Delta Capricorni

δ Capricorni
	Location of δ Capricorni (circled)
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Capricornus
Right ascension	21h 47m 02.44424s
Declination	−16° 07′ 38.2335″
Apparent magnitude (V)	2.81 (2.81 (- 2.90) - 3.05)
Characteristics
Spectral type	A7m III (kA5hF0mF2III)
U−B color index	+0.07
B−V color index	+0.31
Variable type	Eclipsing binary (Algol-type)
Astrometry
Radial velocity (Rv)	−6.3 km/s
Proper motion (μ)	RA: +261.70 mas/yr ; Dec.: −296.70 mas/yr
Parallax (π)	84.27 ± 0.19 mas
Distance	38.70 ± 0.09 ly ; (11.87 ± 0.03 pc)
Absolute magnitude (MV)	+2.48
Orbit
Primary	δ Cap Aa
Companion	δ Cap Ab
Period (P)	1.0227683 days
Eccentricity (e)	0 (assumed)
Inclination (i)	72.5°
Periastron epoch (T)	2,448,105.793 ± 0.003 HJD
Semi-amplitude (K1); (primary)	75.3 ± 1.0 km/s
Details
δ Cap Aa
Mass	2.0 M☉
Radius	1.91 R☉
Luminosity	8.5 L☉
Surface gravity (log g)	3.66 cgs
Temperature	7,301 K
Metallicity [Fe/H]	–0.13 dex
Rotational velocity (v sin i)	105 km/s
δ Cap Ab
Mass	0.73 M☉
Radius	0.9 R☉
Temperature	4,500 K
Other designations
	Deneb Algedi, Deneb Algiedi, Scheddi, δ Cap, Del Cap, 49 Capricorni, BD−16 5943, FK5 819, GJ 837, HD 207098, HIP 107556, HR 8322, SAO 164644, ADS 15314, WDS 21470-1608
Database references
SIMBAD	data

Delta Capricorni, or δ Capricorni, is a binary star located 38.7 light-years from the Sun in the constellation of Capricornus (the Sea Goat). The system consists of an eclipsing binary,^[12] Delta Capricorni A, and two visual companions that are over 10 magnitudes fainter, labeled B and C.^[13] Delta Capricorni A's two components are designated Delta Capricorni Aa (formally named Deneb Algedi /ˌdɛnɛb ælˈdʒiːdiː/, the traditional name of the system)^[14]^[15] and Ab. The primary star, Aa, is a white giant and the combined light of Aa and Ab makes it the brightest star in the constellation.

Delta Capricorni is 2.6 degrees south of the ecliptic and can be occulted by the Moon, and (rarely) by planets.^[16]

^ ^a ^b ^c ^d ^e Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aaa446_2_785 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference gcvs was invoked but never defined (see the help page).
^ Cite error: The named reference aj126_4_2048 was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference aj79_1290 was invoked but never defined (see the help page).
^ Cite error: The named reference gcsrv was invoked but never defined (see the help page).
^ ^a ^b Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e ^f Cite error: The named reference jrasc86_2_99 was invoked but never defined (see the help page).
^ ^a ^b ^c Cite error: The named reference apj658_2_1264 was invoked but never defined (see the help page).
^ Cite error: The named reference aaa393_897 was invoked but never defined (see the help page).
^ Cite error: The named reference SIMBAD was invoked but never defined (see the help page).
^ Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).
^ "Washington Double Star Catalog". United States Naval Observatory. Archived from the original on 14 February 2011. Retrieved 2 January 2018.
^ Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.
^ "Naming Stars". IAU.org. Retrieved 16 December 2017.
^ Herr, Richard B. (April 1969). "Identification List of Spectroscopic and Eclipsing Binaries Subject to Occultations by the Moon". Publications of the Astronomical Society of the Pacific. 81 (479): 105. Bibcode:1969PASP...81..105H. doi:10.1086/128748. S2CID 123513287.

[aaa474_2_653-1] Cite error: The named reference aaa474_2_653 was invoked but never defined (see the help page).

[aaa446_2_785-2] Cite error: The named reference aaa446_2_785 was invoked but never defined (see the help page).

[gcvs-3] Cite error: The named reference gcvs was invoked but never defined (see the help page).

[aj126_4_2048-4] Cite error: The named reference aj126_4_2048 was invoked but never defined (see the help page).

[aj79_1290-5] Cite error: The named reference aj79_1290 was invoked but never defined (see the help page).

[gcsrv-6] Cite error: The named reference gcsrv was invoked but never defined (see the help page).

[Anderson2012-7] Cite error: The named reference Anderson2012 was invoked but never defined (see the help page).

[jrasc86_2_99-8] ^ ^a ^b ^c ^d ^e ^f Cite error: The named reference jrasc86_2_99 was invoked but never defined (see the help page).

[apj658_2_1264-9] Cite error: The named reference apj658_2_1264 was invoked but never defined (see the help page).

[aaa393_897-10] Cite error: The named reference aaa393_897 was invoked but never defined (see the help page).

[SIMBAD-11] Cite error: The named reference SIMBAD was invoked but never defined (see the help page).

[mnras389_2_869-12] Cite error: The named reference mnras389_2_869 was invoked but never defined (see the help page).

[WDS-13] "Washington Double Star Catalog". United States Naval Observatory. Archived from the original on 14 February 2011. Retrieved 2 January 2018.

[Kunitzsch-14] Kunitzsch, Paul; Smart, Tim (2006). A Dictionary of Modern star Names: A Short Guide to 254 Star Names and Their Derivations (2nd rev. ed.). Cambridge, Massachusetts: Sky Pub. ISBN 978-1-931559-44-7.

[IAU-LSN-15] "Naming Stars". IAU.org. Retrieved 16 December 2017.

[16] Herr, Richard B. (April 1969). "Identification List of Spectroscopic and Eclipsing Binaries Subject to Occultations by the Moon". Publications of the Astronomical Society of the Pacific. 81 (479): 105. Bibcode:1969PASP...81..105H. doi:10.1086/128748. S2CID 123513287.

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Observation data Epoch J2000.0 Equinox J2000.0
Location of δ Capricorni (circled)
Constellation	Capricornus
Right ascension	21^h 47^m 02.44424^s^[1]
Declination	−16° 07′ 38.2335″^[1]
Apparent magnitude (V)	2.81^[2] (2.81 (- 2.90) - 3.05)^[3]
Characteristics
Spectral type	A7m III^[2] (kA5hF0mF2III)^[4]
U−B color index	+0.07^[5]
B−V color index	+0.31^[5]
Variable type	Eclipsing binary (Algol-type)^[3]
Astrometry

Radial velocity (R_v)	−6.3^[6] km/s
Proper motion (μ)	RA: +261.70^[1] mas/yr Dec.: −296.70^[1] mas/yr
Parallax (π)	84.27 ± 0.19 mas^[1]
Distance	38.70 ± 0.09 ly (11.87 ± 0.03 pc)
Absolute magnitude (M_V)	+2.48^[7]

Orbit^[8]
Primary	δ Cap Aa
Companion	δ Cap Ab
Period (P)	1.0227683 days
Eccentricity (e)	0 (assumed)
Inclination (i)	72.5°
Periastron epoch (T)	2,448,105.793 ± 0.003 HJD
Semi-amplitude (K₁) (primary)	75.3 ± 1.0 km/s
Details
δ Cap Aa
Mass	2.0^[8] `M`_☉
Radius	1.91^[8] `R`_☉
Luminosity	8.5^[7] `L`_☉
Surface gravity (log g)	3.66^[9] cgs
Temperature	7,301^[9] K
Metallicity [Fe/H]	–0.13^[9] dex
Rotational velocity (v sin i)	105^[10] km/s
δ Cap Ab
Mass	0.73^[8] `M`_☉
Radius	0.9^[8] `R`_☉
Temperature	4,500^[8] K
Other designations
Deneb Algedi, Deneb Algiedi, Scheddi, δ Cap, Del Cap, 49 Capricorni, BD−16 5943, FK5 819, GJ 837, HD 207098, HIP 107556, HR 8322, SAO 164644, ADS 15314, WDS 21470-1608^[11]
Database references
SIMBAD	data