The zodiacal light observed from the earth can be seen shortly after dusk or before dawn. It appears as a faint glow emanating from the direction of the sunrise. This glow is caused by diffused sunlight from dust particles distributed throughout the interplanetary space.
And now, for the first time, astronomers have examined exosodiacal light in nine other star systems near habitable zones.
The observation was made possible by the use of the Very Large Telescope interferometer (VLTI), located at the Paranal Observatory in Chile, in near-infrared light. The interferometer was supplied with light from four 1, 8-meter auxiliary telescopes, which simulate a much larger telescope, equivalent to the diameter of the distance between the telescopes. This makes it possible to achieve extreme sensitivity in observations, distinguishing weak diffused light passing through habitable zones surrounding target stars.
Exozodiacal light has been observed before, but for the first time on a scale of dozens of targets.
The exosodiacal light found in this observation is not caused by dust particles forming disks around the stars that ultimately formed the planets. Like the zodiacal light of the solar system, the exosodiacal light of these stars is caused by the dust of asteroids and comets that existed throughout the evolution of these star systems.
This image captures the zodiacal light - a triangular glow, clearly visible in the night sky. The picture was taken at the La Silla Observatory, in Chile in September 2009.
"If we want to study the evolution of terrestrial planets close to the habitable zone, we must study the zodiacal dust in this region around other stars," said Steve Ertel of the University of Grenoble France. "The detection and identification of this type of dust around other stars is a way to study the architecture and evolution of planetary systems."
Since the dust produced should fall off over time, the researchers were surprised to find that all stars with exosodiacal light are actually older, contrary to this idea.
Since the exosodiacal light found in this study is 1000 times brighter than the zodiacal light in our solar system, the researchers note that it will be much more difficult to directly observe exoplanets within this glow. Bright exosodiacal light can simply drown out the reflected light of stars in exoplanets.