EUROPE: Researchers from Yale and Harvard universities measured, for the first time, the pulse of red stars. The heart-pounding study analyzed how light in nearby galaxy is affected by the stellar pulse.
Giant stars like the Sun go through substantial changes over time. Giant stars grow brighter and expand enormously, causing them to swallow nearby planets. Towards the end of their lifetime, they start to throb which makes their light increase and decrease in brightness every several hundred days. Many stars in the Milky Way galaxy are in this phase of their lifetime.
People tend to think galaxies as static beacons, however, galaxies actually ‘shimmer’ because of all the pulsating giant stars in it, explained co-author and Sol Goldman Professor Pieter van Dokkum, who is also Yale’s Chair of Astronomy. It was only recently that the effects of these pulsating stars have on the light originating from distant galaxies have been measured and analyzed. The light of pulsating stars in distant galaxies is mixed with more light coming from stars that do not ‘pulsate’.
“We realized that these stars are so bright and their pulsations so strong that they are difficult to hide. We decided to see if the pulsations of these stars could be detected even if we could not separate their light from the sea of unchanging stars that are their neighbors,” said lead researcher and Harvard assistant professor Charlie Conroy.
Using three months’ worth of Galaxy M87 photos taken by the Hubble Space Telescope in 2006, the researchers found that 25 percent of the images have varying degrees of brightness, suggesting a ‘pulse’. The team found that the Galaxy M87’s stars has an average pulse of one beat every 270 days.
