42 Draconis
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Star 42 Draconis |
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Dragon | ||||||||||||||||||
| Right ascension | 18 h 25 m 59.14 s | ||||||||||||||||||
| declination | + 65 ° 33 ′ 48.5 ″ | ||||||||||||||||||
| Apparent brightness | 4,833 likes | ||||||||||||||||||
| Typing | |||||||||||||||||||
| Known exoplanets | 1 | ||||||||||||||||||
| B − V color index | +1.187 | ||||||||||||||||||
| Spectral class | K1.5III | ||||||||||||||||||
| Astrometry | |||||||||||||||||||
| Radial velocity | 32.17 ± 0.20 km / s | ||||||||||||||||||
| parallax | 10.36 ± 0.20 mas | ||||||||||||||||||
| distance | 317.35 ± 16.3 Lj 97.3 ± 5 pc |
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| Visual absolute brightness M vis | -0.108 mag | ||||||||||||||||||
| Proper movement | |||||||||||||||||||
| Rec. Share: | +105.83 ± 0.21 mas / a | ||||||||||||||||||
| Dec. portion: | −27.24 ± 0.28 mas / a | ||||||||||||||||||
| Physical Properties | |||||||||||||||||||
| Dimensions | 0.98 ± 0.05 M ☉ | ||||||||||||||||||
| radius | 22.03 ± 1 R ☉ | ||||||||||||||||||
| Luminosity |
135 L ☉ |
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| Effective temperature | 4,200 ± 70 K | ||||||||||||||||||
| Metallicity [Fe / H] | −0.46 ± 0.05 | ||||||||||||||||||
| Age | 9.49 ± 1.76 billion a | ||||||||||||||||||
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Other names and catalog entries |
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42 Draconis (short 42 Dra ), also Fafnir , is a red giant in the constellation Dragon , which is about 317 light years away from the sun . It is a 5th magnitude star and can therefore be seen with the naked eye in a moonless night sky and without light pollution . 42 Draconis has a planetary system with at least one known exoplanet .
properties
42 Draconis belongs to the spectral class K1.5III and has a mass comparable to that of the sun, but its diameter is twenty-two times as large as it has already left the main sequence and is in the development phase of a red giant. It is a metal-poor star, the metallicity of which is only 35% of the Sun, and its age is 9.49 billion years. 42 Draconis is the northern pole star of Venus .
Planetary system
→ Main article: 42 Draconis b
In 2009, a planet orbiting the star with approximately four times the minimum mass of Jupiter was detected using the radial velocity method . This bears the systematic name 42 Draconis b.
Proper name
The star, which is rather inconspicuous to the naked eye, has no historical proper name. After a public competition by the International Astronomical Union (IAU) to name exoplanets and their central stars, 42 Draconis were named Fafnir on December 15, 2015, after the dwarf of the same name from Nordic mythology . The companion was given the name Orbitar . The name was proposed by the Brevard Astronomical Society , an astronomical association from Brevard County in Florida ( USA ).
Individual evidence
- ↑ a b c d e f SIMBAD: 42 Draconis. Retrieved January 3, 2016 .
- ↑ a b c d e f g The Extrasolar Planets Encyclopaedia: Planet 42 Dra b. (No longer available online.) Archived from the original on January 3, 2016 ; Retrieved January 3, 2016 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.
- ↑ International Astronomical Union: NameExoWorlds - The Approved Names. Retrieved January 3, 2016 .
