First images of a giant red star, 350 times larger than the sun

Credit: ESO

For the first time ever, a team of international researchers reveal detailed images of the surface of a star other than our sun. We now have images of a giant red star situated approximately 530 light years from our planet. 

In order to shed some light on the ways in which other interstellar systems and their respective planetary bodies have evolved, astronomers typically depend on what we have learned by studying our own solar system and the sun. In terms of stars, the sun in fact our is our main point of reference. The distance between other stars and earth and other obscuring factors have meant that until now, astronomers have never been able to conduct detailed studies on the surfaces of other stars. But for the first time ever, an international team of scientists have recently created the first detailed images of the surface of a giant red star.

As part of a study led by Claudia Paladini in the University of Brussels, the researchers used PIONEER imaging (Precision Integrated-Optics Imaging ExpeRiment) to observe a star known as Gr¹ Gruis. Situated 530 light years from the Earth in the Grue constellation, Gr¹ Gruis. is a giant red star similar to our sun, but 350 times larger and brighter.

Credits : Nature 553, 310–312 (18 January 2018)

Astronomers have for decades sought to know more about the convection properties and about the evolution of stars by studying these large red masses. These are stars which have exhausted their fuel (hydrogen) and that expand enormously before exploding. Unfortunately, it is difficult to study the convection properties of the majority of stars, because their surfaces are often obscured by dust.

Having obtained interferometric data on Gr¹ Gruis in September 2014, the team used image reconstruction software and algorithms to create images of the surface of the star. This allowed the team to determine the star’s convection patterns by studying its “granulations”. In fact, large granular spots that can be observed on the surface of the star indicate the top of a convective cell. It is the first time that such images have been created, and this represents a major step forward in terms of understanding how stars evolve.

This study is particularly significant in the sense that Gr¹ Gruis provides us with an image that could resemble that of our sun at the end of its life, in five billion years time, once all its hydrogen has burned out. At this stage, it will be big enough to engulf Mercury, Venus and possibly even the Earth.

You can find more details of this study in the scientific journal, Nature.