HD 128311

HD 128311 or HN Boötis is an orange main-sequence star located approximately 54 light-years away in the constellation of Boötes. Two extrasolar planet candidates have been detected in orbit around this star.

HD 128311
Observation data
Epoch J2000      Equinox J2000
Constellation Boötes
Right ascension  14h 36m 00.56s[1]
Declination +09° 44′ 47.5″[1]
Apparent magnitude (V) 7.51
Characteristics
Spectral type K0V
U−B color index 0.78
B−V color index 0.99
Variable type BY Dra[2]
Astrometry
Radial velocity (Rv)-9.6 ± 0.4 km/s
Proper motion (μ) RA: 204.74 ± 0.74[1] mas/yr
Dec.: -249.98 ± 0.61[1] mas/yr
Parallax (π)60.60 ± 0.83[1] mas
Distance53.8 ± 0.7 ly
(16.5 ± 0.2 pc)
Absolute magnitude (MV)8.5
Details
Mass0.8 M☉
Radius0.73 R☉
Luminosity0.221 L☉
Surface gravity (log g)41.9 g cgs
Temperature4965 K
Metallicity108%
Age0.39 Gyr
Other designations
BD+10° 2710, GC 19679, GJ 3860, GSC 00910-00165, HIP 71395, HN Boo, LTT 14312, SAO 120554.
Database references
SIMBADdata
ARICNSdata

Planetary system

In 2002, the discovery of the planet HD 128311 b was announced by Paul Butler.[3] In 2005, the discovery of a second planet HD 128311 c was announced by Steve Vogt.[4]

Most likely, the system has been formed in a very turbulent disc.[5] The authors were able to show with both analytic and numerical models that certain libration modes are readily excited by turbulence. It was initially thought that the system could have been resulted from planet planet scattering, but this is rather unlikely.

Time evolution of orbital elements in the system HD128311. This left panel in this plot shows the most likely formation scenario for the planetary system. The right panel shows the observed orbital configuration.
The HD 128311 planetary system[4]
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b >2.18 ± 0.22 MJ 1.099 ± 0.04 458.6 ± 6.8 0.25 ± 0.10 — —
c >3.21 ± 0.30 MJ 1.76 ± 0.13 928.3 ± 18 0.17 ± 0.09 — —
gollark: My phone provider will happily accept you as me if you know name, birthday and location apparently.
gollark: I guess some local Facebook cache server is still working, but unable to communicate with any backend services.
gollark: If I curl it I get a "sorry" page.
gollark: Surely it couldn't have been that hard to make the door system work without constantly querying internal stuff.
gollark: You can already play VR *goat* simulator.

See also
  • List of extrasolar planets

References
  1. van Leeuwen, F. (2007). "Validation of the new Hipparcos reduction". Astronomy and Astrophysics. 474 (2): 653–664. arXiv:0708.1752. Bibcode:2007A&A...474..653V. doi:10.1051/0004-6361:20078357. Vizier catalog entry
  2. Samus, N. N.; Durlevich, O. V.; et al. (2009). "VizieR Online Data Catalog: General Catalogue of Variable Stars (Samus+ 2007-2013)". VizieR On-line Data Catalog: B/GCVS. Originally Published in: 2009yCat....102025S. 1. Bibcode:2009yCat....102025S.
  3. Butler, R. Paul; et al. (2003). "Seven New Keck Planets Orbiting G and K Dwarfs". The Astrophysical Journal. 582 (1): 455–466. Bibcode:2003ApJ...582..455B. CiteSeerX 10.1.1.7.6988. doi:10.1086/344570.
  4. Vogt, Steven S.; et al. (2005). "Five New Multicomponent Planetary Systems". The Astrophysical Journal. 632 (1): 638–658. Bibcode:2005ApJ...632..638V. doi:10.1086/432901.
  5. Rein, Hanno; Papaloizou, J. C. B. (2009). "On the evolution of mean motion resonances through stochastic forcing: Fast and slow libration modes and the origin of HD128311". Astronomy and Astrophysics. 497 (2): 595–609. arXiv:0811.1813. Bibcode:2009A&A...497..595R. doi:10.1051/0004-6361/200811330.

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