Deneb Algedi
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Double star δ Capricorni |
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| δ 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 | 21 h 47 m 2.44 s | ||||||||||||||||||||
| declination | -16 ° 7 ′ 38.2 ″ | ||||||||||||||||||||
| Apparent brightness | 2.81-3.05 mag | ||||||||||||||||||||
| Typing | |||||||||||||||||||||
| B − V color index | 0.29 | ||||||||||||||||||||
| U − B color index | 0.10 | ||||||||||||||||||||
| R − I index | 0.16 | ||||||||||||||||||||
| Spectral class | kA5hF0mF2 III | ||||||||||||||||||||
| Variable star type | Algol | ||||||||||||||||||||
| Astrometry | |||||||||||||||||||||
| Radial velocity | (−3.4 ± 0.8) km / s | ||||||||||||||||||||
| parallax | (84.27 ± 0.19) mas | ||||||||||||||||||||
| distance | (38.70 ± 0.01) Lj (11,867 ± 0,003) pc |
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| Proper movement | |||||||||||||||||||||
| Rec. Share: | (261.70 ± 0.22) mas / a | ||||||||||||||||||||
| Dec. portion: | (−296.70 ± 0.14) mas / a | ||||||||||||||||||||
| Physical Properties | |||||||||||||||||||||
| Effective temperature | 7300 K | ||||||||||||||||||||
| Metallicity [Fe / H] | −0.13 | ||||||||||||||||||||
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Other names and catalog entries |
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Deneb Algedi , also Deneb al Giedi (from Arabic ذنب الجدي, DMG ḏanab al-ǧady 'tail of the billy goat') or Scheddi is the proper name of the star Delta Capricorni (δ Cap) in the constellation Capricorn . Deneb Algedi is an eclipse variable of the Algol type , its apparent brightness fluctuates with a period of 1.0228 days between 2.81 and 3.05 mag, making it the brightest star in the constellation. It's just under 39 light years away.
The main star of the system is a white giant star with 1.85 times the diameter, 1.5 times the mass and 8.5 times the luminosity of the sun . Its companion may be an orange dwarf star 1.5 times the diameter and 0.6 times the mass of the Sun, orbiting it at a close distance of about 4 million km (three times the radius of the main star). It is about 40 times less luminous than the main star.
Scientific research
The spectrum of the star shows peculiarities according to which it was classified as an abnormal metal line star (Am star). It shows metal lines like an F0 star, Balmer series hydrogen lines like an F1 V star, and calcium lines like an A4 star. A value of 93 km / s was found for the projected equatorial rotation speed v ∙ sin i .
Individual evidence
- ^ A b VizieR: Hipparcos, the New Reduction (van Leeuwen, 2007) - The Astrometric Catalog
- ↑ a b c VizieR: Stellar Photometry in Johnson's 11-color system (Ducati, 2002)
- ↑ a b c VizieR: NStars project: The southern sample. I. (Gray +, 2006)
- ↑ a b VizieR: Chromospherically active binaries (Karatas +, 2004)
- ^ VizieR: Semi-detached eclipsing binaries (Surkova +, 2004)
- ^ HA Abt, NI Morrell: The relation between rotational velocities and spectral peculiarities among A-type stars. In: The Astrophysical Journal Supplement Series. Vol. 99, 1995, doi: 10.1086 / 192182 , pp. 135-172 ( bibcode : 1995ApJS ... 99..135A ).