Epsilon Indi
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| Observation data Equinox J2000.0 (ICRS) |
|
|---|---|
| Constellation | Indus |
| Right ascension | 22h 03m 21.657s |
| Declination | -56° 47′ 09.51″ |
| Apparent magnitude (V) | 4.68 |
| Characteristics | |
| Spectral type | K5Ve |
| U-B color index | 1.00 |
| B-V color index | 1.05 |
| Variable type | None |
| Astrometry | |
| Radial velocity (Rv) | -40 km/s |
| Proper motion (μ) | RA: 3,961.41 mas/yr Dec.: -2,538.33 mas/yr |
| Parallax (π) | 275.79 ± 0.69 mas |
| Distance | 11.83 ± 0.03 ly (3.626 ± 0.009 pc) |
| Absolute magnitude (MV) | 6.88 |
| Details | |
| Mass | 0.77 M☉ |
| Radius | 0.76 R☉ |
| Luminosity | 0.15 L☉ |
| Temperature | 4,130 K |
| Metallicity | 60-110% |
| Rotation | 23 days (0.7 km/s) |
| Age | 1.3 × 109 years |
| Other designations | |
Epsilon Indi (ε Ind / ε Indi) is a star approximately 11.83 light years from Earth's solar system. This star has the second highest proper motion (second only to 61 Cygni) of any naked eye star, or possibly the third highest, since the magnitude 6.4 Groombridge 1830 is a naked eye star under exceptionally dark skies.
This star is suspected of being a member of a moving group of at least sixteen population I stars. [1] It has a space velocity relative to the Sun of 86 km/s.[a] The surface gravity is:
- log g = 4.65 ± 0.15
or slightly higher than the Sun.[2]
As seen from Epsilon Indi, the Sun is a 2nd magnitude star in Ursa Major, near the bowl of the Big Dipper.[b]
Contents |
[edit] Companions
In January 2003, astronomers announced the discovery of a brown dwarf with a mass of 47 ± 10 Jupiter masses in orbit around Epsilon Indi at a distance of about 1500 AU. In August of 2003, astronomers discovered that this brown dwarf was actually a binary brown dwarf with a separation of about 2.5 AU. Both are of spectral class T; the larger brown dwarf has a mass of 47 ± 10 Jupiter masses, and the smaller 28 ± 7 Jupiter masses.[3][4]
[edit] Extraterrestrial Life
This star is leading the list of 17,129 nearby stars most likely to have planets that could support complex life, compiled by Margaret Turnbull and Jill Tarter of the Carnegie Institution in Washington.[5]
[edit] See also
[edit] Notes
| a. | ^ The space velocity components are: U = -77; V = -38, and W = +4. This yields a net space velocity of  km/s. |
| b. | ^ From Episilon Indi the Sun would appear on the diametrically opposite side of the sky at the coordinates RA=12h 03m 21s, Dec=56° 47′ 10″, which is located near Delta Ursae Majoris. The absolute magnitude of the Sun is 4.8, so, at a distance of 3.63 parsecs, the Sun would have an apparent magnitude  . |
[edit] References
- ^ Eggen, O. J. (1971). "The zeta Herculis, sigma Puppis, ε Indi, and eta Cephei Groups of Old Disk Population Stars". Publications of the Astronomical Society of the Pacific 83 (493): 251-270.
- ^ Kollatschny, W. (1980). "A model atmosphere of the late type dwarf Epsilon INDI". Astronomy and Astrophysics 86 (3): 308-314.
- ^ K. Volk, R. Blum, G. Walker, P. Puxley (August, 2003). epsilon Indi B. IAU. Retrieved on November 29, 2006.
- ^ M. J. McCaughrean, L. M. Close, R.-D. Scholz, R. Lenzen, B. Biller, W. Brandner, M. Hartung, N. Lodieu (2004). "ε Indi Ba,Bb: The nearest binary brown dwarf". Astronomy and Astrophysics 413: 1029-1036.
- ^ Stahl, Jason (January 2007). 20 Things You Didn't Know About... Aliens. Discover. Retrieved on March 2, 2007.
[edit] External links
- "Closest Known Brown Dwarf has a Companion", SpaceRef.ca, September 19, 2003. Retrieved on November 29, 2006.
- Epsilon Indi. Sol Company (2005). Retrieved on November 29, 2006.
- Kaler, Jim. Epsilon Indi. Retrieved on November 29, 2006.
