Friday, February 4, 2022

A red giant loses its “skin"

This ghostly image shows a distant pulsating red giant star, called R Sculptoris. Situated 1200 light-years away in the constellation Sculptor, R Sculptoris is a carbon-rich star that belongs to the asymptotic giant branch (AGB), meaning it is approaching the end of its life. At this stage, low and intermediate-mass stars cool, creating extensive atmospheres and losing much of their mass — they are therefore on their way to becoming planetary nebulae.

Although the basic process of this loss of mass is well understood, astronomers are still investigating how this process starts near the surface of the star. The amount of mass lost by the star actually has important implications for its stellar evolution, altering its future and giving rise to different types of planetary nebulae. AGB stars end their lives as planetary nebulae, producing large numbers of elements — including 50% of elements heavier than iron — which are thus released into the Universe and used later to create new stars, planets, moons and eventually the building blocks. constituents of life.

A particularly intriguing feature of R Sculptoris is its dominant bright spot, which appears to be two or three times brighter than the other regions. The astronomers who obtained this image, using ESO 's Very Large Telescope Interferometer (VLTI), have concluded that R Sculptoris is surrounded by giant 'nodes' of stardust being lost by the star. This bright spot is, in fact, a region around the star with little or no dust, which allows us to look deeper into its surface. This image captures an extremely small area of ​​the sky: about 20 x 20 milliarcseconds. In terms of comparison, Jupiter has an angular size of approximately 40 seconds of arc.

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