Delta Capricorni
Binary star in the constellation Capricornus / From Wikipedia, the free encyclopedia
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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.
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Capricornus |
Right ascension | 21h 47m 02.44424s[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 (Rv) | −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 (MV) | +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 | |
Database references | |
SIMBAD | data |
Delta Capricorni is 2.6 degrees south of the ecliptic and can be occulted by the Moon, and (rarely) by planets.[16]