A team of scientists from the University of Manchester and the University of Hong Kong has made progress in understanding the mysterious alignment of planetary nebulae. Planetary nebulae are gas clouds that are expelled by dying stars. These nebulae often take on beautiful shapes, such as an hourglass or butterfly.

Almost a decade ago, a Manchester doctoral student named Bryan Rees discovered the alignment of planetary nebulae, but its cause remained unknown. The recent study confirmed the alignment and identified a particular group of stars responsible: close binary stars.

The research team studied a collection of planetary nebulae in the Galactic Bulge, located near the center of the Milky Way. These nebulae are unrelated and come from different stars, but it was found that they were aligned nearly parallel to the galactic plane in the sky.

The study revealed that the alignment is only present in planetary nebulae that have a close companion star. The companion star orbits closely around the primary star at the center of the nebula. On the other hand, nebulae without close companions do not show alignment, suggesting that it is related to the initial separation of binary components during star formation.

This discovery brings scientists closer to understanding the cause of this alignment. It also provides information about the dynamics and evolution of the Galactic Bulge region. The alignment suggests that the fast orbital motion of the companion star can shape the nebulae, even leading the companion star to orbit within the central star.

In future studies, scientists will focus on unraveling the mechanisms behind this alignment. Understanding star formation in the galactic bulge is a complex process involving various factors such as gravity, turbulence, and magnetic fields. The importance of this research lies in the discovery that alignment is observed in a specific subset of planetary nebulae.

The study was carried out using the Very Large Telescope of the European Southern Observatory, examining 136 confirmed planetary nebulae in the galaxy’s bulge. High-resolution images from the Hubble Space Telescope were also used in the analysis.

This research was published in The Astrophysical Journal Letters.


– The Astrophysical Journal Letters