HD 196885
HD 196885 is a binary star system in the northern constellation of Delphinus. It is near the lower limit of visibility to the naked eye with an apparent visual magnitude of 6.39.[2] According to its parallax of 29.24 mas, it is located at a distance of 112 light years from the Sun. 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 absolute magnitude of the system is 3.76.[2]
| Observation data Epoch J2000 Equinox J2000 | |
|---|---|
| Constellation | Delphinus |
| Right ascension | 20h 39m 51.87531s[1] |
| Declination | +11° 14′ 58.7029″[1] |
| Apparent magnitude (V) | 6.39[2] |
| Characteristics | |
| 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) | 29.2372 ± 0.0486[1] mas |
| Distance | 111.6 ± 0.2 ly (34.20 ± 0.06 pc) |
| Absolute magnitude (MV) | 3.76[2] |
| Orbit[5] | |
| 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) | 79.8±0.1° |
| Argument of periastron (ω) (secondary) | −118.1±3.1° |
| Details[6] | |
| A | |
| Mass | 1.33 M☉ |
| Radius | 1.45+0.02 −0.05[1] 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 |
| Rotational velocity (v sin i) | 7.3±1.5 km/s |
| Age | 2.0±0.5 Gyr |
| B | |
| Mass | 0.45±0.01[5] M☉ |
| Other designations | |
| Database references | |
| SIMBAD | data |
The primary, component A, is an F-type main-sequence star with a stellar classification of F8V[3] It is about two billion years old and is spinning with a projected rotational velocity, for a rotation period of around 15 days. The star has 1.33[6] times the mass of the Sun and 1.45 times the Sun's radius.[1] The metallicity of this star – what astronomers term the abundance of elements with higher atomic number than helium – is nearly double that in the Sun. It is radiating 2.7 times the luminosity of the Sun from its photosphere at an effective temperature of 6,340 K.[6]
In 2004, a planet was announced to be orbiting the star in a 386-day orbit.[8] Follow-up work published in 2008 did not confirm the original candidate but instead found evidence of a planet in a 3.63 years.[6] This object has a minimum estimated mass at least three times that of the planet Jupiter.[5] Perturbation by the secondary star in this system may have driven the planet into a high inclination orbit.[9]
The secondary, component B, is a red dwarf star separated by 0.7 arcseconds from the primary star.[10] At a distance of 112 light years, this corresponds to a separation of 24 AU between the stars.[4] Since the separation along the line-of-sight is unknown, this represents a lower limit on the true separation. The orbital elements of the pair give an orbital period of 72 years, a semimajor axis of 21 AU, and an eccentricity of 0.42.[5] It has a class in the range M1V to M3V[4] with 45% of the Sun's mass.[5]
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 triple system.[10] 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).
| Companion (in order from star) |
Mass | Semimajor axis (AU) |
Orbital period (days) |
Eccentricity | Inclination | Radius |
|---|---|---|---|---|---|---|
| b | ≥2.98±0.05 MJ | 2.6±0.1 | 1,326.0±3.7 | 0.48±0.02 | — | — |
See also
- Epsilon Reticuli
- GJ 3021
References
- 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.
- 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.
- 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
- 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.
- Chauvin, G.; et al. (2011). "Planetary systems in close binary stars: the case of HD 196885" (abstract). Astronomy and Astrophysics. 528: A8. arXiv:1009.5851. Bibcode:2011A&A...528A...8C. doi:10.1051/0004-6361/201015433. (web preprint)
- 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.
- "HD 196885". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-08-08.
- "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.
- 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.
- "HD 196885 A page". Geneva Observatory. Retrieved 2008-08-19.
