Epsilon Indi
Star system in the constellation of Indus / From Wikipedia, the free encyclopedia
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Epsilon Indi, Latinized from ε Indi, is a star system located at a distance of approximately 12 light-years from Earth in the southern constellation of Indus. The star has an orange hue and is faintly visible to the naked eye with an apparent visual magnitude of 4.83.[2] It consists of a K-type main-sequence star, ε Indi A, and two brown dwarfs, ε Indi Ba and ε Indi Bb, in a wide orbit around it.[12] The brown dwarfs were discovered in 2003. ε Indi Ba is an early T dwarf (T1) and ε Indi Bb a late T dwarf (T6) separated by 0.6 arcseconds, with a projected distance of 1460 AU from their primary star.
Observation data Epoch J2000.0 Equinox J2000.0 (ICRS) | |
---|---|
Constellation | Indus |
Right ascension | 22h 03m 21.65363s[1] |
Declination | −56° 47′ 09.5228″[1] |
Apparent magnitude (V) | 4.8310±0.0005[2] |
Characteristics | |
Spectral type | K5V + T1 + T6[3] |
U−B color index | 1.00[4] |
B−V color index | 1.056±0.016[2] |
Astrometry | |
ε Ind A | |
Radial velocity (Rv) | −40.43±0.13[1] km/s |
Proper motion (μ) | RA: 3,966.661(86) mas/yr[1] Dec.: −2,536.192(92) mas/yr[1] |
Parallax (π) | 274.8431 ± 0.0956 mas[1] |
Distance | 11.867 ± 0.004 ly (3.638 ± 0.001 pc) |
Absolute magnitude (MV) | 6.89[5] |
ε Ind Ba/Bb | |
Parallax (π) | 270.6580 ± 0.6896 mas[6] |
Distance | 12.05 ± 0.03 ly (3.695 ± 0.009 pc) |
Orbit[7] | |
Primary | ε Ind Ba |
Companion | ε Ind Bb |
Period (P) | 11.0197 ± 0.0076 yr |
Semi-major axis (a) | 661.58 ± 0.37 mas (2.4058 ± 0.0040 au) |
Eccentricity (e) | 0.54042 ± 0.00063 |
Inclination (i) | 77.082 ± 0.032° |
Longitude of the node (Ω) | 147.959 ± 0.023° |
Argument of periastron (ω) (secondary) | 328.27 ± 0.12° |
Details[8] | |
ε Ind A | |
Mass | 0.762±0.038[3] M☉ |
Radius | 0.711±0.005 R☉ |
Luminosity | 0.21±0.02 L☉ |
Surface gravity (log g) | 4.63±0.01 cgs |
Temperature | 4,649±84 K |
Metallicity [Fe/H] | −0.13±0.06 dex |
Rotation | 35.732+0.006 −0.003 days[9] |
Rotational velocity (v sin i) | 2.00 km/s |
Age | 3.5+0.8 −1.0[7] Gyr |
ε Ind Ba/Bb | |
Mass | Ba: 66.92±0.36 MJup Bb: 53.25±0.29[7] MJup |
Radius | Ba: ~0.080–0.081 R☉ Bb: ~0.082–0.083[10] R☉ |
Luminosity | Ba: 0.00002037(81) L☉ Bb: 0.00000597(27)[7] L☉ |
Surface gravity (log g) | Ba: 5.43–5.45 Bb: 5.27–5.33[10] cgs |
Temperature | Ba: 1,352–1,385 K Bb: 976–1,011[10] K |
Other designations | |
Database references | |
SIMBAD | The system |
A | |
Bab | |
Bab (as X-ray source) |
ε Indi A has one known planet, ε Indi Ab, with a mass of 3.3 Jupiter masses in an elliptical orbit with a period of about 45 years. ε Indi Ab is the second-closest Jovian exoplanet, after ε Eridani b. The ε Indi system provides a benchmark case for the study of the formation of gas giants and brown dwarfs.[9]