Research on red giants could help astronomers predict the universe’s most powerful explosions like supernovas.
The red giants (RSG) are the largest stars in the universe by volume, but their masses are low or medium (between 0.5 and 9 solar masses). The reason is that these objects are in the later stages of stellar evolution, causing matter to compress in the nucleus, as the atmosphere expands and thins.
When the RSGs collapsed, they produced terrible explosions called Type II supernovae – events that can be observed hundreds of light years away with a telescope. Our sun in the distant future of about 7.59 billion years is also expected to become a red giant. At that time, it was so large that it “swallowed” the orbits of all the planets within the solar system.
To study, model and predict when RSGs will collapse, astronomers need to measure their temperatures. However, current stellar temperature measurement methods give inaccurate results for RSG due to its complex atmospheric structure.
“To measure the temperature of red giants, we need to find visible spectral properties that are unaffected by their upper atmosphere. Chemical signs such as ‘absorption lines’ are the ideal candidate, but there are none. way of revealing the temperature of However, by examining the ratios of the two different absorption lines with respect to iron, we found that it could provide information about the temperature of the RSG, ”said the lead author of the Daisuke Taniguchi study from the University of Tokyo.
According to a report published in the Monthly Notices of the Royal Astronomical Society, Taniguchi and his colleagues used a tool called WINERED to obtain the spectral properties of certain red giants. Based on this data, they calculate iron absorption lines and estimate the temperature of target stars. Finally, they used precise distance measurements from the European Space Agency’s Gaia Space Observatory to establish a consistent relationship between the distance, brightness and temperature of the RSG.
“We still have a lot to learn about supernovae and related objects and phenomena. This new method of measuring the temperature of the red giant will help astronomers fill in some gaps,” Taniguchi said.
The team adds that Betelgeuse – the 12th brightest red giant star in the night sky – could collapse to become a supernova in the near future as it quickly faded away over the past two years. “It would be great if we could predict when the celestial body would collapse into a supernova. I hope new temperature measurement techniques will help in this effort and beyond,” Taniguchi added.
