'Exozodiacal' Light Detected Around Alien Habitable Zones

Zodiacal light, as seen from Earth, can often be witnessed shortly after twilight or before dawn; it appears as a faint glow apparently emanating from the direction of the sun. This glow is caused by scattered sunlight from grains of dust distributed throughout interplanetary space.

Now, for the first time, astronomers have surveyed exozodiacal light — the same phenomena, albeit much brighter — in 9 other star systems near their habitable zones.

The observations were made possible through the use of the ESO’s Very Large Telescope Interferometer (VLTI), located at the Paranal Observatory in Chile, in near-infrared light. The interferometer was fed with light from four 1.8-metre Auxiliary Telescopes that imitate a much larger telescope of equivalent diameter as the distance between the telescopes. This allows extreme sensitivity in the observations, distinguishing the faint scattered light extending to the habitable zones surrounding the target stars.

Exozodiacal light has been observed before, but this is the first large-scale survey effort that has scanned dozens of targets.

The exozodiacal light detected in this survey is not caused by grains of dust that have formed disks around stars that will eventually go on to form planets. Like the solar system’s zodiacal light, these stars’ exozodiacal light is caused by the dust of asteroid and comets that have been ground up throughout the evolution of those star systems.

“If we want to study the evolution of Earth-like planets close to the habitable zone, we need to observe the zodiacal dust in this region around other stars,” said Steve Ertel, of ESO and the University of Grenoble in France. “Detecting and characterizing this kind of dust around other stars is a way to study the architecture and evolution of planetary systems.”

As dust production should diminish over time, the researchers were surprised to find that all the stars with exozodiacal light were in fact older, in contradiction to this idea.

As the exozodiacal light detected in this study is 1,000 times brighter than the zodiacal light in our solar system, the researchers point out that trying to directly image exoplanets within this glow will be made significantly harder. As the glow overlaps those stars’ habitable zones, the detection of Earth-sized exoplanets in habitable zones just became significantly harder — bright exozodiacal light may drown out the exoplanet’s own reflected starlight.

Read more at Discovery News