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An international team of astronomers produced the first detailed images of the surface of a giant star outside the solar system, which it believes reveals what the Sun will look like in the future.
The State University of Georgia, in the United States, reported that it is “an almost circular shape, with an atmosphere free of dust and with complex areas of moving material, known as convective cells or granules.”
The name of the star is π1Gruis and was observed, for the first time directly, thanks to the Very Large Telescope of the European Southern Observatory (ESO, for its acronym in English: European Southern Observatory ), located in Chile.
“A star evolved in the last major phase of life, π1Gruis is 350 times larger than the Sun and resembles what our Sun will become at the end of its life in 5 billion years,” the university said in a statement.
“Studying this star gives scientists an idea about the activity, characteristics and appearance of the Sun in the future.”
When the Sun swells
The findings of the group of astronomers, led by ESO researcher Claudia Paladini, were published in the specialized journal Nature .
According to ESO, which is the main intergovernmental organization dedicated to astronomy, ” in about 5 billion years, our Sun will swell to become a similar red giant star.”
π1Gruis is in the constellation of Grus and is located at 530 light years from Earth .
It also has a very peculiar characteristic, it is: “several thousand times brighter” than the Sun.
“This is the first time we have an unequivocal image with that level of detail of a giant star like this,” said Fabien Baron, one of the study’s authors and an assistant professor in the Department of Physics and Astronomy at the State University of Georgia.
View in Chile
The image was obtained thanks to the Pionier instrument -which is made up of four telescopes- that SEO has in its observatory in Chile.
“The reason is that there is a limit in the details that we can see depending on the size of the telescope used for the observations, for this study, we used an interferometer.” The light from several telescopes combined to overcome the limitations of each telescope, thus achieving a resolution equivalent to that of a much larger telescope , “said the researcher.
The university said that, after observing the star with Pionier, in Chile in September 2014, Baron “used interferometric data, image reconstruction software and algorithms to compose images of the star’s surface “.
ESO explained that the researchers discovered that “this red giant has a few convective cells or granules, and that one of them has a size of about 120 million kilometers (about a quarter of the diameter of the star)”.
The peculiarity of this “old star”, as it is described by the organization made up of 16 countries, is that the dust around it does not prevent appreciating it.
“When we look at the surfaces – known as photospheres – of many giant stars, we see them obscured by dust, which makes observations difficult, but in the case of π1Gruis, although there is dust away from the star, its presence does not have a significant effect on new infrared observations, “ESO said.
“When, a long time ago, π1 Gruis ran out of hydrogen to burn, this old star left behind the first stage of its nuclear fusion program, contracted as it ran out of fuel, causing the temperature to rise more than 100 million of degrees “.
Those extremely high temperatures caused its core to intensely heat up and expel its outer layers “causing it to grow to a size hundreds of times larger than its original size”.
“Until now, they have never obtained detailed images of the surface of one of these stars,” ESO said.