Exploring one of the largest stars in the Milky Way as it disappears from view | Urania

A team of astronomers recently made the first observations of a massive star that experienced a strange vanishing phenomenon. The images provide new evidence about the events taking place around this star, which is about 16,000 light-years away from Earth.

Images and observations, along with the use of intelligent algorithms developed by a team of scientists, indicate that a massive eruption occurred, causing a cloud of gas to be released from… R.W. Seavey, which blocks much of the light emanating from this star. Experts from Center for High-Resolution Angular Astronomy (CHARA). This new discovery was presented at the 243rd meeting of the American Astronomical Society in New Orleans published In the astronomical magazine.

In 2023, scientists were surprised by the observed phenomenon of the disappearance of a giant star, an example of a “cold star.” giant“- A star that has reached gigantic proportions and is approaching the end of its life. RW Cephei is so massive that if it occupied the Sun's place, its outer layers would extend beyond the orbit of Jupiter.

We made our first observations of CHARA in December 2022, just before the winter shutdown, but the results were so impressive that we decided to conduct additional observations when the star becomes available again. “It's a big problem,” said Georgia State University astronomer Narsireddy Anugu, who led an international team of scientists to take the first close-up images of RW Cephei to determine the source of its fading.

In 2022, astronomers Wolfgang Vollmann and Constantino Sigismondi announced that RW Cephei has weakened significantly over the past few years, which is unusual given the usual small variations in star brightness. By December 2022, RW Cephei's brightness had dropped to about a third of its normal brightness, an unprecedented decline. Scientists were interested in determining the reason for this significant decrease in the brightness of this star.

Despite its enormous size, RW Cephei is so distant that even with the largest conventional telescopes it looks like a point. Seeing the star up close requires the extraordinary capabilities of the CHARA Array telescope.

The CHARA Array is a six-telescope facility located at the historic Mount Wilson Observatory in California. The telescopes are placed on top of the mountain and work together as one giant telescope. By combining its light beams, the CHARA array has the ability to observe details of very small objects in the sky, about 30 times smaller than the largest conventional telescopes and smaller than a man on the moon as seen from Earth.

CHARA's observations showed that the star did not appear as round as expected, but producing a complete image required specialized computer software created by astronomy professor Fabian Baron of Georgia State University.

The final images show a star whose outer layers are shaking due to motions, causing fainter and brighter spots to appear on its surface. Furthermore, the star's appearance changed dramatically during the 10-month observation period, which coincided with it going from its faintest state to slowly returning to its previous brightness.

The final piece of the puzzle is additional observations of R.W. Cephei by Katherine Shepherd, a graduate student at Georgia State University, at Apache Point Observatory in New Mexico. Shepard used a special camera to capture RW Cephei's light from visible to infrared, and measurements showed that the decay was much greater in visible colors than in infrared. This is a warning sign that the starlight has been blocked by microscopic dust clouds, obscuring our view.

Together, the observations indicate that RW Cephei experienced a massive eruption that released a huge cloud of gas. As it moved away, the cloud cooled and created swarms of dust particles that effectively blocked much of the star's light. Now, as the cloud expands, we begin to see the star and its turbulent surroundings again.

CHARA director Douglas Gies believes this may be one of many large explosions that have rocked RW Cephei over the past century, and that such explosions will continue to play a role in the star's mass loss before falling.

This was special because the cloud shot toward the ground, so we were in the right place to witness the full effects of the disaster – said Jess.

development:
Agnieszka Novak

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Source: Georgia State University

Pictured: A false-color image of the star RW Cephei in December 2022 (left) and July 2023 (right). The patchy appearance is due to dust created by the massive ejection of material from the star. The star is huge, but so far away that it appears about a million times smaller than the full moon in the sky. Source: Chara