HD 74156

Starbox begin
name = HD 74156Starbox observe
epoch = J2000.0
constell = Hydra
ra = RA|08|42|25.1222
dec = DEC|+04|34|41.151
appmag_v = +7.62 Starbox character
class = G0V
r-i = 0.2
v-r = 0.4
b-v = 0.580
u-b = ?
variable = “None” Starbox astrometry
radial_v = +3.7
prop_mo_ra = 24.96
prop_mo_dec = –200.48
parallax = 15.49
p_error = 1.10
dist_ly = 210.6
dist_pc = 64.56
absmag_v = +3.57 Starbox detail
age = 7.38
metal = +0.13
mass = 1.24±0.04
radius = 1.58
gravity = 4.20
rotation = 4.02 km/s
luminosity = 2.96
temperature = 6039 Starbox catalog
names = HIP 42723, GC 11970, SAO 117040 Starbox reference
Simbad = HD+74156
ARICNS =

HD 74156 is a yellow dwarf star (spectral type G0V) in the constellation of Hydra, 211 light years from our solar system. It is known to be orbited by three large planets.

Star

This star is 24% more massive and 58% larger than our Sun. The total luminosity of the star is 2.96 times that of our Sun and with temperature 6039 K. The age of the star is older at 7.38 gigayears with metallicity 1.35 times the Sun based on its abundance of iron.

Planetary system

In April 2001, two giant planets were announced orbiting the star. [cite journal | url=http://www.aanda.org/articles/aa/full/2004/04/aa0091/aa0091.html | author=Naef "et al." | title=The ELODIE survey for northern extra-solar planets III. Three planetary candidates detected with ELODIE | journal=Astronomy and Astrophysics | year=2004 | volume=414 | issue=1 | pages=351–359 | doi=10.1051/0004-6361:20034091 ] The first planet HD 74156 b orbit the star closer to Mercury in extremely eccentric orbit. The second planet HD 74156 c is a long-period, massive planet (massing 8 Jupiters), which orbits 74% the distance between Sun and Jupiter. However, it left a stable gap between two planets, in which astronomers predicted the existence of at least one additional planet orbiting in this zone. Part of this zone includes the stellar habitable zone at 1.72 AU from the star. [Square root of stellar luminosity 2.96, as per habitable zone article.]

In September 2007, a third planet HD 74156 d was proposed orbiting between planets b and c, which placed it in the stable gap prior predicted. This planet would orbit at similar distance to the star as from Earth to the Sun (too hot, it turns out, for this system's habitable zone), but with eccentric orbit and larger than Saturn. However Roman V. Baluev has cast doubt on this discovery due to errors in the data. [cite arXiv | title=Accounting for velocity jitters in planet search surveys |author=Roman V. Baluev |class=astro-ph |eprint=0712.3862v2 |year=2008] The initial discoverers have not yet addressed Baluev's concern. [cite arXiv | title=The Successful Prediction of the Extrasolar Planet HD 74156 d | author=Rory Barnes, Krzysztof Gozdziewski, Sean N. Raymond |class=astro-ph |eprint=0804.4496v1 |year=2008]

PlanetboxOrbit
exoplanet = b
mass = >1.88 ± 0.03
period = 51.65 ± 0.01
semimajor = 0.294
eccentricity = 0.64 ± 0.01PlanetboxOrbit
exoplanet = "d"
mass = >0.396 ± 0.02
period = 336.6 ± 3.6
semimajor = 1.01
eccentricity = 0.25 ± 0.11PlanetboxOrbit
exoplanet = c
mass = >8.03 ± 0.12
period = 2476 ± 8.7
semimajor = 3.85
eccentricity = 0.43 ± 0.01

References

See also

* List of stars with confirmed extrasolar planets
* HD 37124
* Upsilon Andromedae

External links

*
*
* [http://www.lpl.arizona.edu/~rory/research/xsp/dynamics/ Extrasolar Planet Interactions] by Rory Barnes & Richard Greenberg, Lunar and Planetary Lab, University of Arizona