| Observation data Epoch J2000.0 Equinox J2000.0 |
|
|---|---|
| Constellation | Hydra |
| Right ascension | 09h 51m 28.6937s |
| Declination | -14° 50′ 47.771″ |
| Apparent magnitude (V) | 4.12 |
| Characteristics | |
| Spectral type | G6/8III[1] |
| Astrometry | |
| Distance | 273.48 ly (83.89 pc) |
| Details | |
| Mass | 3.34 [1] M☉ |
| Radius | 17.1 R☉ |
| Luminosity | 174[1] L☉ |
| Temperature | 5045[1] K |
| Age | 270[1] million years |
| Other designations | |
|
Upsilon 1 Hya, 39 Hya, HD 85444, BD-14 2963, HIP 48356, HR 3903, SAO 155542.
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Upsilon1 Hydrae is a yellow giant star in the constellation of Hydra. The star is one of Okayama Planet Search's main target for planet search and has turned out to host a substellar companion.
The Okayama Planet Search team published a paper in 2005 reporting investigations on radial velocity variations observed for a set of orange giant stars and announcing the detection of a brown dwarf companion in an eccentric orbit around Upsilon1 Hydrae.[2] The orbital period is roughly 4.1 years.
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity |
|---|---|---|---|---|
| b | ≥49 MJ | 3.9 | 1500 | 0.57 |