Global InformationEpsilon Eridani information
  | |
| Observation data Epoch J2000.0 Equinox J2000.0 | |
|---|---|
| Constellation | Eridanus |
| Pronunciation | /ˈrɑːn/ |
| Right ascension | 03h 32m 55.84496s[1] |
| Declination | −09° 27′ 29.7312″[1] |
| Apparent magnitude (V) | 3.736[2] |
| Characteristics | |
| Spectral type | K2V[3] |
| Apparent magnitude (B) | 4.61[4] |
| Apparent magnitude (V) | 3.73[4] |
| Apparent magnitude (J) | 2.228±0.298[5] |
| Apparent magnitude (H) | 1.880±0.276[5] |
| Apparent magnitude (K) | 1.776±0.286[5] |
| U−B colour index | +0.571[2] |
| B−V colour index | +0.887[2] |
| Variable type | BY Dra[4][6] |
| Astrometry | |
| Radial velocity (Rv) | +16.376±0.0019[7] km/s |
| Proper motion (μ) | RA: −975.17[1] mas/yr Dec.: 19.49[1] mas/yr |
| Parallax (π) | 311.37 ± 0.11 mas[8] |
| Distance | 10.475 ± 0.004 ly (3.212 ± 0.001 pc) |
| Absolute magnitude (MV) | 6.19[9] |
| Details | |
| Mass | 0.82±0.02[10][11] M☉ |
| Radius | 0.735±0.005[12] R☉ |
| Luminosity | 0.34[13] L☉ |
| Surface gravity (log g) | 4.30±0.08[10] cgs |
| Temperature | 5,084±5.9[14] K |
| Metallicity [Fe/H] | −0.13±0.04[15] dex |
| Rotation | 11.4 days[16] |
| Rotational velocity (v sin i) | 2.4±0.5[17] km/s |
| Age | 400–800[18] Myr |
| Other designations | |
Ran, ε Eri, 18 Eridani, BD−09°697, GJ 144, HD 22049, HIP 16537, HR 1084, SAO 130564, WDS J03330-0928, LHS 1557[4] | |
| Database references | |
| SIMBAD | The star |
| planet b | |
| planet c | |
Epsilon Eridani (Latinized from ε Eridani), proper name Ran,[19] is a star in the southern constellation of Eridanus. At a declination of −9.46°, it is visible from most of Earth's surface. Located at a distance 10.5 light-years (3.2 parsecs) from the Sun, it has an apparent magnitude of 3.73, making it the third-closest individual star (or star system) visible to the naked eye.
The star is estimated to be less than a billion years old.[20] This relative youth gives Epsilon Eridani a higher level of magnetic activity than the Sun, with a stellar wind 30 times as strong. The star's rotation period is 11.2 days at the equator. Epsilon Eridani is smaller and less massive than the Sun, and has a lower level of elements heavier than helium.[21] It is a main-sequence star of spectral class K2, with an effective temperature of about 5,000 K (8,500 °F), giving it an orange hue. It is a candidate member of the Ursa Major moving group of stars, which share a similar motion through the Milky Way, implying these stars shared a common origin in an open cluster.
Periodic changes in Epsilon Eridani's radial velocity have yielded evidence of a giant planet orbiting it, designated Epsilon Eridani b.[22] The discovery of the planet was initially controversial,[23] but most astronomers now regard the planet as confirmed. In 2015 the planet was given the proper name AEgir [sic].[24] The Epsilon Eridani planetary system also includes a debris disc consisting of a Kuiper belt analogue at 70 au from the star and warm dust between about 3 au and 20 au from the star.[25][26] The gap in the debris disc between 20 and 70 au implies the likely existence of outer planets in the system.
As one of the nearest Sun-like stars,[27] Epsilon Eridani has been the target of several observations in the search for extraterrestrial intelligence. Epsilon Eridani appears in science fiction stories and has been suggested as a destination for interstellar travel.[28] From Epsilon Eridani, the Sun would appear as a star in Serpens, with an apparent magnitude of 2.4.[note 1]
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