Editing Epsilon Eridani (section)

=== Circumstellar discoveries ===

[[File:Epsilon eridani dustring.gif|right|thumb|Submillimeter wavelength image of a ring of dust particles around Epsilon Eridani (above centre). The brightest areas indicate the regions with the highest concentrations of dust.|alt=An uneven, multi-coloured ring arranged around a five-sided star at the middle, with the strongest concentration below centre. A smaller oval showing the scale of Pluto's orbit is in the lower right.]]

Based on apparent changes in the position of Epsilon Eridani between 1938 and 1972, [[Peter van de Kamp]] proposed that an unseen companion with an orbital period of 25&nbsp;years was causing gravitational [[Perturbation (astronomy)|perturbations]] in its position.<ref name=aj79_491 /> This claim was refuted in 1993 by [[Wulff-Dieter Heintz]] and the false detection was blamed on a systematic error in the [[photographic plate]]s.<ref name=aj105_3_1188 />

Launched in 1983, the [[space telescope]] [[IRAS]] detected [[Infrared astronomy|infrared]] emissions from stars near to the Sun,<ref name=apj278_L1 /> including an [[infrared excess|excess infrared emission]] from Epsilon Eridani.<ref name=pasp97_885 /> The observations indicated a disk of fine-grained [[cosmic dust]] was orbiting the star;<ref name=pasp97_885 /> this [[debris disk]] has since been extensively studied. Evidence for a planetary system was discovered in 1998 by the observation of asymmetries in this dust ring. The clumping in the dust distribution could be explained by gravitational interactions with a planet orbiting just inside the dust ring.<ref name=apj506_2_L133 />

In 1987, the detection of an orbiting planetary object was announced by Bruce Campbell, Gordon Walker and Stephenson Yang.<ref name=hesser1987 /><ref name=Campbell1988 /> From 1980 to 2000, a team of astronomers led by [[Artie P. Hatzes]] made [[radial velocity]] observations of Epsilon Eridani, measuring the [[Doppler spectroscopy|Doppler shift of the star along the line of sight]]. They found evidence of a planet orbiting the star with a period of about seven years.<ref name=apj544_2_L145 /> Although there is a high level of noise in the radial velocity data due to magnetic activity in its [[photosphere]],<ref name=iau202 /> any periodicity caused by this magnetic activity is expected to show a strong correlation with variations in [[emission line]]s of ionized calcium (the [[Calcium#H and K lines|Ca II H and K lines]]). Because no such correlation was found, a planetary companion was deemed the most likely cause.<ref name=apj133_6_2442 /> This discovery was supported by [[astrometric]] measurements of Epsilon Eridani made between 2001 and 2003 with the [[Hubble Space Telescope]], which showed evidence for [[gravitational perturbation]] of Epsilon Eridani by a planet.<ref name=aj132_2206 />