Cienciaes.com: Birth of binary stars. We spoke with Felipe de Oliveira Alves.

2019-10-18 13:41:52

If we had the chance to take a space walk to visit the closest stars to the Sun, our first stop would be Alpha Centauri, a system that gravitationally binds three stars. The first two orbit at an average distance similar to that which separates Saturn from the Sun and the third, Proxima Centauri, revolves around the previous two. It might seem strange to us that a triple system exists right in our neighborhood, but it is nothing extraordinary, in fact, more than half of the stars close to the Sun form binary or multiple systems.

If binary stars are so abundant, it stands to reason that we wonder how they originate. Of course, it is not possible to observe how a star evolves, our life is too short compared to theirs. However, what we can do is observe many stars and obtain a set of still images that reveal different moments in their existence. Astrophysicists usually explain this procedure with a very eloquent example. If a fly wanted to investigate what life is like for a human being, taking into account that its existence only lasts a few days, what it could do is observe the people around it. The fly would see pregnant women, babies, children, adults, old people… each one of them is a fixed image but when they are related to each other, they allow us to know what human life is like. This is how, by observing the stars in the firmament and using the physical laws that science provides us, we have managed to know what the life of the stars is like.

Now, a team of researchers led by our guest on Talking to Scientists, Felipe de Oliveira Alveshas recently published in the magazine Science the image of the birth of a binary star system. The researchers pointed the 66 antennas of the complex “ALMA (Atacama Large Millimeter / submillimeter Array )“ del European Southern Observatory in Chile, towards a small region of the Pipa nebula (fig. 1). This nebula is a huge cloud of gas and dust that obscures the view of the millions of stars in the Milky Way behind it. Its appearance is reminiscent of a smoking pipe, hence its name.

In a portion of the nebula, known as Barnard 59, a small cluster of young stars is observed. Felipe de Oliveira Alves and his colleagues pointed the complex there ALMA to observe a disk of matter about 90 astronomical units in radius that is fueling a stellar birth. The first images, of lower resolution, allowed us to see a disk of matter that, like an enormous cocoon, enclosed the place where stars are formed (fig. 2). By enlarging the vision, using ALMA in its most extended version, a high-resolution image was obtained (fig. 3) that reveals the presence of two much smaller disks of matter, each of which hides a nascent star.

The image made it possible to detect filaments of gas and dust that route matter from the circumbinary disk to the smaller disks that surround the stars in the interior. The subsequent study of the chemistry of the cloud and the movements of the gases revealed that matter is concentrating at a higher rate in the component with the lowest mass, something that had already been predicted by theoretical models and that has now been validated. for these observations.

I invite you to listen to Felipe de Oliveira AlvesBrazilian researcher at the “Center for Astrochemical Studies of the Max-Planck-Institut für extraterrestrische Physik“

Reference:
Alves et al., Gas flow and accretion via spiral streamers and circumstellar disks in a young binary protostar. Science 04 Oct 2019: Vol. 366, Issue 6461, pp. 90-93 DOI: 10.1126/science.aaw3491