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Based on a new study of how the phaethon near the Earth reflects light from different angles, astronomers believe that its surface may reflect less light than previously thought. It's an exciting mystery for the DESTINY + mission recently approved to study when it goes beyond Phaethon
The way an object reflects light depends not only on its albedo (the percentage of light that's in it). it reflects) but also from the angle of illumination. Researchers are particularly interested in how polarization changes when sunlight reflects off the surface of an asteroid.
Scientifically, light is called electromagnetic wave; waves create changes in electric and magnetic fields. The directions of these changes can be random or aligned. When the electromagnetic effects of the light are aligned, the light is said to be polarized.
An international team consisting of astronomers from the National Astronomical Observatory of Japan (NAOJ), the Seoul National University, the Chiba Institute of Technology, and the National Astronomical Institute of Japan. other institutes. used the 1.6-meter Pirka telescope at the Nayoro observatory in Hokkaido, Japan to observe the near-Earth asteroid (3200) Phaethon.
They studied the polarization changes of light reflected at different illumination angles. The results show that at certain angles, the light reflected by the Phaeton is the most polarized light ever observed among the small bodies of the solar system.
Discovered in 1983, Phaethon was shown as the parent body of the Geminid meteor shower. Most parental meteorites are comets, but Phaethon does not show typical cometary activity. Instead, it is an active asteroid with confirmed dust ejections. It also has a surprisingly blue color. The fact that its reflected light is strongly polarized is one more mystery surrounding this curious asteroid.
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 again before being reflected back to the observer, these multiple scatterings make random polarization.
Ito from NAOJ, a research team leader explains, "If albedo is lower than previously thought, it would reduce the effectiveness of multiple broadcasts, so that the strongly polarized light that has been reflected only once would dominate. " [19659002] Other possibilities that could reduce the effectiveness of multiple scatterings are that the rubble covering the surface of Phaethon could be composed of larger grains, or that the material could be more porous than expected. One possible mechanism for producing large grains is sintering.
The surface of the Phaethon can be heated up to 1000 degrees Celsius during its closest passage to the Sun. Such extreme heating can cause sintering on the surface of an asteroid, resulting in coarser grains.
The DESTINY + spacecraft of the Japan Aerospace Exploration Agency, scheduled for launch in 2022, will take pictures of Phaethon to help astronomers better characterize its surface geology.
Research Report: Extremely Strong Polarization of an Active Asteroid (3200) Phaethon, T. Ito et al., 2018 June 27, Nature Communications
Related Links
National Astronomical Observatory of the Japan
Asteroid and Comet Mission News, Science and Technology
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asteroid in search of the origin of life
Tokyo (AFP) June 27, 2018
A Japanese probe reached an asteroid at 300 million kilometers to collect information on the birth of the solar system and the origin of life after a trip of more than three years in the depths of space.
The Hayabusa2 probe has successfully installed in an observation position 20 kilometers (12 miles) above the Ryugu asteroid, said Wednesday officials from the Japanese Agency Aerospace exploration (JAXA).
The researchers began to applaud when the probe arrived on the scene, a feat … read more
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