HD 209458

Starbox begin
name=HD 209458 Starbox image


caption=The red circle shows the location of HD 209458 in Pegasus. Starbox observe
epoch=J2000
ra=22^h 03^m 10.8^s
dec=+18° 53′ 04″
appmag_v=7.65
constell=Pegasus Starbox character
class=F8-G0 V
b-v=0.59
u-b=
variable=Planetary transit Starbox astrometry
radial_v=-14.8
prop_mo_ra=28.90
prop_mo_dec=-18.37
gal_lat=-28.5269
gal_lon=76.7535
parallax=21.24
p_error=1.00
dist_ly=154
dist_pc=47.1
absmag_v=4.29 Starbox detail
mass=1.1
radius=1.2
luminosity=1.61
temperature=6000
metal=109%
rotation=14.4 days
age=2.5 × 10⁹ [ cite journal | url=http://www.journals.uchicago.edu/doi/abs/10.1086/509763 | author=Takeda "et al." | title=Structure and Evolution of Nearby Stars with Planets. II. Physical Properties of 1000 Cool Stars from the SPOCS Catalog | journal=The Astrophysical Journal Supplement Series | volume=168 | issue=2 | year=2007 | pages=297–318 | doi=10.1086/509763 [http://xxx.lanl.gov/abs/astro-ph/0607235 web preprint] ] Starbox catalog
names=BD +18°4917, SAO 107623, V376 Peg, HIP 108859. Starbox reference
Simbad=HD+209458

HD 209458 is an 8th magnitude star in the constellation Pegasus. It is very similar to our Sun, and it is classified as a yellow dwarf (spectral class G0 V). Because it is located at a distance of about 150 light years, it is not visible to the unaided eye. With good binoculars or small telescope it should be easily detectable.

In 1999 two teams working independently (one team consisted of astronomers at the Geneva Observatory, the Harvard-Smithsonian Center for Astrophysics, and the Wise Observatory; the second group was the California and Carnegie Planet Search team) discovered an extrasolar planet orbiting the star by using the radial velocity planet search method. Soon after the discovery, separate teams led by David Charbonneau and Gregory W. Henry were able to detect a transit of the planet across the surface of the star making it the first known transiting extrasolar planet. [ cite journal | url=http://www.journals.uchicago.edu/doi/full/10.1086/312457 | author=Charbonneau "et al." | title=Detection of Planetary Transits Across a Sun-like Star | journal=The Astrophysical Journal Letters | volume=529 | issue=1 | year=2000 | pages=L45–L48 | doi=10.1086/312457 ] The planet received the designation "HD 209458 b".

Because the planet transits the star, the star is dimmed by about 2% every 3.5 days making it an extrinsic variable. The variable star designation for HD 209458 is V376 Pegasi. It is the prototype of the V376 Pegasi variables, all of which show transits by a planet. [http://www.sai.msu.su/groups/cluster/gcvs/gcvs/iii/vartype.txt]

Planetary system

HD 209458 b is an extrasolar planet that orbits the Sun-like star HD 209458 in the constellation Pegasus. Spectroscopic studies first revealed the presence of a planet around HD 209458 on November 5, 1999. The planet is now under even more public scrutiny with the announcement that its atmosphere contains water vapor. Astronomers had made careful photometric measurements of several stars known to be orbited by planets, in the hope that they might observe a dip in brightness caused by the transit of the planet across the star's face. This would require the planet's orbit to be inclined such that it would pass between the Earth and the star, and previously no transits had been detected.

Travis Barman at Lowell Observatory in Flagstaff, Arizona analyzed the emission spectrum of this planet, and believes that its atmosphere contains water [cite journal | url = http://www.journals.uchicago.edu/doi/abs/10.1086/518736 | author = Barman | title = Identification of Absorption Features in an Extrasolar Planet Atmosphere | journal = The Astrophysical Journal Letters | volume=661 | issue=2 | year=2007 | pages=L191–L194 ( [http://fr.arxiv.org/abs/0704.1114 web Preprint] )] , although previous research [cite journal | author=L. J. Richardson "et al." | journal=Nature | title= A spectrum of an extrasolar planet| volume=445 |pages= 892–895 |year= 2007 | url=http://www.nature.com/nature/journal/v445/n7130/full/nature05636.html] suggests that the atmosphere is composed mostly of silicate clouds.

PlanetboxOrbit
exoplanet = b
mass = 0.69 ± 0.05
period = 3.52474541 ± 0.00000025
semimajor = 0.045
eccentricity = 0.00

References

* Tsevi Mazeh "et al", 2000, "The Spectroscopic Orbit of the Planetary Companion Transiting HD 209458", "Astrophysical Journal", vol. 532, pp. L55–L58.

External links

* [http://simbad.u-strasbg.fr/Simbad SIMBAD] [http://simbad.u-strasbg.fr/sim-id.pl?protocol=html&Ident=HD+209458 entry]