In 2017, astronomers from the Universidad Católica del Norte, in Chile, managed to reproduce the best photo of the surface of a star other than the Sun. Through their work, they were able to achieve a resolution never before achieved for an image of a star. The star in question, which posed for the astronomers, is Antares and is the brightest star in the constellation of Scorpio. Looking at the photo, you might think that they forgot to focus, but in fact, it is the first time that such high quality has been achieved. It’s not easy to photograph a star about 600 light years away from us!
The best photo of a star other than the Sun: How to study Antares
Taking such a clear picture of a star like Antares is not just a good result from an aesthetic point of view. In fact, thanks to this photo, astronomers have been able to study various behaviours of the star and discover interesting phenomena. The computer-reconstructed photo depicts the surface and atmosphere of Antares and thus provides the first two-dimensional velocity map of the atmosphere of a star other than the Sun. From the various images collected, the team of astronomers calculated the difference in the speed of atmospheric gas at different points on the star and the average speed on the star. A result never before achieved, thanks to the best photo of a star other than the Sun.
New discoveries thanks to the best photo of the surface and atmosphere of a star other than the Sun
The one taken at Antares is not only the best picture ever taken of a star other than the Sun. In fact, from this image, experts have found unexpected turbulence. More precisely, they were able to identify turbulent low-density gas much further away than expected. An observation that led to the conclusion that the motion of atmospheric gas cannot be due to convection. Convection refers to large-scale particle motion, whereby energy is transferred from the core to the outer layers of the atmosphere. This process, therefore, does not occur on red supergiants such as Antares, which are governed by a different but as yet unknown process.
In the future, this observational technique may be applied to different types of stars to study their surface and atmosphere in unprecedented detail. This type of study has so far been limited to the Sun. Our work takes stellar astrophysics to a new level and opens a whole new window to stargazing.– Keiichi Ohnaka, first author of the article on the Antares photo
The telescope for the best photo of a star other than the Sun
The best picture of the surface and atmosphere of a star other than the Sun has been taken with the VLTI (Very Large Telescope Interferometer). The VLTI is an ESO (European Southern Observatory) telescope and works by combining light beams from several telescopes. In this way, it can be likened to a single large virtual telescope with a mirror up to 200 metres in diameter. To acquire the measurements of Antares, the VLTI used three auxiliary AT telescopes and the AMBER instrument. The four AT telescopes (Auxiliary Telescopes) have a diameter of 1.8 m and feed light into the VLTI’s interferometer. The AMBER instrument (Astronomical Multi-BEam combineR), on the other hand, is the near-infrared spectro-interferometer instrument. It works in the bands between 1.6 and 2.4 μm and has been designed to coherently combine three telescopic beams.
The brightest star in the constellation of Scorpio: Antares
Antares is the star of this fantastic photo: the most beautiful photo ever taken of a star other than the Sun. Antares is the brightest star in the constellation of Scorpio and the brightest in the entire celestial vault. Besides being among the brightest, it is among the largest known: its radius is about 850 times that of the Sun. The large volume is precisely a characteristic of red supergiant stars, as Antares is. Red supergiants are stars that are near the end of their lives and will astronomically explode into supernovas in a short time. They are characterised by very low temperatures that give them their characteristic orange-red colour..