HD 240210

HD 240210 is a star in the northern constellation of Cassiopeia. It has an orange hue but is too faint to be viewed with the naked eye, having an apparent visual magnitude of 8.33.^[3] Parallax measurements provide an estimate of its distance from the Sun as approximately 1,230 light years. It is drifting further away with a radial velocity of +8.6 km/s.^[2]

HD 240210

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Cassiopeia[1]
Right ascension	23h 10m 29.22633s[2]
Declination	+57° 01′ 46.0277″[2]
Apparent magnitude (V)	8.33[3]
Characteristics
Evolutionary stage	giant[3]
Spectral type	K3III
B−V color index	1.63
Astrometry
Radial velocity (Rv)	+8.57±0.05[2] km/s
Proper motion (μ)	RA: 18.492[2] mas/yr Dec.: 6.883[2] mas/yr
Parallax (π)	2.6570±0.0349 mas[2]
Distance	1,230 ± 20 ly (376 ± 5 pc)
Absolute bolometric magnitude (Mbol)	+0.38[3]
Details
Mass	1.25±0.25[3] M☉
Radius	25.46+1.16 −0.75[2] R☉
Luminosity	152±3[2] L☉
Surface gravity (log g)	2.31±0.11[3] cgs
Temperature	4,019+60 −90[2] K
Metallicity [Fe/H]	−0.18±0.12[3] dex
Rotation	> 654 days[3]
Rotational velocity (v sin i)	< 1.0[3] km/s
Age	3.0+2.9 −1.5[4] Gyr
Other designations
BD+56°2959, HD 240210, SAO 35195, PPM 41549[5]
Database references
SIMBAD	data
Exoplanet Archive	data

This is an aging giant star with a class of K3,^[3] which has exhausted the supply of hydrogen at its core and expanded to 25^[2] times the radius of the Sun. It is around three^[4] billion years old with 1.3^[3] times the Sun's mass. The star is radiating 152 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,019 K.^[2] It is spinning slowly, with each rotation taking at least 1.8 years.^[3]

On June 10, 2009 a planet orbiting the star was discovered by Niedzielski et al. This exoplanet is a 6.9 or greater Jupiter mass planet. Evidence for additional planetary companions has been found.^[6]

The HD 240210 planetary system^[3]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥ 6.90 MJ	1.33	501.75±2.33	0.15±0.02	—	—

See also

• BD+14°4559
• BD+20°2457
• List of extrasolar planets
• John Flamsteed