HD 196885

HD 196885

Observation data Epoch J2000      Equinox J2000
Constellation	Delphinus
Right ascension	20^h 39^m 51.87531^s[1]
Declination	+11° 14′ 58.7029″[1]
Apparent magnitude (V)	6.39[2]
Characteristics
Evolutionary stage	main-sequence star
Spectral type	F8V[3] + M1±1V[4]
B−V color index	0.559±0.006[2]
Astrometry
Radial velocity (Rv)	−30.13±0.09[2] km/s
Proper motion (μ)	RA: +71.470±0.066[1] mas/yr Dec.: +89.165±0.076[1] mas/yr
Parallax (π)	29.4076 ± 0.0272 mas[5]
Distance	110.9 ± 0.1 ly (34.00 ± 0.03 pc)
Absolute magnitude (MV)	3.76[2]
Orbit[6]
Primary	HD 196885 A
Companion	HD 196886 B
Period (P)	72.06 ± 4.59 yr
Semi-major axis (a)	21.00 ± 0.86 AU
Eccentricity (e)	0.42 ± 0.03
Inclination (i)	116.8 ± 0.7°
Longitude of the node (Ω)	79.150°
Periastron epoch (T)	1982.886 AD
Argument of periastron (ω) (secondary)	231.464°
Details[6]
A
Mass	1.3 ± 0.1 M☉
Radius	1.45+0.02 −0.05^[citation needed] R☉
Luminosity	2.695±0.006[1] L☉
Surface gravity (log g)	4.46±0.02 cgs
Temperature	6,340±39 K
Metallicity [Fe/H]	0.29±0.05 dex
Rotation	15 days^[citation needed]
Rotational velocity (v sin i)	7.3±1.5^[citation needed] km/s
Age	1.5—3.5 Gyr
B
Mass	0.45±0.01[6] M☉
Other designations
BD+10° 4351, GC 28784, HD 196885, HIP 101966, HR 7907, SAO 106360, WDS J20399+1115, GCRV 12946, GSC 01092-01778, 2MASS J20395188+1114588[7]
Database references
SIMBAD	data

HD 196885 is a binary star system in the northern constellation of Delphinus. It comprises a pair of stars HD 196885 A and HD 196885 B on a 69-years eccentric orbit.^[6]

The primary star is near the lower limit of visibility to the naked eye with an apparent visual magnitude of 6.39.^[2] It is located at a distance of 110.9 light years from the Sun.^[5] It is drifting closer with a radial velocity of −30 km/s, and is expected to come to within 52.5 light-years in 836,000 years.^[2]

The secondary, component B, is a red dwarf star separated by 0.6 arcseconds from the primary star that was discovered in 2006 with NaCo at VLT.^[8][4] It has a class in the range M1V to M3V^[4] with 51% of the Sun's mass.^[6]

The star BD+10 4351B, located 192 arcseconds away from HD 196885 is located at the same distance and may be a physically bound companion star, in which case HD 196885 is a trinary system.^[9] If it is bound, then the separation is at least 6,600 AU (the separation along the line-of-sight is unknown, so this value represents a lower limit on the true separation).^{[citation needed]}

Planetary system

In 2004, a planet was announced to be orbiting the star HD 196885 A in a 386-day orbit.^[10] Follow-up work published in 2008 did not confirm the original candidate but instead found evidence of a planet in a 3.63 years.^[11] Perturbation by the secondary star in this system may have driven the planet into a high inclination orbit.^[12] The planetary existence was confirmed and parameters were refined by 2022.^[6]

The HD 196885 planetary system^[6]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	2.98 ± 0.05 MJ	2.6 ± 0.1	3.63 ± 0.01	0.48 ± 0.02	—	—

See also

• Epsilon Reticuli
• GJ 3021

References

1. 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.
2. 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.
3. Gray, R. O.; et al. (2001), "The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars", The Astronomical Journal, 121 (4): 2148, Bibcode:2001AJ....121.2148G, doi:10.1086/319956, S2CID 117076031
4. Chauvin, G.; et al. (2007). "Characterization of the long-period companions of the exoplanet host stars: HD 196885, HD 1237 and HD 27442". Astronomy and Astrophysics. 475 (2): 723–727. arXiv:0710.5918. Bibcode:2007A&A...475..723C. doi:10.1051/0004-6361:20067046. S2CID 16950822.
5. 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.
6. Chauvin, G.; Videla, M.; Beust, H.; Mendez, R.; Correia, A. C. M.; Lacour, S.; Tokovinin, A.; Hagelberg, J.; Bouchy, F.; Boisse, I.; Villegas, C.; Bonavita, M.; Desidera, S.; Faramaz, V.; Forveille, T.; Gallenne, A.; Haubois, X.; Jenkins, J. S.; Kervella, P.; Lagrange, A. -M.; Melo, C.; Thebault, P.; Udry, S.; Segransan, D. (2023), "Chasing extreme planetary architectures", Astronomy & Astrophysics, 675: A114, arXiv:2211.00994, doi:10.1051/0004-6361/202244502
7. "HD 196885". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-08.
8. Chauvin, G.; et al. (2006). "Probing long-period companions to planetary hosts. VLT and CFHT near infrared coronographic imaging surveys". Astronomy and Astrophysics. 456 (3): 1165–1172. arXiv:astro-ph/0606166. Bibcode:2006A&A...456.1165C. doi:10.1051/0004-6361:20054709. S2CID 15611548.
9. "HD 196885 A page". Geneva Observatory. Archived from the original on 2008-05-09. Retrieved 2008-08-19.
10. "The Planet Around HD 196885". California & Carnegie Planet Search Team (Internet Archive link). Archived from the original on 2004-12-27. Retrieved 2008-08-19.
11. Correia, A. C. M.; et al. (2008). "The ELODIE survey for northern extra-solar planets. IV. HD 196885, a close binary star with a 3.7-year planet". Astronomy and Astrophysics. 479 (1): 271–275. arXiv:0711.3343. Bibcode:2008A&A...479..271C. doi:10.1051/0004-6361:20078908. S2CID 119261807.
12. Satyal, S.; Hinse, T. C.; Quarles, B.; Noyola, J. P. (September 2014). "Chaotic dynamics of the planet in HD 196885 AB". Monthly Notices of the Royal Astronomical Society. 443 (2): 1310–1318. arXiv:1401.1268. Bibcode:2014MNRAS.443.1310S. doi:10.1093/mnras/stu1221. S2CID 119189415.