HD 210550 (HIP 109275)

HD 210550 is a white star in the constellation Cepheus. At 808 light years away, it shines at an apparent visual magnitude of 7.86. It is moving through the Galaxy at a speed of 14.7 km/s relative to the Sun.

Sky position: RA 22h 8.3m, Dec +69° 58.9'

Common designations: HD 210550, Gaia DR3 2223552470914871040, HIP 109275

HD 210550 has the spectral type A0. A-type stars are white stars with surface temperatures of roughly 7,500 to 10,000 K. Their spectra are dominated by strong hydrogen lines, and many of them rotate rapidly.

How to find HD 210550 in the sky

HD 210550 lies in Cepheus. With a declination of +69° 58.9', it is visible from the entire Northern Hemisphere and from the Southern Hemisphere down to about latitude 20° S. Observers poleward of latitude 20° N see it as circumpolar: it never sets. It is just beyond naked-eye visibility; binoculars will show it easily. 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 HD 210550

Astrometry and spectroscopy

Right Ascension (J2000)	332.07174605° (22h 8.3m)
Declination (J2000)	69.98231937° (+69° 58.9')
Galactic Longitude	109.74533849°
Galactic Latitude	11.40681130°
Proper motion RA	10.86 mas/yr
Proper motion Dec	3.72 mas/yr
Parallax	4.04 ± 0.04 mas
Spectral Type	A0
Radial Velocity	-5.90 km/s

Photometry

Band	Magnitude	Abs. Mag.
B	7.88	0.91
V	7.86	0.89
J	7.75	0.78
H	7.82	0.85
K	7.79	0.82

Colour index B-V: +0.02

Derivations

Heliocentric distance: 247.75 pc (808 light years) (0.9% margin of error)
Absolute visual magnitude: 0.89
Transverse velocity: 13.5 km/s
Space velocity relative to the Sun: 14.7 km/s
Galactic position (X, Y, Z): -82.0 pc, 228.6 pc, 49.0 pc
Galactic velocity (U, V, W): -10.4 km/s, -9.0 km/s, -5.1 km/s

Data: Extended Hipparcos Compilation (XHIP) and SIMBAD.