The mystery of the ‘Great Dimming of Betelgeuse’ solved - Tech Explorist

When Betelgeuse, a bright orange star in the constellation of Orion, became visibly darker in late 2019 and early 2020, the astronomy community was puzzled.

The team continued observing the Betelgeuse star during its Great Dimming, capturing two other never-before-seen images in January 2020 and March 2020.

In their new study, published today in Nature, the team revealed that the mysterious dimming was caused by a dusty veil shading the star, which in turn was the result of a drop in temperature on Betelgeuse’s stellar surface.

The team used the Spectro-Polarimetric High-contrast Exoplanet REsearch (SPHERE) instrument on ESO’s VLT to directly image the surface of Betelgeuse, alongside data from the GRAVITY instrument on ESO’s Very Large Telescope Interferometer (VLTI), to monitor the star throughout the dimming.

The telescopes, located at ESO’s Paranal Observatory in Chile’s Atacama Desert, were a “vital diagnostic tool in uncovering the cause of this dimming event,” says Cannon. “We were able to observe the star not just as a point but could resolve the details of its surface and monitor it throughout the event,” Montargès adds.

Montargès and Cannon are looking forward to the future of astronomy, in particular, what ESO’s Extremely Large Telescope (ELT) will bring to their study of Betelgeuse, a red supergiant star. “With the ability to reach unparalleled spatial resolutions, the ELT will enable us to image Betelgeuse in remarkable detail directly,” says Cannon. “It will also significantly expand the sample of red supergiants for which we can resolve the surface through direct imaging, further helping us to unravel the mysteries behind the winds of these massive stars.”.