Delta Capricorni

From Wikipedia, the free encyclopedia

**δ Capricorni**
Observation data Equinox J2000.0
Deneb Algedi (δ) in Capricornus
Constellation	Capricornus
Right ascension	21^h 47^m 03^s
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 (R_v)	-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 (M_V)	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
Deneb Algedi, Deneb Algiedi, Scheddi, Sheddi, 49 Capricorni, GJ 837, HR 8322, BD−16°5943, HD 207098, GCTP 5258.00, SAO 164644, FK5 819, HIP 107556, GC 30491, ADS 15314, CCDM 21470-1607

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.^[1] 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.^[2]

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.