Space is actually full of dust, which can impact the evolution of stars and even of whole galaxies

The following picture is an artistic creation by the twelve-year-old Polish student Matylda Soszynska, who won the first prize in an artistic/scientific competition for children during the conference “GAPS 2021-unsolved problems in red Giants And suPergiantS”, held from the 14th to the 18th of June.

What Matylda wanted to show was the efficient production of dust by a very old and evolved star, following the cooling of the ejected plasma. Space is actually full of dust, just think of the black dusty clouds that prevent us from having a full and direct vision of the center of the Milky Way, or the well-known dark strip that runs through the Sombrero Galaxy. Dust is primarily generated by stars of similar mass to our Sun, but much redder and in a much more advanced evolutionary stage, known as AGB stars. In particular, these stars are characterized by a very rapid mass-loss, which will often cause the formation of a spectacular planetary nebula, with the former core of the star, now stripped of any outer layer, located at the center and known as a white dwarf.

Credits: Matylda Soszynska

There are also other stars, which very old as well but much more massive, that are real galactic “dust factories”. Just think about the red supergiant Betelgeuse, whose “great dimming” from November 2019 to February 2020 marked an unprecedented decrease in brightness, of almost 2 magnitudes in the V band. Indeed, it seems that one of the main causes (in addition to the possible formation of gigantic starspots, with a total extension equal to 50% of the surface of the star) of that surprising phenomenon was a large expulsion of newly formed dust along the line of sight in the direction of our planet, which would have thus obscured the supergiant (probably in a similar way to what is shown in the image) causing its apparent diming.

References:

Montargès, M., Cannon, E., Lagadec, E. et al. Nature 594, 365–368 (2021).

Dharmawardena et al.; The Astrophysical Journal Letters, 897:L9 (7pp), 2020 July 1

Nanni, Ambra; MNRAS 482, 4726–4732 (2019)

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