Like our Kuiper Belt: ALMA finds 74 belts of exocomets around other stars
Behind the planets in the solar system is the Kuiper Belt. An inventory of similar structures around other stars shows how unusual it is.
Compilation of the discovered belts around other stars
(Image: ALMA (ESO/NAOJ/NRAO)/SMA/ L. MatrĂ et al.)
A research team has used several telescopes to take images of 74 different belts of exocomets orbiting comparatively close stars. This has now been made public by the European Southern Observatory ESO, whose ALMA telescope (Atacama Millimeter/submillimeter Array) played a central role in the work. The belts of planetesimals, or exocomets, roughly correspond to the Kuiper Belt at the edge of the solar system, but differ from each other in shape, size and age. It is therefore striking that the structures are larger and extend further out than expected. In addition, the objects in the rings would become smaller and smaller over time due to collisions.
Kuiper belt may also be larger than expected
In the solar system, the Kuiper Belt is a ring-shaped structure consisting of various large celestial bodies that is located behind Neptune. Among other things, many comets originate from there. It is currently assumed that its outer boundary is located at around 50 astronomical units (AU). Recently, however, there have been indications that it is significantly further away. They come from the Pluto probe New Horizons, which should have left the Kuiper Belt behind long ago. Nevertheless, it is still measuring far more dust particles in its surroundings than should actually be there. The finding now seems to match the inventory of dozens of similar belts in other stars.
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As the ESO now explains, it is extremely difficult to detect such structures around other stars, even though they are so large. This is due to their temperature: so far away from the respective star, the celestial bodies are between -250 and -150 degrees Celsius cold. This is why they only radiate in wavelengths that are undetectable by most telescopes. ALMA is an exception here.
The collection of such belts that has now been compiled gives an indication of how common or unusual the Kuiper Belt is. Future telescopes should even be able to detect rings or gaps in such belts. The current study is presented in the journal Astronomy and Astrophysics.
(mho)
