Delta Capricorni

Delta Capricorni

Location of δ Capricorni (left center)
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	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	Delta Scuti 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	~39 ly (~11 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
Rotation	87 km/s
Other designations
Deneb Algedi, Scheddi, 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
Database references
SIMBAD	data

Delta Capricorni (δ Cap, δ Capricorni), also traditionally named Deneb Algedi and Scheddi, is a quaternary star system approximately 39 light-years away in the constellation of Capricornus (the Sea Goat). The primary star in the system is a white giant star and the combined light of its four members makes it the brightest "single" star within the constellation. The traditional names are from the Arabic ذنب الجدي ðanab al-jady, 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, Delta Capricorni can be occulted by the Moon, and also (rarely) by planets.

In Chinese, 壘壁陣 (Lěi Bì Zhèn), meaning Line of Ramparts, refers to an asterism consisting of δ Capricorni, κ Capricorni, ε Capricorni, γ Capricorni, ι Aquarii, λ Aquarii, σ Aquarii, φ Aquarii, 27 Piscium, 29 Piscium, 33 Piscium and 30 Piscium.^[1] Consequently, δ Capricorni itself is known as 壘壁陣四 (Lěi Bì Zhèn sì, English: the Fourth Star of Line of Ramparts.)^[2]

Stellar system

Delta Capricorni is a four-star system (otherwise known as a quaternary system). The primary, Delta Capricorni A, is classified a white giant star of the spectral type "A". The system is a spectroscopic binary whose two components are of magnitude +3.2 and +5.2, and separated by 0.0018 arcseconds. Similar to Algol, Delta 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 Delta Capricorni C is one arcminute away, while the thirteenth magnitude Delta δ Capricorni D is two arcminutes away from the primary.

See also

• Alpha Capricorni
• Deneb

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". Archived from the original on June 16, 2005. http://web.archive.org/web/20050616081842/http://www.winshop.com.au/annew/DenebAlgedi.html. Retrieved July 28, 2005. 
• Malasan, H. L.; et al. (1989). "Delta Capricorni – an evolved binary or a main-sequence binary?". Astronomical Journal 97: 499–504. Bibcode 1989AJ.....97..499M. doi:10.1086/114999. 

1. ^ (Chinese) 中國星座神話, written by 陳久金. Published by 台灣書房出版有限公司, 2005, ISBN 978-986-7332-25-7.
2. ^ (Chinese) 香港太空館 - 研究資源 - 亮星中英對照表, Hong Kong Space Museum. Accessed on line November 23, 2010.

External links

• "Delta Capricorni". Heavens Above. Hipparcos Star Catalog Entry. http://www.heavens-above.com/hipentry.asp?hip=107556. Retrieved 2008-06-21. 
• Kaler, Jim. "Deneb Algedi". University of Illinois. STARS. http://www.astro.uiuc.edu/~kaler/sow/denebalgedi.html. Retrieved 2008-06-21.