The star WOH G64, taken by the VLTI. Image: ESO/K Ohnaka et al
The images show the star WOH G64, which is roughly 2,000 times larger than our sun.
For the first time ever, astronomers have taken a close-up photograph of a dying star outside of our galaxy.
Announced yesterday (21 November) by astronomers at the European Southern Observatory (ESO), astronomers used the Very Large Telescope Interferometer (VLTI) to capture an impressively sharp image of star WOH G64 that has been known about for decades and is estimated to be around 2,000 times bigger than our solar system’s sun, making it a red supergiant.
The close-up photo of WOH G64, which lies some 160,000 light-years from Earth in the Large Magellanic Cloud, one of the small galaxies that orbits the Milky Way, along with observations by the research team, was published yesterday in the journal Astronomy & Astrophysics.
Lead author on the research paper, Dr Keiichi Ohnaka, an astrophysicist from Universidad Andrés Bello in Chile, explained: “We discovered an egg-shaped cocoon closely surrounding the star.
“We are excited because this may be related to the drastic ejection of material from the dying star before a supernova explosion.”
Ohnaka’s team has long been interested in WOH G64: back in 2005 and 2007, they used the ESO’s VLTI in Chile’s Atacama Desert to learn more about the star’s features, and carried on studying it in the years since.
To capture these new, detailed close-up images of the star, the research team had to wait for the development of one of the VLTI’s second-generation instruments. After comparing their new results with previous observations of WOH G64, the team were surprised to find that the star had become dimmer over the past decade.
“We have found that the star has been experiencing a significant change in the last 10 years, providing us with a rare opportunity to witness a star’s life in real time,” explained Prof Gerd Weigelt, astronomer at the Max Planck Institute for Radio Astronomy in Germany, who was a co-author of the study.
Weigelt, who has been studying WOH G64 since the 1990s, said the star is “one of the most extreme of its kind”, and said that any drastic change “may bring it closer to an explosive end”.
In their final stages, red supergiants like WOH G64 shed their outer layers of gas and dust in a process that can last thousands of years. However, the dust cocoon around the star is not the expected shape. The cocoon is stretched out, which surprised scientists, who expected a different shape based on previous observations and computer models.
The team believes that the cocoon’s egg-like shape could be explained by either the star’s shedding or by the influence of a yet-undiscovered companion star.
As the star becomes fainter, taking close-up pictures becoming increasingly difficult, even for the VLTI, though planned technological advances will hopefully change this, the ESO said.
“Similar follow-up observations with ESO instruments will be important for understanding what is going on in the star,” Ohnaka said.
This latest discovery follows last month’s announcement that astronomers using the VLTI discovered the existence of a new exoplanet orbiting Barnard’s star, the second closest stellar system to Earth.
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