Discovered in 1983, the near-earth asteroid Phaethon intrigues researchers due to its unusual orbit. A group of astronomers recently studied in detail the trajectory along which this space block moves around the Sun. The researchers were also able to refine the rotation period and thermophysical characteristics of the asteroid. The results of the work were published on May 27 at arXiv.org.
Phaeton belongs to the Apollo group. Moving in orbit, the asteroid approaches the Sun at a record distance for objects of its class - all 0.14 astronomical units (about 21 million kilometers). Scientists consider Phaethon to be the main body of the Geminid meteor shower, which can be observed from Earth in mid-December.
Phaeton moves in an orbit that is characteristic of a comet, not an asteroid. The ellipse along which it flies around the Sun is strongly elongated (eccentricity 0.9) and crosses the orbits of four terrestrial planets. Such features of the orbit make scientists think that Phaethon is a silicate nucleus of a comet, which, flying around the Sun, has lost its ice shell.
To accurately determine the shape of an asteroid, you need photographs taken from different angles. These images usually take decades to produce. Josef Hanuš and his team analyzed 55 light curves of Phaeton, built between 1994 and 2015. Also, scientists independently obtained 29 new light curves using telescopes around the world.
“The data from each observation is equally important, and they all contributed to determining the shape of the object. We used 9 different telescopes in our work. The largest of these was the University of Hawaii's 2.2-meter telescope located on Mauna Kea,”Hanus said.
Using the light curves, scientists were able to get an idea of the shape of the asteroid. In addition, Hanus's group was able to determine its rotation period (3.6 hours) and its exact dimensions - 5.1 kilometers. These results are in good agreement with previous studies.
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The interest of the scientific community in Phaethon is currently growing, since in 2017 the maximum approach of the asteroid with the Earth is expected. In December next year, it will be only 10 million kilometers from us. Scientists plan to use several methods at once to study Phaeton in detail from a minimum distance.
“Our results will be used in planning future studies,” Hanus said.
In the near future, scientists hope to find out the composition of Phaeton and better understand the relationship of the asteroid with the Geminid meteor shower.
ALEX KUDRIN