R Hydrae
 Location of R Hydrae (circled) |
|
| Observation data Epoch J2000 Equinox J2000 |
|
|---|---|
| Constellation | Hydra |
| Right ascension | 13h 29m 42.80s |
| Declination | −23° 16′ 53.0″ |
| Apparent magnitude (V) | 3.5 to 10.9 (variable) |
| Characteristics | |
| Spectral type | M6e/M9e: |
| B−V color index | 1.3 |
| Variable type | Mira(period 388.87 days) |
| Astrometry | |
| Radial velocity (Rv) | −10.4 km/s |
| Parallax (π) | 8.05 ± 0.69 mas |
| Distance | 410 ± 30 ly (120 ± 10 pc) |
| Details | |
| Mass | 2 M☉ |
| Radius | 460 (variable) R☉ |
| Luminosity | 10,000 (variable) L☉ |
| Temperature | 2,830 K |
| Other designations | |
| Database references | |
| SIMBAD | data |
R Hydrae, also known as R Hya, is a Mira-type variable star in the constellation Hydra.
The magnitude of R Hydrae varies over a period of 389 days, between 3.5 and 10.9. The period of R Hydrae changes slowly.
At maximum brightness the star can be seen with the naked eye, while at minimum a telescope of at least 5 cm is needed.
R Hydrae is approximately 400 light years from Earth. Its spectral class is M7IIIe.
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