Alpha 1 Capricorni
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Double star α 1 Capricorni |
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| α 1 cap in the constellation "Capricorn" | |||||||||||||||||||||
| AladinLite | |||||||||||||||||||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Capricorn | ||||||||||||||||||||
| Right ascension | 20 h 17 m 38.87 s | ||||||||||||||||||||
| declination | -12 ° 30 ′ 29.6 ″ | ||||||||||||||||||||
| Apparent brightness | 4.41 mag | ||||||||||||||||||||
| Typing | |||||||||||||||||||||
| B − V color index | 1.07 | ||||||||||||||||||||
| U − B color index | 0.80 | ||||||||||||||||||||
| R − I index | 0.55 | ||||||||||||||||||||
| Spectral class | G3 Ib | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | −25.79 ± 0.15 km / s | ||||||||||||||||||||
| parallax | (5.73 ± 0.33) mas | ||||||||||||||||||||
| distance | (570 ± 33) ly (175 ± 10) pc |
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| Bolometric absolute brightness M bol | −2.79 mag | ||||||||||||||||||||
| Proper movement | |||||||||||||||||||||
| Rec. Share: | (22.98 ± 0.32) mas / a | ||||||||||||||||||||
| Dec. portion: | (1.28 ± 0.28) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Dimensions | 5.3 M ☉ | ||||||||||||||||||||
| radius | 130 R ☉ | ||||||||||||||||||||
| Luminosity |
1050 L ☉ |
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| Effective temperature | 5300 K | ||||||||||||||||||||
| Metallicity [Fe / H] | +0.22 | ||||||||||||||||||||
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Other names and catalog entries |
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Alpha 1 Capricorni (α 1 Cap) is a telescopic and spectroscopic multiple star in the constellation Capricorn . It has a total brightness of 4.4 mag and its distance is about 570 light years .
Alpha 1 Capricorni is a system made up of at least five components. The main star A is a yellow supergiant with a little over 5 times the mass, 130 times the radius and 1000 times the luminosity of the sun . Its surface temperature is around 5300 K, a little below that of the sun.
In 1827, John Herschel found a companion C, 120 times weaker, with an apparent magnitude of 9.6 mag, next to the bright star A for around 30 arc seconds. This star is also called BD −12 ° 5682. Later, in 1874 , Sherburne Wesley Burnham was able to describe a third component B. This star has a brightness of only 14.1 mag and was about 15 arc seconds away from the main star A at the time of its discovery, today the distance is a little over 50 ".
In 1905 Carl Wilhelm Wirtz was finally able to recognize another companion D with a brightness of 14.2 mag and a distance of 30 ″ to component C, and on the other hand he was able to identify the main star A itself as a narrow spectroscopic double star. Its two components Aa and Ab have apparent magnitudes of 4.4 and 8.6 mag.
Alpha 1 was together with the star Alpha 2 Capricorni also with the proper name " Algiedi " or "Algedi" (from Arabic الجدي, DMG al-ǧady 'the billy goat'). To distinguish it from this, it was also called "Prima Giedi". According to the “IAU Catalog of Star Names” of the Working Group on Star Names (WGSN) of the IAU for the standardization of star names, the name in the form “Algedi” was only assigned to the lighter Alpha 2 Capricorni in 2016 .
Scientific research
In 2005, the influence of the star's rotation speed on the occurrence of various elements in its atmosphere was investigated for Alpha 1 Capricorni and other medium-weight stars with a mass between 5 and 20 M ☉ from observations at the European Southern Observatory in Chile . Values for the effective temperature, the force of gravity on the surface, microturbulence speed, brightness and mass, as well as the frequency of various elements were determined.
Individual evidence
- ↑ a b c d e VizieR: Hipparcos, the New Reduction (van Leeuwen, 2007) - The Astrometric Catalog
- ↑ a b VizieR: Stellar Photometry in Johnson's 11-color system (Ducati, 2002)
- ^ VizieR: Southern B and Be stars (Levenhagen +, 2006)
- ↑ VizieR: General Catalog of Stellar Radial Velocities (Wilson, 1953)
- ↑ a b c d e f g R. Smiljanic, B. Barbuy, JR De Medeiros, A. Maeder: CNO in evolved intermediate mass stars. In: Astronomy & Astrophysics. Vol. 449, 2006, doi: 10.1051 / 0004-6361: 20054377 , pp. 655-671 ( bibcode : 2006A & A ... 449..655S ).
- ^ VizieR: Catalog of Stellar Diameters (CADARS) (Pasinetti-Fracassini + 2001)
- ↑ VizieR: The Washington Visual Double Star Catalog (Mason + 2001-2014)
- ↑ Bulletin of the IAU Working Group on Star Names, No. 2. IAU Division C Education, Outreach and Heritage, 2016 ( PDF; 158 KB ).