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58 Eridani is located about 43.4 light-years (ly) from Sol. It lies in the northwestern corner of (4:47:36.3:-16:56:4.0, ICRS 2000.0) of Constellation Eridanus, the River. The star can be found: west of Zaurak (Gamma Eridani); southwest of Cursa (Beta Eridani) and Rigel (Beta Orionis); northwest of Mu, Alpha (Arneb), and Beta Leporis (Nihal); and southeast of Keid and Beid (Omicron2 and Omicron1 Eridani, respectively). As 58 Eridani has become one of the top 100 target stars for NASA's planned Terrestrial Planet Finder (TPF), images of this star and its position relative to the Milky Way in Earth's night sky are now available from the TPF-C team.
58 Eridani is a yellow-orange main sequence dwarf star of spectral and luminosity type G1-3 V. Similar to Sol (Giusa Cayrel de Strobel, 1996), this "Solar analogue" may have roughly the same mass, around 96 to 99 percent of its diameter (Pasinetti-Fracassini et al, 2001; Perrin and Karoji, 1987; and Johnson and Wright, 1983, page 655), and 96 percent of its luminosity. It appears to be around 97 percent as enriched than Sol in elements heavier than hydrogen ("metals") based on its abundance of iron (B.J. Taylor, 2003).
The star is considered to be a nearby, young Solar analogue -- with a spectral type from G0 to K2 and a coronal x-ray luminosity suggesting an age of less than 800 million years (Gaidos and Gonalez, 2002; and Eric J. Gaidos, 1998). Little 10-micron emission from silicate dust in a circumstellar disk around the star was found suggesting that 58 Eridani may be more than 400 million years old although significant excess infrared emission was detected (Gaidos and Koresko, 2003). The star has "a combination of differential rotation and concentration of starspot activity at different stellar latitudes from year to year" (Guidos et al, 2000, in pdf). Useful catalogue numbers and designations for the star include: 58 Eri, HR 1532, Gl 177, Hip 22263, HD 30495, BD-17 954, SAO 149888, and LTT 2088.
An Earth-type planet with liquid water on its surface would require a stable orbit centered around 0.96 AU from 58 Eridani -- just under the orbital distance of Earth in the Solar System. Such a planet would have an orbital period lasting close to an Earth year. However, given its conjectured young age, an Earth-sized planet is not likely to have developed an oxygen-rich atmosphere but is likely to be under heavy bombardment by asteroids and comets. Astronomers are hoping to use NASA's Terrestrial Planet Finder (TPF) and the ESA's Darwin planned groups of observatories to search for a rocky inner planet in the so-called "habitable zone" (HZ) around 58 Eridani. As currently planned, the TPF will include two complementary observatory groups: a visible-light coronagraph to launch around 2014; and a "formation-flying" infrared interferometer to launch before 2020, while Darwin will launch a flotilla of three mid-infrared telescopes and a fourth communications hub beginning in 2015.
The following table includes all star systems known to be located within 10 light-years (ly), plus more bright stars within 10 to 20 ly, of 58 Eridani.
|Star System||Spectra &|
|L 736-30||M3 V||3.3|
|BD-21 1074 AB||M2 V |
|BD-11 916||M1 V||8.5|
|LP 833-42||M3.5 V||9.2|
|* plus bright stars *||. . .|
|Eta Leporis||F0-1 V-III||15|
|Gamma Leporis 2||F6-7 V |
|BD+04 701||F8 V||17|
|BD-04 1244||G2-4 V||18|
|10 Tauri 2?||F8-9 V-IV||19|
|Alpha Fornacis 2||F8 V-IV |
Up-to-date technical summaries on these stars can be found at: the Astronomiches Rechen-Institut at Heidelberg's ARICNS, and the Nearby Stars Database. Additional information may be available at Roger Wilcox's Internet Stellar Database.
Eridanus, the river, wends its way from the Hunter's foot of Orion then southwest to the southern circumpolar zone to enclose a larger area of sky than any other constellation. For more information on stars and other objects in Constellation Eridanus and an illustration, go to Christine Kronberg's Eridanus. Another illustration is available at David Haworth's Eridanus.
For more information about stars including spectral and luminosity class codes, go to ChView's webpage on The Stars of the Milky Way.
Note: Nominated as a "notable nearby star" by Ronald Botterweg.
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