Astronomers have discovered that a giant star called R Sculptoris is surrounded by giant ‘clumps’ of stellar dust that are peeling away from the shedding star.
This image shows a distant and pulsating giant star known as R Sculptoris. Image credit: M. Wittkowski / ESO.
R Sculptoris, also known HD 8879 and IRAS 01246-3248, is located in the constellation of Sculptor, about 1,500 light-years away from Earth.
“R Sculptoris is something known as a carbon-rich asymptotic giant branch (AGB) star, meaning that it is nearing the end of its life,” explained ESO astronomer Markus Wittkowski and colleagues.
“At this stage, low- and intermediate-mass stars cool off, create extended atmospheres, and lose a lot of their mass — they are on their way to becoming spectacular planetary nebulae.”
“While the basics of this mass-loss process are understood, astronomers are still investigating how it begins near the surface of the star.”
“The amount of mass lost by a star actually has huge implications for its stellar evolution, altering its future, and leading to different types of planetary nebulae,” they said.
“As AGB stars end their lives as planetary nebulae, they produce a vast range of elements — including 50% of elements heavier than iron — which are then released into the Universe and used to make new stars, planets, moons, and eventually the building blocks of life.”
The astronomers analyzed several days of interferometric observations captured by two instruments on ESO’s Very Large Telescope Interferometer (VLTI) between October 2012 and December 2015.
The VLTI observations revealed a complex structure and a dominant bright spot within R Sculptoris’ stellar disk.
“The detected complex structure is most likely caused by giant convection cells, resulting in large-scale shock fronts, and their effects on clumpy molecule and dust formation seen against the photosphere at distances of 2-3 stellar radii,” Dr. Wittkowski and co-authors said.
“The bright spot is, in fact, a region around the star with little to no dust, allowing us to look deeper into the stellar surface.”
The team’s findings were published recently in the journal Astronomy & Astrophysics (arXiv.org preprint).
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M. Wittkowski et al. 2017. Aperture synthesis imaging of the carbon AGB star R Sculptoris. Detection of a complex structure and a dominating spot on the stellar disk. A&A 601, A3; doi: 10.1051/0004-6361/201630214
