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HD 103197 is a star with a planetary companion in the southern constellation of Centaurus. It has an apparent visual magnitude of 9.40,[2] which is too faint to be viewed with the naked eye. Based on parallax measurements, HD 103197 is located at a distance of 187 light years from the Sun. It is drifting closer with a radial velocity of −4.6 km/s.[1]

HD 103197

Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Centaurus
Right ascension	11h 52m 52.97822s[1]
Declination	–50° 17′ 34.1592″[1]
Apparent magnitude (V)	9.40[2]
Characteristics
Spectral type	K1V(p)[3]
Apparent magnitude (B)	10.26[2]
Apparent magnitude (J)	7.916±0.023[2]
Apparent magnitude (H)	7.600±0.051[2]
Apparent magnitude (K)	7.426±0.027[2]
B−V color index	0.860±0.023[2]
Astrometry
Radial velocity (Rv)	−4.55±0.21[1] km/s
Proper motion (μ)	RA: –80.938[1] mas/yr Dec.: +7.188[1] mas/yr
Parallax (π)	17.4700 ± 0.0294 mas[1]
Distance	186.7 ± 0.3 ly (57.24 ± 0.10 pc)
Absolute magnitude (MV)	5.79[2]
Details
Mass	0.90[4] M☉
Radius	0.95±0.02[1] R☉
Luminosity	0.566+0.002 −0.001[1] L☉
Surface gravity (log g)	4.40±0.11[4] cgs
Temperature	5,303±58[4] K
Metallicity [Fe/H]	0.21±0.04[4] dex
Rotation	51±5 d[4]
Rotational velocity (v sin i)	0.602[5] km/s
Age	4.872±4.294[5] Gyr
Other designations
CD−49°6573, HD 103197, HIP 57931, PPM 769972
Database references
SIMBAD	data
Exoplanet Archive	data
Extrasolar Planets Encyclopaedia	data

This is a K-type main-sequence star with a stellar classification of K1V(p). In 1978, N. Houk noted that the cores of the star's H and K lines are weakly in emission; hence the 'p' code indicating a spectral peculiarity.[3] The star is an estimated five billion years old with a projected rotational velocity of approximately 0.6 km/s[5] and it appears to be very inactive. It has 90% of the mass and 95% of the radius of the Sun. Its metal content is five-eighths greater than in the Sun.[4]

In 2009, a gas giant exoplanet companion was discovered using the radial velocity method. This object is orbiting the host star at a distance of 0.249 AU (37.2 Gm) and a period of 47.84 d, with what is assumed to be a circular orbit.[4]

The HD 103197 planetary system[4]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥31.2 ± 2.0 M🜨	0.249 ± 0.004	47.84 ± 0.03	0.0(fixed)	—	—

See also

• List of extrasolar planets

References

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