Astronomers at the Atacama Large Millimeter/submillimeter Array (ALMA) observatory have observed something very surprising for the very first time: a weird tridimensional spiral structure inside of a dying star, one that is just like our very own Sun.
Is this the last thing that the human race will ever see (if we manage to survive five billion years)?
That question is part of what ALMA—the largest astronomical project in existence—is trying to uncover from the Chajnantor plateau, in the Atacama Desert, Chile. According to Shazrene Mohamed, co-author of the study on this weird star, "ALMA is giving us new insight into what's happening in these stars [coincidentally, alma means soul in Spanish] and what might happen to the Sun in a few billion years from now."
However, we will probably not see the 3D spiral structure of R Sculptoris when the Sun dies. According to the study published in the journal Nature, the reason for this surprising structure may be an unseen companion object, a smaller star orbiting around this red giant. This companion body, however, hasn't been observed yet and this theory hasn't been confirmed.
But what is even more important than knowing how the Sun is going to end 5 billion years from now is the information that this spiral tell us about where we come from.
The research team used half of the 66 high precision antennas that compose the revolutionary ALMA telescope to get right inside the guts of this red giant, located 1,000 light years away in the constellation of Sculptor. R Sculptoris is big and near enough to be observed with an amateur telescope. In fact, you can even track "its slow variations in brightness"—its heart pulsing as it dies.
The astronomers were surprised by the spiral found inside R Sculptoris' external shell for two reasons. One, because this structure allows them to follow how the star ejected its material as it expanded from something like the Sun to its current giant red form. According to the lead author of the paper—Matthias Maercker, from the Argelander Institute for Astronomy, University of Bonn, Germany—"we've seen shells around this kind of star before, but this is the first time we've ever seen a spiral of material coming out from a star, together with a surrounding shell."
To understand this, the deformations caused by the companion star give them something similar to a map that allows them to go back in time. It's like reading into the rings of a tree, looking for years that were better or worse for its growth. According to the study "the new observations of R Sculptoris show that it suffered a thermal pulse event about 1800 years ago that lasted for about 200 years."
The other surprising finding is that this star has ejected far more material than any model predicted before for these kind of stars.
This is important to understand how we got here in the first place. Like the Sun, R Sculptoris didn't have enough mass to go supernova. Instead, it started to grow, sputtering heavy materials out into space. According to Maercker, these heavy elements are the raw materials that make future stars and planets like ours, the very basic physical building blocks that, at least in one occasion, have combined to create a planet capable of harboring life:
In the near future, observations of stars like R Sculptoris with ALMA will help us to understand how the elements we are made up of reached places like the Earth.
The video above shows the internal structure of the star, taken by ALMA in a way similar to how a CT scanner works, showing slices through data taken at a slightly different frequency. The "clear spiral structure in the inner material that it best seen about half-way through the video sequence," according to the scientists. [ALMA Observatory]