HD 196885

HD 196885

Location of HD 196885 (circled in red)
Observation data Epoch J2000       Equinox J2000
Constellation	Delphinus
Right ascension	20h 39m 51.87484s [1]
Declination	+11° 14′ 58.7002″ [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: +71.915 mas/yr [1] Dec.: +89.318 mas/yr [1]
Parallax (π)	29.4076±0.0272  mas [1]
Distance	110.9 ± 0.1  ly (34.00 ± 0.03  pc)
Absolute magnitude  (MV)	3.76 [2]
Orbit [5] : 7
Primary	HD 196885 A
Companion	HD 196886 B
Period (P)	69.045+0.533 −0.111  yr
Semi-major axis (a)	19.778+0.108 −0.019  AU
Eccentricity (e)	0.417+0.001 −0.004
Inclination (i)	120.427°
Longitude of the node (Ω)	79.150°
Periastron epoch (T)	1982.886 AD
Argument of periastron (ω) (secondary)	231.464°
Details [5]
A
Mass	1.3±0.1  M☉
Radius	1.35±0.10 [6]   R☉
Luminosity	2.611±0.007 [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 [7]
Rotational velocity (v sin i)	7.3±1.5 [7]  km/s
Age	1.5—3.5  Gyr
B
Mass	0.45±0.01  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 [8]
Database references
SIMBAD	data
Exoplanet Archive	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-year eccentric orbit. The primary star has one known planet. ^[5]

Stellar properties

HD 196885 A (center) and B (top left) imaged by SPHERE

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. ^[1] 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. ^{[9] [4]} It has a class in the range M1V to M3V ^[4] with 51% of the Sun's mass. ^[5]

The star BD+10 4351B, located 192 arcseconds away from HD 196885, was once thought to be a possible third component of the system, ^[10] but Gaia astrometry shows a smaller parallax, indicating that it is an unrelated background star. ^[11]

Planetary system

In 2004, an exoplanet, HD 196885 Ab, was announced to be orbiting the star HD 196885 A in a 386-day orbit. ^[12] Follow-up work published in 2008 did not confirm the original candidate but instead found evidence of a planet in a 3.63 years orbit. ^[7] Perturbation by the secondary star in this system may have driven the planet into a high inclination orbit. ^[13] The planetary existence was confirmed and parameters were refined by 2022. ^[5]

The HD 196885 planetary system ^{[5] : 7}

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
b	3.394+0.702 −0.264  MJ	2.383+0.002 −0.004	3.485+0.001 −0.016	0.444+0.013 −0.005	143.041+6.572 −4.582 °	—

See also

• Epsilon Reticuli
• GJ 3021

References

1. 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.
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. Chauvin, G.; Videla, M.; et al. (July 2023). "Chasing extreme planetary architectures. I. HD 196885 Ab, a super-Jupiter dancing with two stars?". Astronomy & Astrophysics . 675: A114. arXiv: 2211.00994 . Bibcode:2023A&A...675A.114C. doi: 10.1051/0004-6361/202244502 .
6. Ghezzi, L.; Cunha, K.; et al. (September 2010). "Stellar Parameters and Metallicities of Stars Hosting Jovian and Neptunian Mass Planets: A Possible Dependence of Planetary Mass on Metallicity". The Astrophysical Journal . 720 (2): 1290–1302. arXiv: 1007.2681 . Bibcode:2010ApJ...720.1290G. doi: 10.1088/0004-637X/720/2/1290 .
7. 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.
8. "HD 196885". SIMBAD . Centre de données astronomiques de Strasbourg . Retrieved 2020-08-08.
9. 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.
10. "HD 196885 A page". Geneva Observatory. Archived from the original on 2008-05-09. Retrieved 2008-08-19.
11. "TYC 1096-637-1". SIMBAD . Centre de données astronomiques de Strasbourg.
12. "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.
13. 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.