Tau-1 Eridani, a white main-sequence star in Eridanus
Tau-1 Eridani is a white main-sequence star in the constellation Eridanus. At 46 light years away, it shines at an apparent visual magnitude of 4.47.
Tau-1 Eridani (HIP 12843)
Tau-1 Eridani is a white main-sequence star in the constellation Eridanus. At 46 light years away, it shines at an apparent visual magnitude of 4.47. The star's age is estimated to be 3 billion years but is certainly no less than 2.3 billion years and no greater than 3.6 billion years. The iron abundance of Tau-1 Eridani is +0.02 (104.7% of the Sun). It is moving through the Galaxy at a speed of 34.3 km/s relative to the Sun. Its projected Galactic orbit carries it between 22,100 and 25,200 light years from the center of the Galaxy. It came closest to the Sun 306,000 years ago when it had brightened to magnitude 3.55 from a distance of 30 light years.
Sky position: RA 2h 45.1m, Dec -18° 34.2'
Common designations: Tau-1 Eridani, 1 Eridani, HIP 12843, HD 17206, Gliese 111
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Brightest stars in Eridanus:
(list all)
| Rank | Mag. | Star |
| 23 | 4.25 | Lambda Eridani |
| 24 | 4.26 | 82 Eridani |
| 25 | 4.26 | Tau-5 Eridani |
| 26 | 4.30 | f Eridani |
| 27 | 4.32 | 54 Eridani |
| 28 | 4.36 | Omega Eridani |
| 29 | 4.43 | Pi Eridani |
| 30 | 4.43 | Keid |
| 31 | 4.46 | 32 Eridani |
32
| 4.47
) Tau-1 Eridani
| Rank | Mag. | Star |
| 33 | 4.49 | Upsilon-1 Eridani |
| 34 | 4.57 | y Eridani |
| 35 | 4.59 | h Eridani |
| 36 | 4.62 | Tau-9 Eridani |
| 37 | 4.64 | Tau-8 Eridani |
| 38 | 4.74 | s Eridani |
| 39 | 4.74 | 17 Eridani |
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Galactic Orbit of Tau-1 Eridani
(compared to the Sun)
E
ccentricity: 6.5% vs. 16.0%Angle φ : -112.5°vs. 26.0°
Semi-major axis : 7,253 pc vs. 8,686 pc
Semi-minor axis: 7,238 pc vs. 8,574 pc
Focus-to-center
: 469 pcvs. 1,388 pcSemilatus rectum : 7,223 pc vs. 8,464 pc
Perigalacticon: 6,784 pc vs. 7,297 pc
Apogalacticon
: 7,722 pcvs. 10,074 pcSome Tabulated XHIP Data for Tau-1 Eridani
(see also: SIMBAD)
Astrometry
2007A&A...474..653V
| Position | Proper Motion | |
| Right Ascension: | 41.27492268° ±1.23 mas | 332.17 ±0.85 mas/yr. |
| Declination: | -18.57265010° ±1.36 mas | 35.10 ±0.88 mas/yr. |
| Galactic Longitude: | 200.83307349° | 99.48 mas/yr. |
| Galactic Latitude: | -62.52730077° | 318.86 mas/yr. |
Parallax: 70.32 ± 1.83 mas
Spectrography
Spectral Type: F7V 2009ApJS..180..117A.
Radial Velocity:
25.90 ±0.80 km/s [B rating]
2007A&A...475..519H.
This star is a spectroscopic binary with an unsolved orbit.
Iron Abundance [Fe/H]:
0.02 ±0.02 dex
2011A&A...530A.138C, 2006AJ....131.3069L, 2005ApJS..161..444T, 2005AJ....129.1063L, 2004A&A...420..183A.
Photometry
| band | magnitude | Abs. Mag. |
| U | ||
| B | 4.95 | 4.19 |
| V | 4.47 | 3.71 |
| R | ||
| I | 3.98 | 3.22 |
| J | 3.49 | 2.72 |
| H | 3.24 | 2.47 |
| K | 3.25 | 2.49 |
B-V: +0.48 V-I: +0.49
Derivations
Heliocentric distance: 14.21 pc (2.6% margin of error)
Galactocentric distance: 7,406 pc
Transverse velocity: 22.5 km/s
3D heliocentric position and motion:
|
toward: |
Galactic center | Galactic rotation | North Galactic Pole |
| Position ( X, Y, Z) | -6.1 pc | -2.3 pc | -12.6 pc |
| Velocity (U, V, W) | -26.6 km/s | -17.3 km/s | -13.1 km/s |