Article Source: E&T
Data from Nasa telescopes has uncovered some of the mysteries behind blue supergiant stars, which have been shown to have relatively short lives before exploding as supernovae.
An international team of scientists led by KU Leuven in Belgium described blue giants as the “metal factories of the universe” and have been shown to produce all chemical elements beyond helium in the Periodic Table.
The team used data from the telescopes to show that the stars also shimmer and ripple in brightness due to the presence of waves on their surface, producing the twinkling effect sometimes seen in the night sky on Earth.
The discovery of waves in so many blue supergiant stars was a Eureka moment, said lead author Dr Dominic Bowman.
“The variability in these stars had been there all along, we only had to be patient and wait for modern space telescopes to observe them,” he said
“It is as if the rock-and-roll stars had been performing the whole time, but only now opened the doors of their concert hall because of Nasa space missions.
“We are now entering a golden age of asteroseismology of hot massive stars thanks to modern space telescopes. The discovery of these waves in blue supergiants allows us to study the progenitors of supernovae from a novel perspective.”
Modelling the interior of stars, the team predicted that gravity waves, like those we see in the ocean, could break at the surface of stars.
They also predicted the emergence of a second type of wave, similar to the seismic waves on Earth, which are generated from deep within the star.
As predicted, the waves originate in the stars’ deep interior and provide prospects for studying the supergiants using asteroseismology, similar to the study of earthquakes on Earth.
Publishing their findings in Nature Astronomy, the authors say that from observations of these waves, they can study properties of the stars that would be unobtainable from other astronomical techniques.
Co-author Dr Tamara Rogers said: “Throughout the universe, stars come in different shapes, sizes and colours. Some stars are like our Sun and live calmly for billions of years.
“Massive stars live significantly shorter and more active lives before they explode in what is called a supernova and expel their material into space.
“In line with our predictions, these latest observations have confirmed two types of wave which give us different information about the star.
“Those which break at the surface, similar to the waves breaking on the beach, and the standing wave that just keeps on going and is similar to the seismic waves on Earth.
“From these we can start to understand how the star is moving and rotating and the physics and chemistry of what is going on inside the deep interior, including the stellar core.
“Although we predicted these wave patterns, until now it was just that – a simulation of what might be going on. To actually see it and prove it is really quite an incredible moment for us.”