2023-07-13 15:21:57
Ten years ago, astronomers discovered that “ghosts” of stars, those they more seriously call planetary nebulae, could find themselves oddly aligned in our sky. The mystery seems to be lifted today.
You will also be interested
[EN VIDÉO] Black holes, galaxies, nebulae: what would the sky look like if these objects were very close? A video published by Roscosmos invites us to discover a whole new kind of sky…
When stars reach the end of their life, they expel clouds of gas. This is what will happen to our Sun some five billion years from now. What astronomers call a planetary nebula will then form. A kind of ” ghost “ of our dying star.
The death of a star similar to the Sun observed live
And it’s not one, but several of a particular type of planetary nebula – so-called bipolar, butterfly-shaped nebulae – that a doctoral student at the University of Manchester (UK), Bryan Rees, had observed on the side of the galactic bulge, the thickest section of the Milky Way in which there are many stars, gas and dust, near the center of our Galaxy. Several amazingly aligned planetary nebulae. The axis of “ghostly butterfly” which they formed when they died, placing themselves just along the plane of our Milky Way. Bryan Rees was talking about “surprising and important discovery”.
It was some ten years ago now, and it will have been necessary to wait until now for new data to come to lift the mystery. Of the researchers from the University of Manchester and the University of Hong Kong indeed studied using the Very Large Telescope (VLT) from the European Southern Observatory (ESO) in Chile, no less than 136 planetary nebulae in the bulge of our Galaxy. And they re-studied 40 of these nebulae with high-resolution images from the Hubble Space Telescope.
A companion star in ambush
With these data, they confirm today that the planetary nebulae identified ten years ago are independent. From different stars. They were even born at different times and spend their lives in completely different places. Yet they line up in our sky and almost parallel to the plane of our Milky Way.
What this work reveals above all is that it is the planetary nebulae which present a close stellar companion which tend to align. Thus, the phenomenon occurs when a star orbits around the dying star, at a distance which is not even as great as that which separates Mercury from our Sun. Planetary nebulae without close companions do not align.
To understand why this is important, we must remember that the process of star formation in the bulge of our Galaxy is complex. It involves various factors such as gravity, turbulence and magnetic fields. However, until now, astronomers lacked evidence to determine which of these mechanisms could generate the observed alignment. But this work suggests that planetary nebulae may be shaped by the rapid orbital motion of a companion star, which may even end up orbiting inside the main star. Further studies will be needed to fully understand the mechanism. However, these results already provide important evidence for the presence of a constant and controlled process that has influenced star formation over billions of years and over great distances.
1689263229
#Mysterious #alignment #star #ghosts #heart #Milky #finally #explained