HD 128311

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HD 128311

Observation data Epoch 2000
Constellation (pronunciation)	Boötes
Right ascension	14h 36m 00.5607s
Declination	+09° 44' 47.466"
Apparent magnitude (V)	7.48
Distance	54.14 ly (18.04 pc)
Spectral type	K0V
Other designations
HIP 71395, BD+10°2710, SAO 120554, LTT 14312

HD 128311 is an orange main sequence star in the constellation Boötes. It is about 54 light years from the Sun. Two extrasolar planet candidates have been detected in orbit around this star.

[edit] HD 128311 b

HD 128311 b

Discovery
Discovered by	Butler et al.
Discovery date	2002
Detection method	Radial velocity
Orbital characteristics
Semi-major axis	1.100 ± 0.065 AU
Eccentricity	0.25 ± 0.10
Orbital period	458.6 ± 6.8 d
Angular distance	66.205 mas
Longitude of periastron	111° ± 36°
Time of periastron	2,450,211 ± 76 JD
Semi-amplitude	66.8 ± 8.7 m/s
Physical characteristics
Mass	>2.19 ± 0.20 MJ

HD 128311 b is an exoplanet orbiting in an eccentric orbit about 1 AU from its star.

[edit] HD 128311 c

HD 128311 c

Discovery
Discovered by	Vogt et al.
Discovery date	2005
Detection method	Radial velocity
Orbital characteristics
Semi-major axis	1.76 ± 0.11 AU
Eccentricity	0.170 ± 0.090
Orbital period	928 ± 18 d
Longitude of periastron	200° ± 150°
Time of periastron	2,450,010 ± 400 JD
Semi-amplitude	76.2 ± 4.6 m/s
Physical characteristics
Mass	>3.22 ± 0.49 MJ

HD 128311 c is an exoplanet orbiting in an eccentric orbit at 1.76 AU from its star.

[edit] References

• Vogt et al. (2005). "Five New Multicomponent Planetary Systems". The Astrophysical Journal 632 (1): 638 – 658. doi:10.1086/432901. 
• Butler et al. (2003). "Seven New Keck Planets Orbiting G and K Dwarfs". The Astrophysical Journal 582 (1): 455 – 466. doi:10.1086/344570. 
• Butler et al. (2006). "Catalog of Nearby Exoplanets". The Astrophysical Journal 646 (1): 505 – 522. doi:10.1086/504701.  (web Preprint)