Pollux (star)
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Star Pollux (β Gem) |
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| Size comparison between Pollux (left) and the sun (top right) | |||||||||||||||||||||
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| AladinLite | |||||||||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Twins | ||||||||||||||||||||
| Right ascension | 07 h 45 m 18.95 s | ||||||||||||||||||||
| declination | + 28 ° 01 ′ 34.3 ″ | ||||||||||||||||||||
| Apparent brightness | 1.16 mag | ||||||||||||||||||||
| Typing | |||||||||||||||||||||
| Known exoplanets | 1 | ||||||||||||||||||||
| B − V color index | +1.00 | ||||||||||||||||||||
| U − B color index | +0.85 | ||||||||||||||||||||
| R − I index | +0.50 | ||||||||||||||||||||
| Spectral class | K0 IIIvar | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | (3.2 ± 0.1) km / s | ||||||||||||||||||||
| parallax | (96.54 ± 0.27) mas | ||||||||||||||||||||
| distance | (33.785 ± 0.094) Lj (10.358 ± 0.029) pc |
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| Visual absolute brightness M vis | +1.08 likes | ||||||||||||||||||||
| Proper movement | |||||||||||||||||||||
| Rec. Share: | (−626.55 ± 0.30) mas / a | ||||||||||||||||||||
| Dec. portion: | (−45.80 ± 0.18) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Dimensions | 1.86 M ☉ | ||||||||||||||||||||
| radius | (9.14 ± 0.71) R ☉ | ||||||||||||||||||||
| Luminosity |
32 L ☉ |
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| Effective temperature | 4500 K | ||||||||||||||||||||
| Rotation time | 38 d | ||||||||||||||||||||
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Other names and catalog entries |
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Pollux (β Geminorum) is the brightest star in the constellation Gemini and part of the large winter hexagon , which it forms with 5 other stars of 1st magnitude . The name is the Latin form of Polydeukes , one of the Dioscuri in Greek mythology.
properties
Astrophysically, Pollux is one of the red giants . At a distance of about 34 light years , it is the closest representative of this star class to our solar system. Pollux has about eight times the radius of the sun, its mass is about 1.86 solar masses . It has 32 times the luminosity of the sun at a surface temperature of 4500 Kelvin .
Pollux is the seventeenth brightest star in the night sky. Its reddish color contrasts strikingly with its almost equally bright neighboring star Castor (α Geminorum).
planet
From spectroscopic measurements of its radial velocity it was concluded that Pollux will be orbited by a planet with 3 times the mass of Jupiter ( Thestias alias Pollux b or β Gem b) in 590 days. This makes it the brightest star seen from Earth that has so far been identified as having a planetary companion.
See also
Literature and individual references
- ↑ a b c Hipparcos catalog (ESA 1997)
- ↑ a b c Bright Star Catalog
- ↑ Pulkovo radial velocities for 35493 HIP stars
- ↑ a b c Hipparcos, the New Reduction (van Leeuwen, 2007)
- ↑ a b c Hatzes et al .: Long-period radial velocity variations in three K giants . In: The Astrophysical Journal . 413, 1993, pp. 339-348. bibcode : 1993ApJ ... 413..339H .
- ↑ JMMC Stellar Diameters Catalog - JSDC (Lafrasse +, 2010) (calculated from the data values LDD and Plx)
- ^ Hatzes et al .: Confirmation of the planet hypothesis for the long-period radial velocity variations of β Geminorum . In: Astronomy and Astrophysics . 457, 2006, pp. 335-341.
- ^ Reffert et al .: Precise Radial Velocities of Giant Stars. II. Pollux and Its Planetary Companion . In: The Astrophysical Journal . 652, 2006, pp. 661-665.
