-author of a new paper published in the journal Nature, this marks the first time that the impact of pulsating, older red stars on the light of their surrounding galaxy has been effectively measured by scientists.
Van Dokkum and his colleagues used a series of images Hubble captured of Messier 87 (M87), a supergiant elliptical galaxy located in the constellation Virgo. The images used during their study were obtained by the NASA/ESA space telescope over a three month span in 2006. They learned that one-fourth of the pixels in those images changed in brightness at regular intervals.
“We tend to think of the stars in the sky as unchanging and constant,” he told redOrbit via email. “We’ve known for centuries that some individual stars change their brightness, but most stars in the sky do not change perceptively on human time scales. What we found is that, paradoxically, if you take all the stars together, the combined light of all the stars does vary.”
Findings could radically change how we view distant galaxies
Each of those pixels, the professor explained, contains roughly one million stars. By carefully comparing each pixel, they found that that individual, bright, pulsating stars amongst the many unchanging stars were causing the overall galaxy’s light to pulsate every 270 days or so.
“This is because the rare, pulsating stars emit so much light that their pulsations can be measured even though each of them is surrounded by a million stars that don’t change,” van Dokkum said. Since our sun will go through this same phase when it nears the of its life cycle, the study offers a sneak-peak to the future that awaits our own solar system, he added.
“In this pulsating phase the Sun will swell to the size of the orbit of the Earth,” the professor explained. “That is, it will fill the entire sky and burn Earth to a crisp. If the pulsating stars in M87 have solar systems like our own, we are seeing them at the time when their inner planets have been destroyed – a somewhat unsettling thought!
“In practical terms (as in, ‘what do we do with these observations’), the strength of the ‘heartbeat’ should depend on a galaxy’s age: younger galaxies should show stronger pulsations than older galaxies,” he added. “The heartbeat therefore is a ‘clock’ telling us how old a galaxy’s stars are. We are planning to take the pulse of other galaxies to measure how old they are.”
Based on our knowledge of the stars in the Milky Way, van Dokkum said that this effect should be measurable, but he admitted that he and his colleagues were amazed when they discovered the increasingly and decreasingly bright pixels. The findings could change the way that scientists view distant galaxies like M87, which they now realize are not static, unchanging objects, but are instead continuously “shimmering” on timescales that can actually be observed.
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Feature Image: NASA/Hubble
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