Delta Cephei, a yellow-white supergiant star in Cepheus
Delta Cephei is a yellow-white supergiant star in the constellation Cepheus. At 917 light years away, it shines at an apparent visual magnitude of 3.75.
Delta Cephei (HIP 110991)
Delta Cephei is a yellow-white supergiant star in the constellation Cepheus. At 917 light years away, it shines at an apparent visual magnitude of 3.75. It is moving through the Galaxy at a speed of 29.0 km/s relative to the Sun.
Sky position: RA 22h 29.2m, Dec +58° 24.9'
Common designations: Delta Cephei, 27 Cephei, HR 8571, HD 213306, Gaia DR3 2200153454733285248, HIP 110991
Delta Cephei has the spectral type F5Iab:+B7-8. F-type stars are yellow-white stars of about 6,000 to 7,500 K, slightly hotter and more massive than the Sun. Their hydrogen lines are weaker than in A stars and metal lines become prominent. Its luminosity class I marks it as a supergiant, among the most luminous and largest stars known.
How to find Delta Cephei in the sky
Delta Cephei lies in Cepheus. With a declination of +58° 24.9', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 32° S. Observers poleward of latitude 32° N see it as circumpolar: it never sets. It is bright enough to see with the naked eye under dark skies. It is highest in the sky at local midnight around September, which makes the weeks around that month the best time to observe it.
Tabulated data for Delta Cephei
Astrometry and spectroscopy
| Right Ascension (J2000) | 337.29276110° (22h 29.2m) |
| Declination (J2000) | 58.41519378° (+58° 24.9') |
| Galactic Longitude | 105.19431371° |
| Galactic Latitude | 0.53059789° |
| Proper motion RA | 14.56 mas/yr |
| Proper motion Dec | 3.24 mas/yr |
| Parallax | 3.56 ± 0.15 mas |
| Spectral Type | F5Iab:+B7-8 |
| Radial Velocity | -21.15 km/s |
Photometry
| Band | Magnitude | Abs. Mag. |
|---|---|---|
| U | 4.71 | -2.54 |
| B | 4.35 | -2.90 |
| V | 3.75 | -3.50 |
| I | 3.22 | -4.03 |
| J | 2.87 | -4.38 |
| H | 2.61 | -4.64 |
| K | 2.35 | -4.89 |
Colour index B-V: +0.60
Derivations
- Heliocentric distance: 281.29 pc (917 light years) (4.1% margin of error)
- Absolute visual magnitude: -3.50
- Transverse velocity: 19.9 km/s
- Space velocity relative to the Sun: 29.0 km/s
- Galactic position (X, Y, Z): -73.7 pc, 271.4 pc, 2.6 pc
- Galactic velocity (U, V, W): -12.7 km/s, -25.3 km/s, -6.6 km/s
Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.