Tau Hydrae
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| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Hydra |
| Right ascension | 9h 29m 8.9s |
| Declination | -2° 46' 8" |
| Apparent magnitude (V) | +4.59 |
| Distance | 56 ly (17.18 pc) |
| Spectral type | F6V |
| Other designations | |
The Bayer designation Tau Hydrae (τ Hya / τ Hydrae) is shared by two star systems, τ¹ Hydrae and τ² Hydrae, in the constellation Hydra. The two stars are separated by 1.74° on the sky. Tau Hydrae also has the traditional name Ukdah, from the Arabic عقدة uqdah meaning the Knot.
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[edit] τ¹ Hydrae
Tau-1 Hydrae, also called Ukdah Prima ("First [Star] of the Knot"), is a binary star lying 56 light years from Earth. Tau-1 Hydrae is a spectral type F6 main sequence star which has an apparent magnitude of +4.59.
[edit] τ² Hydrae
| Observation data Epoch J2000.0 |
|
|---|---|
| Constellation (pronunciation) |
Hydra |
| Right ascension | 9h 31m 58.9s |
| Declination | -1° 11' 6" |
| Apparent magnitude (V) | +4.54 |
| Distance | 460 ly (141.10 pc) |
| Spectral type | A3V |
| Other designations | |
Tau-2 Hydrae, also called Ukdah Secunda ("Second [Star] of the Knot"), is a spectral type A3 main sequence star which has an apparent magnitude of +4.54. It is about 460 light years from Earth.
[edit] References
- HD 81997 -- Variable Star. SIMBAD Astronomical Database. Retrieved on 2006-11-05.
- HD 82446 -- Variable Star. SIMBAD Astronomical Database. Retrieved on 2006-11-05.
[edit] External links
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