Astronomers at the Harvard-Smithsonian Center for Astrophysics have found for the first time a galaxy with a heartbeat and they have also measured its pulse by the effect that the older red stars have on the light of their surrounding galaxy. Conflicting to the belief, galaxies are said to be unsteady beacons, but they are sparkling due to the presence of giant, pulsating constituent stars.
Pieter van Dokkum, the Professor and chair of astronomy at Yale, explains that stars, like our Sun, undergo significant changes during later years of their life swelling up to enormous sizes.
A statement from CFA explained:
We tend to think of stars as stable and unchanging. However, late in life stars like the sun undergo a significant transformation. They become very bright and swell up to an enormous size, swallowing any planets that are within Earth’s distance from the sun. Near the end of their lifetime, they begin to pulsate, increasing and decreasing their brightness by a large amount every few hundred days. In our own Milky Way galaxy, many stars are known to be in this stage of life.
The Astronomers have spotted quite a few stars, but no research looked into the effects of stars on the light coming from more distant galaxies. “We realized that these stars are so bright and their pulsations so strong, that they are difficult to hide,” said Charlie Conroy, an assistant professor at Harvard University and astronomer at the Harvard-Smithsonian Center for Astrophysics (CfA), who led the research.
“We decided to see if the pulsations of these stars could be detected even if we couldn’t separate their light from the sea of unchanging stars that are their neighbors.” The research team analyzed images of the galaxy M87, in the constellation Virgo, captured by Hubble Space Telescope. And distant galaxies, too, have these sorts of variable stars. CFA said:
No one had considered the effects of these stars on the light coming from more distant galaxies. In distant galaxies, the light of each pulsating star is mixed in with the light of many more stars that are not varying in brightness.
Their analysis revealed that there were 25 percent of the pixels in the images of M87 that went up and down in brightness as if the galaxy had a heartbeat. Of course, even the older galaxies will continue to beat for a while longer. “Cardiac arrest is not expected until a trillion years from now,” van Dokkum said. “That’s a hundred times longer than the age of the universe.”Analysis of the Hubble data showed that the average pixel varies on a timescale of approximately 270 days. The regular up and down changes in brightness are reminiscent of a heartbeat.