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HD 168443
Observation data; Epoch J2000.0 Equinox J2000.0
Constellation	Serpens
Right ascension	18h 20m 03.933288s
Declination	−09° 35′ 44.614581″
Apparent magnitude (V)	6.92
Characteristics
Spectral type	G6V
B−V color index	0.724±0.014
Astrometry
Radial velocity (Rv)	−48.69±0.10 km/s
Proper motion (μ)	RA: −91.792±0.036 mas/yr ; Dec.: −223.979±0.030 mas/yr
Parallax (π)	25.5913 ± 0.0410 mas
Distance	127.4 ± 0.2 ly ; (39.08 ± 0.06 pc)
Absolute magnitude (MV)	4.198
Details
Mass	0.995±0.019 M☉
Radius	1.51±0.06 R☉
Luminosity	2.413±0.009 L☉
Surface gravity (log g)	4.07±0.06 cgs
Temperature	5,491±44 K
Metallicity [Fe/H]	+0.04±0.03 dex
Rotational velocity (v sin i)	2.20±0.50 km/s
Age	11.3+1.0; −0.8 Gyr
Other designations
	BD−09°4692, GJ 4052, HD 168443, HIP 89844, SAO 142228, LTT 7289
Database references
SIMBAD	data
Exoplanet Archive	data

HD 168443 is an ordinary yellow-hued star in the Serpens Cauda segment of the equatorial constellation of Serpens. It is known to have two substellar companions. With an apparent visual magnitude of 6.92,^[2] the star lies just below the nominal lower brightness limit of visibility to the normal human eye. This system is located at a distance of 127 light years from the Sun based on parallax,^[1] but is drifting closer with a radial velocity of −48.7 km/s.^[2]

This stellar object is a core hydrogen fusing G-type main-sequence star with a classification of G6V, although it is likely evolved^[4] with an age of around 11 billion years.^[2] It is slightly lower in mass than the Sun but has a radius that is larger by 51%. The star is spinning with a leisurely projected rotational velocity of 2.2 km/s^[4] and it has a very inactive chromosphere.^[3]^[4] It is radiating 2.4^[5] times the luminosity of the Sun from its photosphere at an effective temperature of 5,491 K.^[4]

Planetary system

HD 168443 is known to be orbited by a super-Jupiter exoplanet, discovered in 1999, and a brown dwarf, discovered in 2001. The brown dwarf takes 30 times longer to orbit the star than the planet.^[7]^[8]^[9] Both have eccentric orbits.^[4] An orbital fit to Hipparcos astrometric data suggested the brown dwarf has a mass of 34±12 M_J.^[9] A 2022 study utilizing both Hipparcos and Gaia data instead measured a true mass of 17.3 M_J for HD 168443 c, close to the minimum mass.^[10] Test simulations of massless particles orbiting in between these two bodies show that all such objects are quickly ejected within two million years. That suggests any other planetary companions would be orbiting further out from the star.^[11]

The HD 168443 planetary system^[4]^[10]
Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (days)	Eccentricity	Inclination	Radius
b	≥7.659±0.0975 $M$ _J	0.2931±0.00181	58.11247±0.0003	0.52883±0.00103	—	—
c	17.306+2.550 −0.906 $M$ _J	2.8373±0.018	1,749.83±0.57	0.2113±0.00171	91.218+22.283 −16.088°	—

References

^ ^a ^b ^c ^d ^e Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv:2208.00211. Bibcode:2023A&A...674A...1G. doi:10.1051/0004-6361/202243940. S2CID 244398875. Gaia DR3 record for this source at VizieR.
^ ^a ^b ^c ^d ^e ^f ^g Anderson, E.; Francis, Ch. (2012). "XHIP: An extended hipparcos compilation". Astronomy Letters. 38 (5): 331. arXiv:1108.4971. Bibcode:2012AstL...38..331A. doi:10.1134/S1063773712050015. S2CID 119257644.
^ ^a ^b Gray, R. O.; et al. (July 2006), "Contributions to the Nearby Stars (NStars) Project: Spectroscopy of Stars Earlier than M0 within 40 pc-The Southern Sample", The Astronomical Journal, 132 (1): 161–170, arXiv:astro-ph/0603770, Bibcode:2006AJ....132..161G, doi:10.1086/504637, S2CID 119476992
^ ^a ^b ^c ^d ^e ^f ^g ^h Pilyavsky, Genady; et al. (December 2011). "A Search for the Transit of HD 168443b: Improved Orbital Parameters and Photometry". The Astrophysical Journal. 743 (2): 8. arXiv:1109.5166. Bibcode:2011ApJ...743..162P. doi:10.1088/0004-637X/743/2/162. S2CID 13190486. 162.
^ ^a ^b Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
^ "HD 168443". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-12-06.
^ Marcy, Geoffrey W.; et al. (1999). "Two New Planets in Eccentric Orbits". The Astrophysical Journal. 520 (1): 239–247. arXiv:astro-ph/9904275. Bibcode:1999ApJ...520..239M. doi:10.1086/307451. S2CID 16827678.
^ Marcy, Geoffrey W.; et al. (2001). "Two Substellar Companions Orbiting HD 168443". The Astrophysical Journal. 555 (1): 418–425. Bibcode:2001ApJ...555..418M. doi:10.1086/321445.
^ ^a ^b Reffert, S.; Quirrenbach, A. (2006). "Hipparcos astrometric orbits for two brown dwarf companions: HD 38529 and HD 168443". Astronomy and Astrophysics. 449 (2): 699–702. Bibcode:2006A&A...449..699R. doi:10.1051/0004-6361:20054611. hdl:1887/7483.
^ ^a ^b Feng, Fabo; Butler, R. Paul; et al. (August 2022). "3D Selection of 167 Substellar Companions to Nearby Stars". The Astrophysical Journal Supplement Series. 262 (21): 21. arXiv:2208.12720. Bibcode:2022ApJS..262...21F. doi:10.3847/1538-4365/ac7e57. S2CID 251864022.
^ Barnes, Rory; Raymond, Sean N. (December 2004). "Predicting Planets in Known Extrasolar Planetary Systems. I. Test Particle Simulations". The Astrophysical Journal. 617 (1): 569–574. arXiv:astro-ph/0402542. Bibcode:2004ApJ...617..569B. doi:10.1086/423419. S2CID 12380925.

External links

"Two new planetary systems discovered" (Press release). Kamuela, Hawaii: W. M. Keck Observatory. January 9, 2001. Retrieved August 13, 2019.
"Notes for star HD 168443". Extrasolar Planets Encyclopaedia. Archived from the original on November 6, 2007. Retrieved 2008-09-08.