The James Webb Space Telescope continues to delight scientists and astronomy enthusiasts alike with a variety of new products. It has already shown us the most distant galaxy, one of the exoplanets and a whole family of beautiful spiral galaxies. And this time the telescope shows us the so-called Einstein ring which is almost perfectly shaped. The light from the distant galaxy that forms this ring has travelled 12 billion light-years through space before hitting the space telescope's mirror.
The galaxy in question now has the complicated and long name SPT-S J041839-4751.8. And unless another, more massive galaxy was located between it and Earth, we would never have been able to see it. However, the gravitational forces of the massive galaxy formed a gravitational lens that refracted and focused the light from SPT-S J041839-4751.8, visible as a bright ring. Naturally, we cannot see the original shape of the galaxy, but it can all be reconstructed by applying sophisticated mathematical processing to the ring image.
Note that the gravitational lens effect was described in Albert Einstein's theory of relativity, so the light focused by these lenses is called Einstein rings.
The Einstein ring effect is quite rare but it does occur because it requires that the distant space object, the object creating the gravitational lens and the telescope lens are strictly in line. If in this position there are any deviations, the ring of such a perfect form does not turn out, on the telescopes images are visible only its arc-shaped parts as in this case.
In fairness, we should note that the Einstein ring of the galaxy SPT-S J041839-4751.8 has already come into view of the James Webb telescope in early August this year. And an amateur astronomer had coloured it, as in this case, and published it online. But the previous image was of poor quality and could not be used to extract useful information about the distant galaxy.
The current image of Einstein's ring SPT-S J041839-4751.8 was taken by the James Webb Telescope's MIRI (Mid-Infrared Instrument) camera. Three different light filters were used, a red F1000W for wavelengths of 10 µm, a green F770W for wavelengths of 7.7 µm, and a blue F560W for wavelengths of 5.6 µm. And the same amateur astronomer with the nickname Spaceguy44 coloured the picture with the help of specialized program astropy and graphic editor GIMP.
