HD 189733

Starbox begin
name = HD 189733 ABStarbox image


caption = The location of the HD 189733 system.Starbox observe
epoch = J2000.0
constell = Vulpecula
ra = RA|20|00|43.7133
dec = DEC|+22|42|39.070
appmag_v = 7.66Starbox character
class = K1-K2 / M?
r-i =
v-r =
b-v =
u-b =
variable = "Suspected"Starbox astrometry
radial_v =
prop_mo_ra =
prop_mo_dec =
parallax =
p_error =
parallax = 51.94 [ .87 ]
dist_ly = 62.9
dist_pc = 19.3
space_v_u =
space_v_v =
space_v_w =
absmag_v =6.24Starbox visbin
reference =
name = HD 189733 B
period = 3,200
axis =
axis_unitless = 216 AU
eccentricity =
inclination =
node =
periastron =
periarg = Starbox detail
source =
mass = 0.8 ± 0.4
radius = 0.788 ± 0.051
gravity =
luminosity =
temperature = 4980 ± 200
metal = -0.03 ± 0.04 Fe/H
rotation =
age = >0.6 billionStarbox catalog
names = Gliese 4130, HIP 98505, V452 VulpeculaeStarbox reference
Simbad = HD+189733
ARICNS =

HD 189733, also cataloged as V452 Vulpeculae, is a binary star system approximately 63 light-years away in the constellation of Vulpecula (the Fox). The primary star is suspected to be a orange dwarf star, while the secondary star is suspected to be a red dwarf star. Given that this system has the same visual magnitude as HD 209458, it promises much for the study of close transiting extrasolar planets. The star can be found with binoculars 0.3 degrees east of the Dumbbell Nebula (M27).

As of 2005, it has been confirmed that an extrasolar planet orbits the primary star within the system. [cite journal | url=http://www.aanda.org/articles/aa/full/2005/46/aahi291/aahi291.html | author=Bouchy "et al." | title=ELODIE metallicity-biased search for transiting Hot Jupiters II. A very hot Jupiter transiting the bright K star HD 189733 | journal = Astronomy and Astrophysics | volume=444 | year=2005 | pages=L15–L19 ]

Stellar system

HD 189733 A is thought to be an orange dwarf star of the spectral type K1-2 V-VI, but the star was previously cataloged as a Solar twin, yellow dwarf star of the spectral type G5. It is thought that the star has a mass of only 82 percent that of the Sun, a radius only 0.753 percent, and a luminosity of only 26.4 percent. The star may be between 89 and 102 percent as enriched in iron as the Sun, making the star thought to be more than 600 million to at least one billion years old.

The star has starspots which affect its luminosity by 1.5 percent in visible light. [cite journal | author=Winn, J. N. "et al." | title=The Transit Light Curve Project. V. System parameters and stellar rotation period of HD 189733 | journal=Astronomical Journal| volume=133 | page= 1828-1835 |year=2007] As a result, it is in the Variable Star Catalogue as a BY Draconis variable with the variable star designation V452 Vul [peculae] .

Discovered in 2006, HD 189733 B is though to be a very dim red dwarf star of the spectral type M?V. The companion was observed at a separation of 216 astronomical units away from the primary star. Orbiting in a clockwise orbit (which is nearly perpendicular to the orbital plane of transiting planet HD 189733 b), the orbital period is estimated around 3,200 years long. [cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/503671 | author=Bakos "et al." | title=A Stellar Companion in the HD 189733 System with a Known Transiting Extrasolar Planet | journal=The Astrophysical Journal Letters | year=2006 | volume=641 | issue=1 | pages=L57–L60 | doi=10.1086/503671 ]

Planetary system

HD 189733 has one known planet, designated HD 189733 b, a gaseous giant 15% larger than Jupiter close enough to complete an orbit every two days. Using spectrometry it was found in 2007 that this planet contains significant amounts of water vapour. This planet is the second extrasolar planet where definitive evidence for water has been found. [cite web |url=http://news.bbc.co.uk/1/hi/sci/tech/6292076.stm |title=Water vapour found on exoplanet |accessdate=2007-07-12]

The chemical signature of water vapour was detected in the atmosphere of this planet. Although HD 189733b with atmospheric temperatures rising above 1 000 °C is far from being habitable, this finding increases the likelihood that water, an essential component of life, would be found on a more Earth-like planet in the future. [cite web|url=http://www.space.com/scienceastronomy/070711_water_planet.html|title='Clear Signs of Water' on Distant Planet|accessdate=2008-02-02|date=2007-07-11]

PlanetboxOrbit
exoplanet = b
mass = 1.15 ± 0.04
period = 116.6884 ± 0.0044
semimajor = 0.0313 ± 0.0004
eccentricity = 0.0010 ± 0.0002

References

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