First hints of planets found in 1998, 1999, and 2000

This discovery did not pop up out of nowhere. Instead, it was the latest in a methodical sequence of events which gained new momentum in recent years. In July 1998 by the Joint Astronomy Centre (JAC), the University of California at Los Angeles, and the Royal Observatory in Edinburgh, announced the discovery Images published in 1998 (right) included a large prominent bright spot within the dust ring that was thought to be indicative of a possible large planet. Closer to the star, the dust has been removed by some process. According to the JAC "a region near the star that is partially evacuated indicates that planets may have formed ... the presence of planets is the most likely explanation for the absence of dust in this region because planets absorb the dust when they form."

Subsequent comparisons between the observations made of this dust cloud and what has been observed in our own solar system led astronomers to further suspect that there was some sort of planetary system around Epsilon Eridani.

A paper presented at the 30th Annual Lunar and Planetary Science Conference in Marc 1999 reported that 'Numerical simulations of the orbital evolution of dust particles from Kuiper Belt objects show that the four giant planets, especially Neptune and Jupiter, impose distinct and dramatic signatures on the overall distribution of Kuiper belt dust particles. The signatures are very similar to those observed in Epsilon Eridani. Numerical simulations of dust particles in Epsilon Eridani show that if the features on the dust disk are caused by a planet, its mass has to be smaller than that of Jupiter but much larger than that of the Earth."

In March 2000, a paper was presented at the 31st Annual Lunar and Planetary Science Conference which also compared observations of Epsilon Eridani's dust cloud with numerical simulations of the dust cloud. The authors reported that "micrometer-to-millimeter sized interplanetary dust particles in our Solar System are created primarily from asteroid-asteroid collisions, from comet disintegration near the Sun, and from mutual collisions between the Edgeworth- Kuiper Belt (EKB) objects. Similar processes are likely to exist in other planetary systems as well. What makes the Epsilon Eridani disk differs from other circumstellar dust disks is the azimuthal brightness variation along the ring. If one compares the pattern of the variation with the modeled structures of the EKB dust disk , one finds global similarities between the two. Therefore, a simple explanation for the observed structures in Epsilon Eridani is that they are caused by perturbations from objects (planets) orbiting the star."

There may yet be additional planets awaiting discovery. According to the UT press release "The irregular shape of this ring may be due to another, undiscovered planet. "If there is indeed a second planet, the asymmetry of the disk would suggest that the planet is orbiting just inside the ring, at a distance of 30 AU -- much farther out than the planet we have found and with a much longer orbital period than the one we've discovered," according to Hatzes. "Thus, it might also be responsible for the possible overall slope in our velocity measurements. And where there's one planet, there may be more."