The nearest planetary system to our own has two asteroid belts in addition to a previously known ice belt, according to the latest observations by NASA’s Spitzer Space Telescope. The location and structure of the asteroid belts relative to the system’s central star, Epsilon Eridani, suggests the existence of earth-like planets. “We certainly haven’t seen it yet, but if its solar system is anything like ours, then there should be planets like ours,” says astronomer Massimo Marengo of the Harvard-Smithsonian Center for Astrophysics [USA Today].
The Epsilon Edidani system has long been of interest to astronomers and science fiction fans alike because of its proximity (10.5 light-years) and resemblance to our solar system. The newly discovered asteroid belts give the system an appearance even more like our own. The inner asteroid belt looks identical to ours in terms of material, and it orbits at 3 astronomical units (AU) from Epsilon Eridani — the same distance between the sun and the rocky asteroid belt between Mars and Jupiter. (An astronomical unit equals the average Earth-sun distance of 93 million miles, or about 150 million km.) Epsilon Eridani’s second asteroid belt is 20 AU from the star, or about where Uranus is in relation to our sun, and it is crowded with as much mass as Earth’s moon [Science News]. The outer asteroid belt was captured directly by Spitzer’s infrared cameras and the inner asteriod belt, though too far from the cameras, was indicated by the thermal energy from its infrared emissions.
A Jupiter-mass planet discovered in 2000 is thought to orbit just outside of the inner asteroid belt. The new study, to be published in an upcoming issue of The Astrophysical Journal, supports the existence of more planets because the asteroid belts were likely shaped by planets whose gravitational forces could remove any excess material flung from the belts, while also keeping the shape of the rings. Planets in our solar system exert similar shaping effects. “The big planets that are now keeping those gaps are determining the geometry of the system of rings,” [SPACE.com] says Marengo.
Epsilon Eridani is nearly the same mass as our sun but only about one-fifth as old. While the sun is an estimated 4.5 billion years old, Epsilon Eridani has been around for just 850 million years. “Studying Epsilon Eridani is like having a time machine to look at our solar system when it was young,” [SPACE.com] says Marengo. Trekkies will also recognize the star as the home of logical Mr. Spock. Marengo adds, “Of course there is disagreement among Star Trek fans about whether the planet of Mr. Spock could be at Epsilon Eridani, because it is such a young star and Vulcans are supposed to be an advanced civilization” [USA Today].