Using ESA's Herschel space observatory, astronomers have discovered vast comet belts surrounding two nearby planetary systems known to host only Earth-to-Neptune-mass worlds. The comet reservoirs could have delivered life-giving oceans to the innermost planets.
In a previous Herschel study, scientists found that the dusty belt surrounding nearby star Fomalhaut must be maintained by collisions between comets.
In the new Herschel study, two more nearby planetary systems - GJ 581 and 61 Vir - have been found to host vast amounts of cometary debris.
Herschel detected the signatures of cold dust at 200°C below freezing, in quantities that mean these systems must have at least 10 times more comets than in our own Solar System's Kuiper Belt.
GJ 581, or Gliese 581, is a low-mass M dwarf star, the most common type of star in the Galaxy. Earlier studies have shown that it hosts at least four planets, including one that resides in the 'Goldilocks Zone' - the distance from the central sun where liquid surface water could exist.
The comet belt of GJ581 red dwarf seen by Herschel space observatory in three colors at the wavelength of 70, 100 and 160 microns taht are combined in this image.
There also is a galaxy on the background just on the right of the belt, as well as one in the lower left corner and over the belt. The images at the three wavelength have been taken by the instrument PACS on board Herschel.
Credit: ESA/Herschel/PACS/Jean-François Lestrade, Observatoire de Paris, France
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