HD 65216

HD 65216 is a triple^[6] star system with two exoplanetary companions in the southern constellation of Carina. With an apparent visual magnitude of 7.97^[1] it cannot be readily seen without technical aid, but with binoculars or telescope it should be visible. The system is located at a distance of 114.7 light-years from the Sun based on parallax measurements, and is drifting further away with a radial velocity of 42.6 km/s.^[2]

HD 65216

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Carina[1]
A
Right ascension	07h 53m 41.3193s[2]
Declination	−63° 38′ 50.353″[2]
Apparent magnitude (V)	7.97[1]
B
Right ascension	07h 53m 42.3964s[3]
Declination	−63° 38′ 50.182″[3]
Apparent magnitude (V)	18.58[4]
Characteristics
Spectral type	G5V[5] + M7–8 + L2–3[6]
B−V color index	0.672±0.012[1]
Astrometry
A
Radial velocity (Rv)	42.57±0.16[2] km/s
Proper motion (μ)	RA: −123.633±0.065 mas/yr[2] Dec.: +146.578±0.073 mas/yr[2]
Parallax (π)	28.4445±0.0317 mas[2]
Distance	114.7 ± 0.1 ly (35.16 ± 0.04 pc)
Absolute magnitude (MV)	5.22[1]
B
Proper motion (μ)	RA: −119.227 mas/yr[3] Dec.: +134.271 mas/yr[3]
Parallax (π)	27.7827±0.1542 mas[3]
Distance	117.4 ± 0.7 ly (36.0 ± 0.2 pc)
Details
HD 65216 A
Mass	0.95±0.01[7] M☉
Radius	0.864±0.003[7] R☉
Luminosity	0.716±0.001[7] L☉
Surface gravity (log g)	4.53±0.01[7] cgs
Temperature	5,718±8[7] K
Metallicity [Fe/H]	−0.17[8] dex
Rotational velocity (v sin i)	1.308[8] km/s
Age	1.7±0.5[7] Gyr
Ba
Mass	0.09[4] M☉
Bb
Mass	0.08[4] M☉
Other designations
CD−63°359, HD 65216, HIP 38558, SAO 250002, WDS J07537-6339A[9]
Database references
SIMBAD	data

Stellar system

The primary of HD 65216, component A, is an ordinary G-type main-sequence star with a stellar classification of G5V.^[5] It is nearly two billion years old^[7] and is spinning with a projected rotational velocity of 1.3 km/s.^[8] The star has 95% of the mass and 86% of the radius of the Sun. It is radiating 72% of the luminosity of the Sun from its photosphere at an effective temperature of 5,718 K.^[7]

In 2008 a co-moving binary system of low mass companions were discovered at an angular separation of 7″ from the primary, which is equivalent to a projected separation of 253 AU at the distance of HD 65216. Component B is of class M7–8 (0.089 M_☉) while component C is class L2–3 (0.078 M_☉); both have a mass close to the sub-stellar limit. The pair have a projected separation of 6 AU from each other.^[6]

Planetary system

An extrasolar planet (designated as HD 65216 b) was discovered orbiting the primary in 2003.^[10] A second much more distant planet was suspected since 2013,^[11] but was discovered on a completely different orbit in 2019.^[12]

The HD 65216 planetary system^[12]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥1.295±0.062 MJ	1.301±0.020	577.6±1.328	0.27±0.02	—	—
c	≥2.03±0.11 MJ	5.75±0.09	5370±20	0.17±0.04	—	—

See also

• List of extrasolar planets