An article published in the journal “Monthly Notices of the Royal Astronomical Society” describes the discovery of laser emissions in the Ant Nebula. A team of astronomers used observations conducted with ESA’s Herschel space observatory to detect a very rare phenomenon connected to a star’s death. It suggests the presence of a binary star system in the heart of the nebula.
The Ant Nebula, formally known as Mz 3 or better as Menzel 3 because it was discovered by the astronomer Donald Howard Menzel in 1922, is about 8,000 light years away from Earth. It’s a bipolar type planetary nebula since it has a double lobe symmetry. Despite the name, planetary nebulae are characteristics of a period that’s short in astronomical terms of a star’s agony.
Donald Howard Menzel was also one of the first to suggest that natural phenomena such as the one we now call laser could occur in nebulae. Natural masers, in which there are microwaves in place of visible light frequencies, are more common, so much so that even whole galaxies have been discovered that act in that way and are called megamasers for their size.
In the Ant Nebula’s case, the Herschel space observatory’s PACS and SPIRE instruments allowed to detect laser emissions from its core. Dr. Isabel Aleman, who led the team that conducted this study, explained that such a very rare type of emissions is due to the recombination of hydrogen, which is produced only in very specific physical conditions that require a large amount of very dense gas near the star.
A comparison of the observations made with the Herschel space observatory with theoretical models made it possible to discover that the density of the gas that emits the laser beams is about 10,000 times higher than that of the gas present in a typical planetary nebula and also in the Ant Nebula’s lobes. Albert Zijlstra, one of the authors of the study, pointed out that the only way to keep the gas close to the star is if it’s orbiting around it in a disk. This suggests the presence of a companion for the star in agony prevents the gas from dispersing.
In essence, that rare phenomenon is possible thanks to the combination of a binary system with a star in agony that influences the shape, the chemical properties and the evolution of the final phases of that star’s life. Not surprisingly, natural laser emissions are very rare.
Göran Pilbratt, a scientist at the Herschel mission, pointed out that ESA’s space observatory provided the perfect observation capabilities to detect lasers in the Ant Nebula. This discovery is a sort of tribute to Donald Howard Menzel, who discovered the Ant Nebula and hypothesized that nebulae can emit laser beams.
