Illustration of an imaginary planet around a star with exozodiacal light. ESO / L. Calçada
RTVE.es/ESO
international team of astronomers discovered exozodiacal light near the habitable zones of nearby stars nine . That is, a starlight reflected by dust created after the asteroid collision and evaporation of comets.
The discovery was possible using the VLTI (Very Large Telescope Interferometer ) in the near-infrared range. In the future, the presence of such large amounts of dust in the inner regions surrounding some stars could be an obstacle to obtain direct images of planets as Earth.
The team of astronomers observed 92 stars to investigate the exozodiacal light from the warm dust close to their habitable zones, then combining the new data with previous observations, as reported the European Southern Observatory.
exozodiacal Bright light created by the glowing beads exozodiacal dust hot or the reflection of starlight on these grains, was observed in nine of the selected stars .
Diffuse Glow and White
On Earth, in places dark and clear skies, the zodiacal light seems a weak and diffuse white glow so visible in the night sky at the end of twilight or before sunrise.
It is caused by the reflection of sunlight on tiny particles and appears to extend from the vicinity of the sun. This not only reflected light is observed from Earth, it can be observed from the solar system.
This is the first large-scale light exozodiacal
The glow observed in this new study is a most extreme version of the same phenomenon . Although this light exozodiacal zodiacal-light systems around other estelares- had been previously detected, this is the first systematic large-scale study of this phenomenon around nearby stars.
Evolution of Earth-like planets
In contrast to previous observations, the team observed that in the future dust eventually form planets but noted the dust created by collisions between small planets , a few kilometers in size.
These objects, called planetesimals, similar to the asteroids and comets in the solar system. This type of dust is also the origin of the zodiacal light in the solar system.
“If we study the evolution of Earth-like near the habitable zone planets, we have to observe the zodiacal dust in these regions around other stars, “says Steve Ertel, lead author and researcher at ESO and the University of Grenoble (France).
” The detection and characterization of this kind of dust around other stars is a way to study the architecture and evolution of planetary systems “, explained.
Observations with high contrast
To detect dust (which emits very weakly) near the dazzling central star, it is necessary to carry out high-resolution observations with high contrast .
The interferometry, which combines the light collected at exactly the same time for several different-infrared telescopes is, so far, the only technique can discover and study such systems .
Using the capabilities of the VLTI and carrying the instrument to its limits (in terms of accuracy and efficiency), the team was able to achieve a level of performance ten times better than other instruments available in the world.
For each star, the team used the auxiliary telescopes 1.8 meters to provide light to VLTI . Where exozodical strong light it was, they were able to completely resolve the extensive disks of dust and spread their faint glow of light from the parent star.
By analyzing the properties of stars surrounded by a disk of dust exozodiacal, the team found that most of the dust was detected around older stars .
Detecting exoplanets
The sample of observed objects also included 14 stars around which were detected exoplanets .
All of these planets are in the same region in which the system is dust in systems with exozodiacal light. The presence of light exozodiacal planets in systems with can be a problem for future astronomical studies of exoplanets because exozodiacal dust, even at low levels, makes it much more difficult to detect of Earth-like planets with direct image.
“The high rate of detection at this very bright level, suggests that must be a significant number of systems containing weaker dust , undetectable in our polls, but much brighter than the zodiacal dust in the solar system, “explains Olivier Absil, co-author and researcher at the University of Liege.
No comments:
Post a Comment