Stellar Wind Flowers: The Impact of Stellar Companions on Red Giants

The extensive ATOMIUM project, in partnership with the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile and the European Southern Observatory (ESO), aims to map the powerful stellar winds emitted by around a dozen red giant stars. Thanks to ALMA's incredible resolution, this ambitious goal is now attainable. Initially, researchers anticipated that these stellar winds, millions of times stronger than our Sun's, would be spherical, just like the stars they originate from.

However, the observations revealed a surprising outcome. Instead of finding spherical stellar winds, researchers discovered varying shapes, with some resembling the intricate petals of a rose, as seen in the image of the winds surrounding R Aquilae. These patterns bear a striking similarity to those found in planetary nebulae.

The research team, led by Leen Decin at KULeuven, Belgium, suggests that a phenomenon called binary interaction is responsible for the unique shapes of red giant stars' stellar winds. Binary interaction, as the name implies, involves two celestial bodies. The hypothesis states that the stellar winds take on their distinctive shapes due to the influence of another star or a massive planet. Since stellar winds are precursors to planetary nebulae, the similarities in their structures imply that the same physics governs both phenomena. Thus, binary interaction appears to be the primary force sculpting planetary nebulae's morphologies.

Credit: ALMA (ESO/NAOJ/NRAO), Decin et al.