Delta Capricorni
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Observation data Epoch J2000.0 |
|
---|---|
Constellation (pronunciation) |
Capricornus |
Right ascension | 21h 47m 03s |
Declination | -16° 07′ 38″ |
Apparent magnitude (V) | 2.85 |
Characteristics | |
Spectral type | A7III |
U-B color index | 0.08 |
B-V color index | 0.30 |
Variable type | δ Sct/eclipsing binary |
Astrometry | |
Radial velocity (Rv) | -0.2 km/s |
Proper motion (μ) | RA: 263.26 mas/yr Dec.: -296.23 mas/yr |
Parallax (π) | 84.58 ± 0.88 mas |
Distance | 38.6 ± 0.4 ly (11.8 ± 0.1 pc) |
Absolute magnitude (MV) | 2.49 |
Details | |
Mass | 0.61-1.25 M☉ |
Radius | 1.64 R☉ |
Luminosity | 8.5 L☉ |
Temperature | 7,700 K |
Metallicity | ? |
Rotation | 87 km/s. |
Age | ? years |
Other designations | |
Delta Capricorni (δ Cap / δ Capricorni) is a star system about 39 light-years away in the constellation Capricornus. It also has the traditional names Deneb Algedi or Scheddi.
The traditional names are from the Arabic ذنب الجدي ðanab[u] al-jadiyy, meaning "the tail of the goat." As it represents the fishlike tail of a celestial goat, Deneb Algedi is astrologically flexible, associated with good and bad fortune alike. It was one of the fifteen Behenian stars of medieval astrology, associated with chalcedony, marjoram and the kabbalistic symbol .
Because it is near the ecliptic, δ Capricorni can be occulted by the Moon, and also (rarely) by planets.
δ Capricorni is a four-star system. The primary, δ Capricorni A is classified a white A-type giant with an apparent magnitude of +2.85. It is a spectroscopic binary whose two components are of magnitude +3.2 and +5.2, and separated by 0.0018 arcseconds. Similar to Algol (β Persei), δ Capricorni A is an eclipsing binary. Its unresolved companion orbits with δ Capricorni A around their common centre of mass every 1.022768 days, causing the brightness to drop 0.2 magnitudes during eclipses.
Two other stars are thought to orbit further out in the system. The sixteenth magnitude δ Capricorni C is one arcminute away and the thirteenth magnitude δ Capricorni D is two arcminutes away from the primary.
[edit] References
- ^ * Batten, A. H., 1961, "The spectroscopic orbit of delta Capricorni (HD 207098)", Publ. Dominion Astrophys. Obs., 11, 395-403.
- ^ Wright, Anne (2003). "The Fixed Stars: Deneb Algedi". Retrieved July 28, 2005.
- Malasan, H. L. et al, 1989, "Delta Capricorni - an evolved binary or a main-sequence binary?", Astronomical Journal, vol. 97, pp. 499-504.
[edit] External links
- Deneb Algedi by Professor Jim Kaler.
- ARICNS
- Hipparcos star catalog entry
- Alcyone emphemeris