Scientists have achieved the rare feat of getting a close-up shot of a star that is 1,60,000 light-years away from our galaxy and has a mass that is 2,000 times of the Sun. The first-ever, extreme close-up of the dying star reveals some crucial details about its activity and surrounding layers.
Known as WOH G64, the massive star has been imaged with remarkable sharpness by the European Southern Observatory’s Very Large Telescope Interferometer (ESO’s VLTI). The latest image reveals that the star emanates dust and gas, a sign that it is in its last stages before becoming a supernova triggered by a powerful explosion towards the end of a star’s life.
Talking about the new feat, Keiichi Ohnaka, an astrophysicist from Universidad Andres Bello in Chile, said, “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, who led the study, said that his team discovered ‘an egg-shaped cocoon’ closely surrounding the star.
The study with observations by Ohnaka’s team, has been published in Astronomy and Astrophysics. The latest observation is a milestone; while astronomers have been taking detailed images of stars in the galaxy revealing their properties, there are many other stars that exist in other galaxies far, far away. Observing one such star in great detail is a big step forward.
What is WOH G64?
The WOH 64 is a giant star that dwells in the Large Magellanic Cloud, a dwarf or satellite galaxy that orbits our Milky Way, which also happens to be one of the closest galaxies to us. It was discovered in the 1970s by Bengt Westerlunds, Olander, and Hedin. Incidentally, the WOH in its name is the acronym for the names of its three discoverers. The star is believed to be around 1,60,000 light years away from Earth. The star is classified as a red supergiant owing to its size, which is roughly 2,000 times that of the Sun.
Ohnaka’s team has been closely observing the giant star for years. In 2005 and 2007, the team reportedly used ESO’s VLTI in the Atacama Desert of Chile to ascertain the features of the star. Since then, they have been studying the star. But, they were unable to obtain an actual image of it until now.
To get an accurate image, the team had to wait for the development of GRAVITY, a set of VLTI’s second-generation instruments. The team compared the new results with previous observations of the star to find that it has dimmed over the past decade.
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George Weigelt, an astronomy professor at the Max Planck Institute for Radio Astronomy in Germany who also co-authored the study, said that the star has been going through significant changes in the last 10 years.
Red supergiants like WOH G64 shed their outer layers, which are mainly gas and dust, in the final stages of their lifecycles. This process can continue for thousands of years. “This star is one of the most extreme of its kind, and any drastic change may bring it closer to an explosive end,” said another co-author, Jacco van Loon, Keele Observatory Director at Keele University, UK. According to the team, the materials that are being shed could be responsible for the dimming of the star and the unusual shape of the dust cocoon around it.
With stars becoming fainter, getting close-up pictures would be difficult, even for the highly advanced VLTI. However, upcoming upgrades to VLTI, such as the GRAVITY+, are likely to change this and ensure more detailed images of distant and elusive stars.
