page_title: Epsilon Eridani
section_title: Possible planets
hierarchical_section_title: Epsilon Eridani / Planetary system / Possible planets
caption_attribution_description: English: This artist's conception shows the closest known planetary system to our own, called Epsilon Eridani. Observations from NASA's Spitzer Space Telescope show that the system hosts two asteroid belts, in addition to previously identified candidate planets and an outer comet ring. Epsilon Eridani is located about 10 light-years away in the constellation Eridanus. It is visible in the night skies with the naked eye. The system's inner asteroid belt appears as the yellowish ring around the star, while the outer asteroid belt is in the foreground. The outermost comet ring is too far out to be seen in this view, but comets originating from it are shown in the upper right corner. Astronomers think that each of Epsilon Eridani's asteroid belts could have a planet orbiting just outside it, shepherding its rocky debris into a ring in the same way that Jupiter helps keep our asteroid belt confined. The planet near the inner belt was previously identified in 2000 via the radial velocity, or "star wobble," technique, while the planet near the outer belt was inferred when Spitzer discovered the belt. The inner belt orbits at a distance of about 3 astronomical units from its star —or about the same position as the asteroid belt in our own solar system (an astronomical unit is the distance between Earth and our sun). The second asteroid belt lies at about 20 astronomical units from the star, or a position comparable to Uranus in our solar system. The outer comet ring orbits from 35 to 90 astronomical units from the star; our solar system's analogous Kuiper Belt extends from about 30 to 50 astronomical units from the sun. Français&#160;: A traduire...
context_page_description: Epsilon Eridani, formally named Ran, is a star in the southern constellation of Eridanus, at a declination of 9.46° south of the celestial equator. This allows it to be visible from most of Earth's surface. At a distance of 10.5 light-years from the Sun, it has an apparent magnitude of 3.73. It is the third-closest individual star or star system visible to the unaided eye.
  The star is estimated to be less than a billion years old. Because of its relative youth, Epsilon Eridani has a higher level of magnetic activity than the present-day Sun, with a stellar wind 30 times as strong. Its rotation period is 11.2 days at the equator. Epsilon Eridani is smaller and less massive than the Sun, and has a comparatively lower level of elements heavier than helium. It is a main-sequence star of spectral class K2, which means that energy generated at the core through nuclear fusion of hydrogen is emitted from the surface at a temperature of about 5,000 K, giving it an orange hue.
  The Bayer designation ε Eridani was established in 1603 by Johann Bayer.
context_section_description: As one of the nearest Sun-like stars, Epsilon Eridani has been the target of many attempts to search for planetary companions. Its chromospheric activity and variability mean that finding planets with the radial velocity method is difficult, because the stellar activity may create signals that mimic the presence of planets. Searches for exoplanets around Epsilon Eridani with direct imaging have been unsuccessful.
  Infrared observation has shown there are no bodies of three or more Jupiter masses in this system, out to at least a distance of 500 AU from the host star. Planets with similar masses and temperatures as Jupiter should be detectable by Spitzer at distances beyond 80 AU, but none has been discovered in this range. Planets more than 150% as massive as Jupiter can be ruled out at the inner edge of the debris disk at 30–35 AU.
caption: Artist's impression, showing two asteroid belts and a planet orbiting Epsilon Eridani
exif: {}