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HD 59686 is a binary star system in the northern constellation of Gemini. It is visible to the naked eye as a dim point of light with an apparent visual magnitude of +5.45. The distance to this system is approximately 292 light years based on parallax, but it is drifting closer with a radial velocity of −34 km/s.

This is a single-lined spectroscopic binary system with an orbital period of 32.0 years and a high eccentricity of 0.73. The visible component is an aging giant star with a stellar classification of K2III, meaning it has ceased fusing hydrogen in its core and on its way to becoming a red giant. The stellar radius is very large: 11.2 times that of the Sun. The star is around 2.7 billion years old with 1.4 times the mass of the Sun. It is radiating 58 times the luminosity of the Sun from its enlarged photosphere at an effective temperature of 4,670 K.

The secondary component has a minimum mass 53% that of the Sun, which indicates it must be a star rather than a brown dwarf or a planet.

Planetary system

In November 2003, a planet was announced orbiting the giant star. A doppler spectrometer was used to look for effects on the star caused by the gravitational tug of the orbiting planet. Using the amplitude from the radial velocity method, he calculated the planetary mass as 5.25 Jupiter masses and with period 303 days. However that mass is only a minimum because the inclination of the orbit is not known. Using the stellar mass and period, he calculated the semimajor axis as 0.911 astronomical units. He found that the shape of the stellar wobble is circular, implying that the planet has zero eccentricity.

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. ^ Adams, Walter S.; Joy, Alfred H.; Humason, Milton L.; Brayton, Ada Margaret (1935), "The Spectroscopic Absolute Magnitudes and Parallaxes of 4179 Stars", Astrophysical Journal, 81: 187, Bibcode:1935ApJ....81..187A, doi:10.1086/143628.
4. ^ Ortiz, Mauricio; et al. (October 2016), "Precise radial velocities of giant stars. IX. HD 59686 Ab: a massive circumstellar planet orbiting a giant star in a 13.6 au eccentric binary system", Astronomy & Astrophysics, 595: 14, arXiv:1608.00963, Bibcode:2016A&A...595A..55O, doi:10.1051/0004-6361/201628791, S2CID 26289447, A55.
5. ^ Jofré, E.; et al. (2015), "Stellar parameters and chemical abundances of 223 evolved stars with and without planets", Astronomy and Astrophysics, 574: A50, arXiv:1410.6422, Bibcode:2015A&A...574A..50J, doi:10.1051/0004-6361/201424474, S2CID 53666931.
6. "HD 59686". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2019-01-06.
7. Trifonov, Trifon; et al. (April 2018), "Dynamical Analysis of the Circumprimary Planet in the Eccentric Binary System HD 59686", The Astronomical Journal, 155 (4): 14, arXiv:1803.01434, Bibcode:2018AJ....155..174T, doi:10.3847/1538-3881/aab439, S2CID 119487750, 174.
8. Mitchell, D.; et al. (2003), "Four Substellar Companions Found Around Nearby K Giant Stars", Bulletin of the American Astronomical Society, 35: 1234, Bibcode:2003AAS...203.1703M.

External links

• "HD 59686". Extrasolar Planets Encyclopaedia. Archived from the original on July 2, 2007.

v t e Constellation of Gemini
List of stars in Gemini Gemini in Chinese astronomy
Stars	Bayer α (Castor) β (Pollux) γ (Alhena) δ (Wasat) ε (Mebsuta) ζ (Mekbuda) η (Propus) θ ι κ λ μ (Tejat) ν ξ (Alzirr) ο (Jishui) π ρ σ τ υ φ χ ω Flamsteed 1 3 6 25 30 37 38 (e) 57 (A) 64 (b) 65 (b) 74 (f) 81 (g) Variable R U TV BG DM DN OU WY V429 HR 2877 HD 44780 50554 63433 260655 Other 2MASS 0727+1710 CXOU J061705.3+222127 Geminga Gliese 251 HAT-P-20 HAT-P-24 HAT-P-33 LB-1 PSR J0659+1414 WD J0651+2844 WISEP J060738.65+242953.4
Exoplanets HAT-P-24b HAT-P-50b HD 50554 b HD 59686 Ab Pollux b τ Geminorum b
Star clusters	NGC 2129 2158 2266 2277 2355 2420 Other Koposov 2 Messier 35
Nebulae IC 443 IC 444 Medusa Nebula NGC 2371-2 NGC 2392
Galaxies	NGC 2291 2294 2357 Other 2MASX J07322028+3138009 IC 485 PKS 0735+178
Astronomical events GRB 070125
Category

• K-type giants
• Planetary systems with one confirmed planet
• Spectroscopic binaries
• Gemini (constellation)
• Durchmusterung objects
• Henry Draper Catalogue objects
• Hipparcos objects
• Bright Star Catalogue objects