Astronomers capture first close-up image of star in a different galaxy

Astronomers achieved a groundbreaking milestone by capturing the first close-up image of the dying star WOH G64, located approximately 160,000 light-years away in the Large Magellanic Cloud, a satellite galaxy of the Milky Way. Using the Very Large Telescope Interferometer (VLTI) at the European Southern Observatory (ESO) in Chile, the research team, led by astrophysicist Keiichi Ohnaka from Universidad Andrés Bello in Chile, provided unprecedented insights into the final stages of a massive star's life.

"For the first time, we have succeeded in taking a zoomed-in image of a dying star in a galaxy outside our own Milky Way," Ohnaka said, according to ABC News. The achievement marks a significant advancement in astronomical observation, allowing scientists to study how stars behave in the final stages of their life cycles.

WOH G64 is classified as a red supergiant star and is approximately 2,000 times larger than the Sun, making it one of the largest known stars. The star is shedding its outer layers and is surrounded by an unexpected egg-shaped envelope of gas and dust as it approaches its end. This material is likely ejected as the star nears the end of its life cycle, offering valuable information about the processes that occur before a massive star explodes as a supernova.

The close-up image was captured using the GRAVITY instrument installed on the VLTI, which combines light from four telescopes to create highly detailed cosmic images. "Thanks to this image, we can create a better computer model of the star and study how it ejects material before its disappearance," Ohnaka explained.

Observations made in December 2020 allowed researchers to reconstruct a high-resolution image of WOH G64 in the near-infrared spectrum, showing the star surrounded by a glowing egg-shaped cocoon of gas and dust. This indicates material ejected by the star, which may be related to violent mass ejections before a supernova explosion. The elongated emission may be due to a bipolar outflow along the axis of the dust torus, or it could be caused by interaction with an unseen companion star.

The findings about WOH G64 were published in the journal Astronomy & Astrophysics, detailing the star's characteristics and significant mass loss during its red supergiant phase.

"We have detected that the star has undergone significant changes in the last 10 years, which gives us a rare opportunity to witness a star's life in real time," stated Professor Gerd Weigelt from the Max Planck Institute for Radio Astronomy in Germany.

"WOH G64 may never recover its original luminosity and may instead continue to fade slowly," Ohnaka commented. This behavior could confirm WOH G64's transition to a terminal state, offering a unique chance to study the final stages of a massive star's life.

WOH G64's immense size and extreme characteristics make it an especially interesting subject for study. If WOH G64 was placed at the center of our Solar System, it would extend to the orbit of Saturn, the sixth planet from the Sun. Despite its immense size, observing WOH G64 in fine detail was a challenge due to its distance and the complexity of studying stars in other galaxies.

The use of the VLTI and the GRAVITY instrument has overcome previous limitations in observing distant stars. The GRAVITY instrument provides unique resolution by combining light from four telescopes, enabling the team to detect minute details from distant objects.

As WOH G64 becomes fainter, it is increasingly difficult to take close-up images of it. However, planned updates to the VLTI's instrumentation, such as the future GRAVITY+, promise to improve the ability to capture even more detailed images of distant and faint stars.

The astronomers expect that WOH G64 will explode in a few thousand years—astronomically speaking, just a moment.

Understanding the progenitors to supernovae is important because of the role they play in the universe. Supernova explosions are essential to the creation of elements like carbon and oxygen, which are crucial for life. Such explosions forge heavy elements through nucleosynthesis and disperse them into space.

As more data is collected, WOH G64 could transform our understanding of supernovae and the fate of massive stars in neighboring galaxies.

ABC News, Die Zeit, Universe Today, Reuters, Le Figaro, and Deutsche Welle covered the new milestone, among others.

This article was written in collaboration with generative AI company Alchemiq