HAT-P-2b

Planetbox begin
name = HAT-P-2 b| Planetbox star
star = HD 147506
constell = Hercules
RA = RA|16|20|36
DEC = DEC|+41|02|53
dist_ly = 440 ± 52
dist_pc = 135 ± 16
class = F8V Planetbox orbit
period = 5.63341±0.00013 dayscite journal |authors=B. Loeillet, A. Shporer, F. Bouchy, F. Pont, T. Mazeh, J. L. Beuzit, I. Boisse, X. Bonfils, R. Da Silva, X. Delfosse, M. Desort, A. Ecuvillon, T. Forveille, F. Galland, A. Gallenne, G. Hébrard, A.-M. Lagrange, C. Lovis, M. Mayor, C. Moutou, F. Pepe, C. Perrier, D. Queloz, D. Ségransan, J. P. Sivan, N. C. Santos, Y. Tsodikovich, S. Udry, and A. Vidal-Madjar |year=2008 |title=Refined parameters and spectroscopic transit of the super-massive planet HD 147506b |url=http://www.aanda.org/index.php?option=article&access=standard&Itemid=129&url=/articles/aa/abs/2008/14/aa8167-07/aa8167-07.html journal=Astronomy & Astrophysics |volume=481 |pages=529-533 |accessdate=2008-03-27]
eccentricity = 0.5163^+0.0025_-0.0023
semimajor = 0.0677^+0.0011_-0.0017
inclination = 90^+0.85_-0.93
ang_dist = 0.501
long_peri = 189.92^1.06_-1.2
t_peri = 2,454,213.4794^+0.0053_-0.003
semi-amp = 885±37Planetbox character
mass = 8.65^+0.39_-0.55
density = 12500^+2.6_-3.6
gravity = 235.5
gravity_earth = 24.01
temperature = 1187cite news| url=http://news.nationalgeographic.com/news/2007/05/070503-new-planet.html| title="Weird" New Planet Weighs as Much as 2,500 Earths| first=Kate| last= Ravilious| publisher= National Geographic News| date=May 3, 2007| accessdate=2007-05-04]
radius = 0.951^+0.009_-0.053 Planetbox discovery
discovery_date = 2007-05-02
discoverers = HATNet Project
discovery_method = Transit
discovery_status = Published

HAT-P-2 b is an extrasolar planet detected by the HATNet Project in May 2007. It orbits a class F star, (bigger and hotter than the Sun), located about 440 light-years away in the constellation Hercules. Every 5 days 15 hours, it crosses directly in front of the star as viewed from Earth.cite press release| url=http://www.cfa.harvard.edu/press/2007/pr200711.html| title=Astronomers find super-massive planet| publisher=Harvard-Smithsonian Center for Astrophysics| date= May 2, 2007]

Orbit and mass

The planet's mass has been estimated to be 8.65 times that of Jupiter, while its radius is 0.951 times that of Jupiter which is not uncommon for a superjovian. Its small size despite the bloating of planet's atmosphere is caused by the strong gravitational pull of the massive planet pulling towards the center. This indicates that the planet's mean density is two times that of Earth and its surface gravity is approximately 24 times that on Earth, almost equal to the Sun. The orbit is very eccentric, ranging from 4.90 million miles to 15.36 million miles from the star; if Earth's orbit were as eccentric its distance from the sun would vary from a distance of 0.4837 AU to a distance equivalent to Mars (1.5163 AU).

In addition to heat from its primary star, tidal heating is thought to have played a significant role in this planet's evolution. [cite journal|title=Tidal Heating of Extra-Solar Planets| first= Brian| last= Jackson| coauthors= Richard Greenberg, Rory Barnes| journal=ApJ| id=arXiv|0803.0026 | year=2008 ]

Rotation

As of August 2008, the most recent calculation of HAT-P-2b's Rossiter-McLaughlin effect and so spin-orbit angle was that of Winn in 2007 but Loeillet has in 2008 disputed it. [cite arXiv | title= Measuring accurate transit parameters | author=Joshua N. Winn | eprint=0807.4929v2 |class=astro-ph |year=2008 cite journal| title= | author=Loeillet "et al." |journal=A&A| volume=481| page=529|year=2008] For Winn this is +1 ± 13 degrees. [cite journal| title= | author=Winn "et al." |journal=Astrophysical Journal (Letters)| volume=665| page=L167 |year=2007]

It has been suggested that there is a second outer planet perturbing HAT-P-2 b. This has not so far been proved or disproved.

References

External links

* [http://www.exoplanet.eu/ The Extrasolar Planets Encyclopaedia]
* [http://tauac.typepad.com/ac/2007/05/tauled_team_hel.html The Israeli Team From Tel Aviv University]