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AsianScientist (July 17, 2018) – In a study published in Nature Communications an international team of scientists discovered that the surface of the asteroid near the Earth Phaethon reflected less than light as
Scientifically, light is called electromagnetic waves. The waves interfere with the electric and magnetic fields, and the directions of these interferences can be random or aligned. When the electromagnetic effects of light are aligned, the light is said to be polarized. Scientists are interested in how polarization changes when sunlight is reflected on the surface of an asteroid.
In this study, an international team including astronomers from the National Astronomical Observatory of Japan (NAOJ), Seoul National University, Chiba Institute and others institutes, used the Pirka telescope at the Nayoro observatory in Hokkaido Japan. the asteroid near the Earth Phaethon. They studied changes in the polarization of light reflecting on Phaethon at many different lighting angles.
Discovered in 1983, Phaethon turned out to be the parent body of the Geminid meteor shower. It is an active asteroid with a confirmed dust ejection and has a surprisingly blue color. Researchers have found that at some angles the light reflected by the Phaeton is the most polarized light ever observed among the small bodies of the solar system.
One possible explanation for the high polarization is that the Phaethon surface could be darker than expected. The asteroid surfaces are covered with rubble. When light reflected from the rough surface strikes another part of the surface and is reflected once more before being picked up by the observer, these multiple scatterings make random polarization.
"If the albedo – the percentage of light reflected by Phaethon – is lower than previously thought, this would reduce the effectiveness of multiple scatterings. Therefore, highly polarized light that was only reflected once would dominate, "said Dr. Takashi Ito of NAOJ, who led the research team.
The rubble covering the surface of Phaethon could be made up of larger grains or larger porous than expected, which could also reduce the effectiveness of multiple scattering, said the researchers.They suggested sintering – the compaction of solid material at high temperature or pressure – as a possible mechanism for the production of these Because the surface of the Phaethon can be heated up to 1000 degrees Celsius during its closest passage to the Sun, extreme heat could cause sintering on the surface of the asteroid, resulting in coarser grains.
To help astronomers better characterize the surface geology of Phaetheon, the DESTINY probe + of the Japan Aerospace Exploration Agency, scheduled for launch in 2022, will take photos as she flies over the asteroid.
This article is in: Ito et al. (2018) Extremely strong polarization of an active asteroid (3200) Phaethon
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Source: National Astronomical Observatory of Japan
Disclaimer: This article does not necessarily reflect the view of AsianScientist or his staff.
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