HAT-P-18

HAT-P-18
Observation data; Epoch J2000 Equinox J2000
Constellation	Hercules
Right ascension	17h 05m 23.1475s
Declination	+33° 00′ 44.940″
Apparent magnitude (V)	12.759
Characteristics
Spectral type	K2V
Astrometry
Radial velocity (Rv)	-11.83 km/s
Proper motion (μ)	RA: −14.002(9) mas/yr ; Dec.: −36.751(11) mas/yr
Parallax (π)	6.1863 ± 0.0093 mas
Distance	527.2 ± 0.8 ly ; (161.6 ± 0.2 pc)
Details
Mass	0.750+0.015; −0.014 M☉
Radius	0.7202+0.0095; −0.01 R☉
Luminosity	0.27±0.04 L☉
Surface gravity (log g)	4.599±0.013 cgs
Temperature	4835+39; −35 K
Metallicity	0.044+0.060; −0.051
Rotation	14.66±0.03 d
Rotational velocity (v sin i)	0.5±0.5 km/s
Age	12.4+4.4; −6.4 Gyr
Other designations
	Gaia DR2 1334573817793362560, GSC 02594-00646, 2MASS J17052315+3300450
Database references
SIMBAD	data

HAT-P-18 is a K-type main-sequence star about 530 light-years away. The star is very old and has a concentration of heavy elements similar to solar abundance.^[4] A survey in 2015 detected very strong starspot activity on HAT-P-18.^[6]

^ ^a ^b ^c ^d Cite error: The named reference Gaia DR3 was invoked but never defined (see the help page).
^ Cite error: The named reference Hartman2010 was invoked but never defined (see the help page).
^ Cite error: The named reference Wang2021 was invoked but never defined (see the help page).
^ ^a ^b ^c ^d ^e Everett, Mark E.; Howell, Steve B.; Silva, David R.; Szkody, Paula (2013), "Spectroscopy of Faint Kepler Mission Exoplanet Candidate Host Stars", The Astrophysical Journal, 771 (2): 107, arXiv:1305.0578, Bibcode:2013ApJ...771..107E, doi:10.1088/0004-637X/771/2/107, S2CID 119270620
^ Cite error: The named reference simbad was invoked but never defined (see the help page).
^ Piskorz, Danielle; Knutson, Heather A.; Ngo, Henry; Muirhead, Philip S.; Batygin, Konstantin; Crepp, Justin R.; Hinkley, Sasha; Morton, Timothy D. (2015), "Friends of Hot Jupiters. III. An Infrared Spectroscopic Search for Low-Mass Stellar Companions", The Astrophysical Journal, 814 (2): 148, arXiv:1510.08062, Bibcode:2015ApJ...814..148P, doi:10.1088/0004-637X/814/2/148, S2CID 11525988

[Gaia_DR3-1] Cite error: The named reference Gaia DR3 was invoked but never defined (see the help page).

[Hartman2010-2] Cite error: The named reference Hartman2010 was invoked but never defined (see the help page).

[Wang2021-3] Cite error: The named reference Wang2021 was invoked but never defined (see the help page).

[Everett2013-4] Everett, Mark E.; Howell, Steve B.; Silva, David R.; Szkody, Paula (2013), "Spectroscopy of Faint Kepler Mission Exoplanet Candidate Host Stars", The Astrophysical Journal, 771 (2): 107, arXiv:1305.0578, Bibcode:2013ApJ...771..107E, doi:10.1088/0004-637X/771/2/107, S2CID 119270620

[simbad-5] Cite error: The named reference simbad was invoked but never defined (see the help page).

[6] Piskorz, Danielle; Knutson, Heather A.; Ngo, Henry; Muirhead, Philip S.; Batygin, Konstantin; Crepp, Justin R.; Hinkley, Sasha; Morton, Timothy D. (2015), "Friends of Hot Jupiters. III. An Infrared Spectroscopic Search for Low-Mass Stellar Companions", The Astrophysical Journal, 814 (2): 148, arXiv:1510.08062, Bibcode:2015ApJ...814..148P, doi:10.1088/0004-637X/814/2/148, S2CID 11525988

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Observation data Epoch J2000 Equinox J2000
Constellation	Hercules
Right ascension	17^h 05^m 23.1475^s^[1]
Declination	+33° 00′ 44.940″^[1]
Apparent magnitude (V)	12.759^[2]
Characteristics
Spectral type	K2V
Astrometry

Radial velocity (R_v)	-11.83 km/s
Proper motion (μ)	RA: −14.002(9) mas/yr^[1] Dec.: −36.751(11) mas/yr^[1]
Parallax (π)	6.1863 ± 0.0093 mas^[1]
Distance	527.2 ± 0.8 ly (161.6 ± 0.2 pc)

Details^[3]

Mass	0.750^+0.015 _−0.014 `M`_☉
Radius	0.7202^+0.0095 _−0.01 `R`_☉
Luminosity	0.27±0.04^[4] `L`_☉
Surface gravity (log g)	4.599±0.013 cgs
Temperature	4835⁺³⁹ ₋₃₅ K
Metallicity	0.044^+0.060 _−0.051
Rotation	14.66±0.03 d^[4]
Rotational velocity (v sin i)	0.5±0.5^[4] km/s
Age	12.4^+4.4 _−6.4^[4] Gyr

Other designations
Gaia DR2 1334573817793362560, GSC 02594-00646, 2MASS J17052315+3300450^[5]
Database references
SIMBAD	data