Pi Hydrae
Template:Location mark Location of π Hydra (circled) | |
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Hydra |
| Right ascension | Template:RA[1] |
| Declination | Template:DEC[1] |
| Apparent magnitude (V) | 3.25[2] |
| Characteristics | |
| Spectral type | K1 III–IV[3] or K2-III Fe-0.5[4] |
| U−B Template:Engvar | +1.040[5] |
| B−V Template:Engvar | +1.120[5] |
| Astrometry | |
| Radial velocity (Rv) | +26.7[2] km/s |
| Proper motion (μ) | RA: +43.70[1] mas/yr Dec.: −141.18[1] mas/yr |
| Parallax (π) | 32.30±0.16 mas[1] |
| Distance | Template:Rnd ± Template:Rnd ly (Template:Rnd ± Template:Rnd pc) |
| Absolute magnitude (MV) | 0.79[6] |
| Details[7] | |
| Mass | Script error: No such module "val". Template:Solar mass |
| Radius | Script error: No such module "val". Template:Solar radius |
| Luminosity | Script error: No such module "val". Template:Solar luminosity |
| Surface gravity (log g) | Script error: No such module "val". cgs |
| Temperature | Script error: No such module "val". K |
| Metallicity [Fe/H] | Script error: No such module "val". dex |
| Rotational velocity (v sin i) | 2.25[8] km/s |
| Age | Script error: No such module "val". Gyr |
| Metallicity [Fe/H] | {{{metal_fe2}}} dex |
| Other designations | |
| Template:Odlist[9] | |
| Database references | |
| SIMBAD | data |
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Pi Hydrae, Latinized from π Hydrae, is a star in the constellation Hydra with an apparent visual magnitude of 3.3,[2] making it visible to the naked eye. Parallax measurements put this star at a distance of about Script error: No such module "convert". from the Earth.
The spectrum of this star shows it to have a stellar classification of K1 III-IV,[3] with the luminosity class of 'III-IV' suggesting it is in an evolutionary transition stage somewhere between a subgiant and a giant star. It has a low projected rotational velocity of 2.25 km s−1.[8] Pi Hydrae is radiating 61 times the Sun's luminosity from its outer envelope with an effective temperature of 4,565 K,[7] giving it the orange hue of a K-type star.[10]
Pi Hydrae is a type of giant known as a cyanogen-weak star, which means that its spectrum displays weak absorption lines of CN− relative to the metallicity. (The last is a term astronomers use when describing the abundance of elements other than hydrogen and helium.) Otherwise, it appears to be a normal star of its evolutionary class, having undergone first dredge-up of nuclear fusion by-products onto its surface layers.[11]
References
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External links
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