HD 106906

HD 106906 is a binary star^[6] system in the southern constellation of Crux. It is too faint to be visible to the naked eye, having a combined apparent visual magnitude of 7.80.^[2] The distance to this system is approximately 337 light years based on parallax, and it is receding from the Sun with a radial velocity of +10 km/s.^[2] It is a member of the Lower Centaurus–Crux group of the Scorpius–Centaurus OB association of co-moving stars.^[4]

HD 106906

Star map shows star position on the northern edge of the constellation Crux
Observation data Epoch J2000.0      Equinox J2000.0
Constellation	Crux
Right ascension	12h 17m 53.191430s[1]
Declination	−55° 58′ 31.8904″[1]
Apparent magnitude (V)	7.80[2]
Characteristics
Spectral type	F5 V[3]
B−V color index	0.458±0.003[2]
Astrometry
Radial velocity (Rv)	+10.2±1.7[2] km/s
Proper motion (μ)	RA: −39.014[1] mas/yr Dec.: −12.872[1] mas/yr
Parallax (π)	9.6774 ± 0.0429 mas[1]
Distance	337 ± 1 ly (103.3 ± 0.5 pc)
Absolute magnitude (MV)	2.99[2]
Details
Radius	2.03+0.11 −0.10[1] R☉
Luminosity	6.56±0.04[1] L☉
Temperature	6,484+157 −168[1] K
Metallicity [Fe/H]	−0.04±0.08[2] dex
Age	13±2[4] Myr
Other designations
CD−55°4537, HD 106906, HIP 59960, SAO 239819, 2MASS J12175319-5558319[5]
Database references
SIMBAD	data

This is a double-lined spectroscopic binary system consisting of two F-type main-sequence stars with similar masses and a matching stellar classification of F5 V.^[6] Their orbital period is less than 100 days.^[4]

Planetary system

Edge-on disc of gas and dust present around the binary star system HD 106906

A distant circumbinary planet—HD 106906 b—is orbiting the pair at a projected separation of 732±30 AU with a period of at least 3,000 years. An infrared excess around the binary is coming from a circumstellar debris disk that is being viewed edge-on. This has a pronounced asymmetrical shape, extending 120 AU on the east side and out to 550 AU to the west.^[4] Planetary orbit is inclined to the debris disk by 39⁺²⁰
₋₁₅ degrees, and planet itself is visible nearly pole-on, having a large axial tilt.^[7]

The HD 106906 planetary system^[8]

Companion (in order from star)	Mass	Semimajor axis (AU)	Orbital period (years)	Eccentricity	Inclination	Radius
debris disk	65–550 AU				84.65 ± 0.35°	—
b	11 ± 2 MJ	~732 ± 30 AU	> 3000	—	64°	1.54 +0.04 −0.05[9] RJ

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. Houk, Nancy; Cowley, A. P. (1979), Michigan catalogue of two-dimensional spectral types for the HD stars, vol. 1, Ann Arbor, Michigan: Dept. of Astronomy, University of Michigan, Bibcode:1978mcts.book.....H.
4. Rodet, L.; et al. (June 2017), "Origin of the wide-orbit circumbinary giant planet HD 106906. A dynamical scenario and its impact on the disk", Astronomy & Astrophysics, 602: 15, arXiv:1703.01857, Bibcode:2017A&A...602A..12R, doi:10.1051/0004-6361/201630269, S2CID 119424481, A12.
5. "HD 106906". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2020-01-30.
6. Lagrange, A. -M.; et al. (February 2016), "A narrow, edge-on disk resolved around HD 106906 with SPHERE", Astronomy & Astrophysics, 586: 6, arXiv:1510.02511, Bibcode:2016A&A...586L...8L, doi:10.1051/0004-6361/201527264, S2CID 4812512, L8.
7. Bryan, Marta L.; Chiang, Eugene; Morley, Caroline V.; Mace, Gregory N.; Bowler, Brendan P. (2021), "Obliquity Constraints on the Planetary-mass Companion HD 106906 b", The Astronomical Journal, 162 (5): 217, arXiv:2108.13437, Bibcode:2021AJ....162..217B, doi:10.3847/1538-3881/ac1bb1, S2CID 237364108
8. Kalas, Paul G.; et al. (2015), "Direct Imaging of an Asymmetric Debris Disk in the Hd 106906 Planetary System", The Astrophysical Journal, 814 (1): 32, arXiv:1510.02747, Bibcode:2015ApJ...814...32K, doi:10.1088/0004-637X/814/1/32, S2CID 59575201
9. Bryan, Marta L.; Ginzburg, Sivan; Chiang, Eugene; Morley, Caroline; Bowler, Brendan P.; Xuan, Jerry W.; Knutson, Heather A. (2020-12-01). "As the Worlds Turn: Constraining Spin Evolution in the Planetary-mass Regime". The Astrophysical Journal. 905 (1): 37. arXiv:2010.07315. Bibcode:2020ApJ...905...37B. doi:10.3847/1538-4357/abc0ef. ISSN 0004-637X.