Using ESOâs Very Large Telescope (VLT), astronomers have captured the unprecedented dimming of Betelgeuse, a red supergiant star in the constellation of Orion. The stunning new images of the starâs surface show not only the fading red supergiant, but also how its apparent shape is changing.
Betelgeuse has been a beacon in the night sky for stellar observers, but it began to dim late last year. At the time of writing, Betelgeuse is at about 36Â percent of its normal brightness, a change noticeable even to the naked eye. Astronomy enthusiasts and scientists alike were excitedly hoping to find out more about this unprecedented dimming.
A team led by Miguel MontargÃ¨s, an astronomer at KU Leuven in Belgium, has been observing the star with ESO’s Very Large Telescope since December, aiming to understand why itâs becoming fainter. Among the first observations to come out of their campaign is a stunning new image of Betelgeuseâs surface, taken late last year with the SPHERE instrument.
The team also happened to observe the star with SPHERE in January 2019, before it began to dim, giving us a before-and-after picture of Betelgeuse. Taken in visible light, the images highlight the changes occurring to the star both in brightness and in apparent shape.
Many astronomy enthusiasts wondered if Betelgeuseâs dimming meant it was about to explode. Like all red supergiants, Betelgeuse will one day go supernova, but astronomers donât think this is happening now. They have other hypotheses to explain what exactly is causing the shift in shape and brightness seen in the SPHERE images. MontargÃ¨s said:
âThe two scenarios we are working on are a cooling of the surface due to exceptional stellar activity or dust ejection towards us. Of course, our knowledge of red supergiants remains incomplete, and this is still a work in progress, so a surprise can still happen.â
MontargÃ¨s and his team needed the VLT at Cerro Paranal in Chile to study the star, which is over 700 light-years away, and gather clues on its dimming. MontargÃ¨s said:
âESO’s Paranal Observatory is one of few facilities capable of imaging the surface of Betelgeuse.â
Instruments on ESOâs VLT allow observations from the visible to the mid-infrared, meaning astronomers can see both the surface of Betelgeuse and the material around it. MontargÃ¨s added:
âThis is the only way we can understand what is happening to the star.â
Another new image, obtained with the VISIR instrument on the VLT, shows the infrared light being emitted by the dust surrounding Betelgeuse in December 2019. These observations were made by a team led by Pierre Kervella from the Observatory of Paris in France who explained that the wavelength of the image is similar to that detected by heat cameras.
The clouds of dust, which resemble flames in the VISIR image, are formed when the star sheds its material back into space.Â Emily Cannon, a Ph.D. student at KU Leuven working with SPHERE images of red supergiants, said:
âThe phrase âwe are all made of stardustâ is one we hear a lot in popular astronomy, but where exactly does this dust come from?â
âOver their lifetimes, red supergiants like Betelgeuse create and eject vast amounts of material even before they explode as supernovae. Modern technology has enabled us to study these objects, hundreds of light-years away, in unprecedented detail giving us the opportunity to unravel the mystery of what triggers their mass loss.â
Provided by: European Southern Observatory (ESO)Â [Note: Materials may be edited for content and length.]