T. Schirmer, T. Khouri; / THAT; SOUL; ESO/NAOJ/NRAO
The image captured in polarized visible light with the VLT/SPHERE. In the center, in yellow and orange, we see the ALMA image that shows the surface of the star
New observations by researchers at Chalmers University of Technology, in Sweden, cast doubt on a long-accepted idea: that the light from dying stars pushes molecules associated with the so-called “seeds of life”, such as oxygen and carbon, across space throughout the cosmos.
A new study concludes that the strength starlight driverre of the dust released by red giant stars is insufficient to allow these molecules to escape the gravitational pull of the host star.
This result, presented in a recently published Astronomy and Astrophysicsis a new astronomical enigma that the scientific community now suddenly has to solve.
“We thought we had a good idea of how the process worked,” he explains. Trueastronomer from Chalmers and one of the coordinators of the work, cited by . “After all, we were mistaken. For us as scientists, this is the most exciting result.”
Although researchers have not yet found irrefutable proof of life beyond Earth, there is broad consensus that the molecules and elements necessary for terrestrial biological life to exist and thrive have been generated. inside the stars.
Over the past few decades, most scientists have been relatively confident that these molecules and other essential life-supporting elements are propelled by stellar winds, “hitchhiking” dust grainsinto the depths of the cosmos, where they could seed the formation of new planets and, potentially, life — the so-called ““.
Described as the So’s “colder cousins”l, red giants lose enormous amounts of matter through the phenomenon of stellar winds.
While this mechanism is likely crucial to the hypothesis of the spread of life-associated matter throughout the cosmos, the team emphasizes that the exact process that drives these winds is “has remained uncertain”.
To better understand the phenomenon, scientists at UT Chalmers focused on a red giant, the R Doradusjust 180 light years away from Earth, in the constellation of Dorado.
Although this dying star once had a mass relatively similar to that of the Sun, it currently has loses, on average, about 1/3 of the mass of Earth per decade.
The team states that this behavior is characteristic of stars in the industry “asymptotic giant” (AGB), which “lose their outer layers into interstellar space” through stellar winds composed of gas and dust. When our Sun reaches the end of its life, billions of years from now, it is expected that evolve into this category of stars in the terminal phase.
“AR Doradus is a favorite target of ours. It’s bright, it’s close and it’s typical of the most common type of red giant,” explained Khouri.
The first stage of the work involved measure starlight reflected by the tiny grains of dust surrounding R Doradus.
Given the tiny amount of light that the team was looking to detect, the researchers gained access to the SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) instrument, installed on the European Space Agency’s (ESA) Very Large Telescope (VLT), in Chile.
“With the best telescopes in the worldwe can now make detailed observations of the closest giants,” said Khouri.
After analyzing polarized light at different wavelengths, researchers came to several conclusions.
SPHERE identified, for example, light signatures compatible with the presence of dust grains around the star. The data further indicated that the size and composition of these grains were “consistent with common forms of stardust”, including silicates and alumina.
The team then combined the data obtained from the telescope with computer simulations designed to model the interaction between stellar dust and the light emitted by the star.
These comparisons constituted the first rigorous tests to confirm whether the dust grains that contain molecules associated with the “seeds of life” feel a “strong enough push” from starlight, explains astronomer Thiébaut Schirmerone of the study’s co-authors.
After comparing the data, the researchers concluded that the pressure exerted by the star’s light “not enough” to push the dust grains to interstellar space.
The reason is in the size: Most of the grains around R Doradus measure only about a ten-thousandth of a millimeter. According to the team, this makes them too small for light alone to project them out of the system.
“The dust is definitely present and is illuminated by the star,” Schirmer points out. “But, It simply doesn’t provide enough strength to explain what we observed.”
So how do stellar winds spread the seeds of life? The scientist also admits that other unexpected factorssuch as dramatic episodes of dust formation, can act in conjunction with these phenomena and “help explain how these winds are released” into the cosmos.
The mystery, which was not there, deepens.
