etoile binaire origine vie extraterrestre

Extraterrestrial life: A new study of binary stars could help better target research

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A binary star is a type of star system consisting of two stars orbiting a common center of gravity. Almost every other sun-sized star belongs to this category. According to a new study, this type of star shows a very different evolution of the planets surrounding it (compared to standard stars), particularly in relation to the evolution of the protoplanetary disk (composed of gas and dust) in its early stages. This discovery could allow a more targeted search for extraterrestrial life.

To understand the fundamental aspects of the birth of stars and planetary systems, American and Danish researchers began observing the binary star system NGC 1333-IRAS2A, surrounded by a protoplanetary disk of gas and dust. ” Binary clearly affects the evolution of the disk of matter around the main system. And this suggests that the binary stars influence the final composition of the forming planets, since most stars form as binary stars. “Said in a press release Edwin Bergin, co-author of the study and professor in the Department of Astronomy at the University of Michigan.

The new study published in the journal Nature points out that planetary systems form around binary stars in a very different way than around single stars like the Sun. The only known inhabited planet, Earth, revolves around a single star (the Sun), which may motivate the search for life only around similar stars. However, the differences in planetary evolution between the two systems highlighted by the researchers present a new avenue for comparative research that could allow better alignment of the search for life in the future.

66 telescopes in coordination to observe a snapshot of the binary star system

To observe the binary star system NGC 1333-IRAS2A, astronomers used the 66 ALMA telescopes in Chile, which worked in a coordinated manner. This achieves much better resolution than could be achieved with a single telescope. The binary system is located in the Perseus molecular cloud about 1000 light-years from Earth, which is relatively close for such an observation. The two stars in the system are separated by 200 astronomical units (AU) – one AU equals the average distance between Earth and the Sun.

Because observations can only provide a snapshot of a moment in the evolution of the system, the researchers performed computer simulations to go back and forth in time to the observed snapshot. For example, due to the duality of the star, the movement of gas and dust does not follow a continuous pattern and can accelerate for short periods (from ten to a hundred years every 1000 years). In fact, the two stars “orbit” each other, and their combined gravity affects the surrounding disk of gas and dust. This causes huge amounts of matter to fall towards the binary star. It then gets tens to hundreds of times brighter until it returns to its normal state.

The fall of material triggers significant heating. The heat makes the star much brighter than usual “, explains Rajika Kuruwita, postdoc at the Niels Bohr Institute. ” These explosions rip apart the disc of gas and dust. As the disk rebuilds, the explosions can still affect the structure of the eventual planetary system “.

In contrast, the system is still too young for planets to have formed, and the team hopes to use ALMA to gain more observing time to study the formation of planetary systems. But also comets, conducive to the contribution of life evolution factors. In fact, the researchers explain that comets often have high levels of ice, which contains organic molecules that are likely conserved in comets. Subsequent cometary impacts could then carry these molecules to the surface of orbiting planets.

The new James Webb Space Telescope will also soon be looking for signs of extraterrestrial life. Towards the end of the decade it will be joined by the ELT (European Large Telescope) and the very powerful SKA (Square Kilometer Array), both of which are scheduled to start observing in 2027.

Source: nature


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