Delta Cephei
Binary star system in the constellation Cepheus / From Wikipedia, the free encyclopedia
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For the variable star type, see Delta Cephei variable. For the general class of variable stars, see Cepheid variable.
Delta Cephei (δ Cep, δ Cephei) is a quadruple star system[4] located approximately 887 light-years away in the northern constellation of Cepheus, the King. At this distance, the visual magnitude of the star is diminished by 0.23 as a result of extinction caused by gas and dust along the line of sight.[5] It is the prototype of the Cepheid variable stars that undergo periodic changes in luminosity.
Quick Facts Apparent magnitude (V), Characteristics ...
Observation data Epoch J2000.0 Equinox J2000.0 | |
---|---|
Constellation | Cepheus |
δ Cep A | |
Right ascension | 22h 29m 10.26502s[1] |
Declination | +58° 24′ 54.7139″[1] |
Apparent magnitude (V) | 4.07 (3.48–4.37) / 7.5 |
δ Cep C | |
Right ascension | 22h 29m 09.248s[1] |
Declination | +58° 24′ 14.76″[1] |
Apparent magnitude (V) | 6.3 |
Characteristics | |
Spectral type | F5Ib-G1Ib[2] + B7-8[3] |
U−B color index | 0.36 |
B−V color index | 0.60 |
Variable type | Cepheid |
Astrometry | |
Radial velocity (Rv) | -16.8[4] km/s |
Proper motion (μ) | RA: +15.35[1] mas/yr Dec.: +3.52[1] mas/yr |
Parallax (π) | 3.77 ± 0.16 mas[1] |
Distance | 887 ± 26 ly (272 ± 8[5][6] pc) |
Absolute magnitude (MV) | –3.47 ± 0.10 (–3.94 - –3.05)[5] |
Details | |
δ Cep A | |
Mass | 4.5 ± 0.3[7] M☉ |
Radius | 44.5[7] R☉ |
Luminosity | ~2000[7] L☉ |
Temperature | 5,500–6,800[8] K |
Metallicity [Fe/H] | +0.08[9] dex |
Rotational velocity (v sin i) | 9[10] km/s |
Age | ~100 Myr |
δ Cep B[4] | |
Mass | 0.2 - 1.2 M☉ |
Orbit[4] | |
Primary | δ Cep A |
Companion | δ Cep B |
Period (P) | 6.03 yr |
Eccentricity (e) | 0.647 |
Semi-amplitude (K1) (primary) | 1.509 ± 0.2 km/s |
Other designations | |
Database references | |
SIMBAD | data |
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