Epsilon Eridani system turning out to be extremely interesting: two asteroid belts, possibly Earth-like planet(s)

Wednesday, October 29, 2008

Size of Epsilon Eridani, compared to the Sun on the right.

Take a look at this article from New Scientist today on Epsilon Eridani, a solar system especially interesting because of its proximity to Earth, a mere 10 light-years, or the 9th closest system to Earth. It is moving away from us at 15 km/s though, compared to Alpha Centauri which is approaching at a velocity of 21 km/s and Barnard's Star at 106 km/s. In terms of interstellar travel though, that's nothing of course; I just like the thought that a star like Alpha Centauri is now some 130 AU (more than four times the distance from the Sun to Neptune) closer to the Earth than before I was born.

Back to the subject: here's what makes this system so interesting:
The belts were found in orbit around the nearby star Epsilon Eridani, which sits just 10.5 light years from Earth. The star boasts a planet that orbits once every 7 years and weighs about 60% the mass of Jupiter. Astronomers have also previously detected a far-out ring of icy material around the star, similar to our own Kuiper belt.

Now, two rocky asteroid belts have been found much closer to the star, a new study suggests. Dana Backman of the SETI Institute in Mountain View, California, and colleagues caught the warmer glow of the two belts using NASA's Spitzer Space Telescope, which images objects at infrared wavelengths.
Smaller planets could also be lurking inside Epsilon Eridani's inner asteroid belt. "I would put money on there being an Earth-like planet in the space between the inner asteroid belt and the star," Backman told New Scientist.

The star is close enough that an Earth-like planet might be directly imaged with future telescopes, such as the Terrestrial Planet Finder Interferometer, a proposed orbiting array of telescopes currently being considered by NASA. The system might "be the first one where you could point to a pale blue dot and say, 'There's the Earth,'" Backman told New Scientist.
Wikipedia also has a fair bit of information on the system, such as these facts:

  • There are no planets within the system with a mass of 3 or more Jupiter masses,
  • "The dust disk contains approximately 1000 times more dust than is present in the inner system around our Sun, which may mean it has about 1000 times as much cometary material as our solar system" (this one's uncited though so careful)
  • "Epsilon Eridani has an estimated 85% of the Sun's mass and 84% of the Sun's radius, but has only 28% of its luminosity."
  • "The maximum habitable zone for Epsilon Eridani currently stretches from about 0.5–1.0 Astronomical Units." <-- Venus orbits at 0.7 AU for comparison.


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