HAT-P-2b
{{short description|Extrasolar planet}}
{{Infobox planet
| name = HAT-P-2b / Magor
| image = Exoplanet Comparison HAT-P-2 b.png
| caption = Size comparison of HAT-P-2b with Jupiter.
| discoverer = HATNet Project
| discovery_method = Transit
| alt_names = HD 147506 b, Magor
| apsis = astron
| semimajor = {{val|0.06880|0.00065|0.00070|ul=AU}}
| eccentricity = {{val|0.50833|0.00082|0.00075}}
| period = {{val|5.6334754|0.0000026|ul=d}}
| inclination = {{val|86.72|1.1|0.87|u=deg}}
| time_periastron = {{val|2455289.4721|0.0038}}
| arg_peri = {{val|186.96|0.87|0.88|u=deg}}
| semi-amplitude = {{val|938.1|10.0|9.9|ul=m/s}}
| star = HD 147506
| mean_radius = {{val|1.157|0.073|0.063|ul=Jupiter radius}}
| mass = {{val|8.70|0.19|0.20|ul=Jupiter mass}}
| density = {{val|7.3|1.4|1.1|ul=g/cm3}}
| surface_grav = {{val|162|27}} m/s²
| single_temperature = {{val|1540|30|ul=K}}
}}
HAT-P-2b is an extrasolar planet detected by the HATNet Project in May 2007. It orbits a class F star HAT-P-2, (bigger and hotter than the Sun), located about 420 light-years away in the constellation Hercules.
The planet is officially named Magor. The name was selected in the NameExoWorlds campaign by Hungary, during the 100th anniversary of the International Astronomical Union. Magor was a legendary ancestor of the Magyar people and the Hungarian nation, and brother of Hunor (name of the star HAT-P-2).{{Cite web|url=http://www.nameexoworlds.iau.org/final-results|title=Approved names|website=NameExoworlds|language=en|access-date=2020-01-02}}{{Cite web|url=https://www.iau.org/news/pressreleases/detail/iau1912/|title=International Astronomical Union {{!}} IAU|website=www.iau.org|access-date=2020-01-02}}
Physical properties
The planet's mass has been estimated to be 8.7 times that of Jupiter, while its diameter is 1.157 times Jupiter's. Its small size, despite the bloating of the planet's atmosphere, is caused by the strong gravity of the planet. The planetary atmosphere has indeed the smallest scale height, equal to 26km, among exoplanets with measurable atmospheres as of 2021.{{citation|arxiv=2103.07185|year=2021|title=Evidence for disequilibrium chemistry from vertical mixing in hot Jupiter atmospheres|doi=10.1051/0004-6361/202039708|last1=Baxter|first1=Claire|last2=Désert|first2=Jean-Michel|last3=Tsai|first3=Shang-Min|last4=Todorov|first4=Kamen O.|last5=Bean|first5=Jacob L.|last6=Deming|first6=Drake|last7=Parmentier|first7=Vivien|last8=Fortney|first8=Jonathan J.|last9=Line|first9=Michael|last10=Thorngren|first10=Daniel|last11=Pierrehumbert|first11=Raymond T.|last12=Burrows|first12=Adam|last13=Showman|first13=Adam P.|journal=Astronomy & Astrophysics|volume=648|pages=A127|s2cid=232222174 }}
This indicates its mean density is twice that of Earth and its surface gravity approximately 24 times that of Earth, almost equal to the Sun.
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| display-authors= 1| last= Jackson|author2=Richard Greenberg |author3=Rory Barnes | journal=Astrophysical Journal| date=2008| arxiv=0803.0026|bibcode = 2008ApJ...681.1631J |doi = 10.1086/587641|volume=681|issue=2|pages=1631 | s2cid= 42315630}}
Orbit
The planetary orbital period is 5 days 15 hours, and its inclination is such that it crosses directly in front of the star as viewed from Earth. The orbit is very eccentric, ranging from 4.90 million to 15.36 million miles from the star.
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 journal | title= Measuring accurate transit parameters | author=Joshua N. Winn |date=2008 | doi= 10.1017/S174392130802629X | journal= Proceedings of the International Astronomical Union | volume= 4 | pages= 99–109 | arxiv=0807.4929 | bibcode= 2009IAUS..253...99W| s2cid=34144676 }} For Winn, this is +1 ± 13 degrees.{{cite journal| title=Spin-Orbit Alignment for the Eccentric Exoplanet HD 147506b | display-authors=etal | author=Winn | journal=Astrophysical Journal Letters | volume=665 | issue=2 | page=L167 | date=2007 | doi=10.1086/521362 | bibcode=2007ApJ...665L.167W |arxiv = 0707.0503 | s2cid=330965 }} The study in 2012 determined the planetary orbit is probably aligned with the equatorial plane of the star, with misalignment equal to 9{{±|10}}°.{{citation|arxiv=1206.6105|title=Obliquities of Hot Jupiter Host Stars: Evidence for Tidal Interactions and Primordial Misalignments|year=2012|doi=10.1088/0004-637X/757/1/18|last1=Albrecht|first1=Simon|last2=Winn|first2=Joshua N.|last3=Johnson|first3=John A.|last4=Howard|first4=Andrew W.|last5=Marcy|first5=Geoffrey W.|last6=Butler|first6=R. Paul|last7=Arriagada|first7=Pamela|last8=Crane|first8=Jeffrey D.|last9=Shectman|first9=Stephen A.|last10=Thompson|first10=Ian B.|last11=Hirano|first11=Teruyuki|last12=Bakos|first12=Gaspar|last13=Hartman|first13=Joel D.|journal=The Astrophysical Journal|volume=757|issue=1 |page=18|bibcode=2012ApJ...757...18A |s2cid=17174530 }}
Other planets in the system
References
{{Reflist|refs=
{{cite press release | title=Astronomers find super-massive planet | url=http://www.cfa.harvard.edu/press/2007/pr200711.html | last1=Aguilar | first1=David A. | last2=Pulliam | first2=Christine | publisher=Harvard-Smithsonian Center for Astrophysics | date=2007-05-01 | access-date=2019-01-05}}
}}
External links
{{commonscat-inline|HAT-P-2 b|HAT-P-2b}}
- [https://exoplanet.eu/home/ The Extrasolar Planets Encyclopaedia]
- [https://web.archive.org/web/20070927212511/http://tauac.typepad.com/ac/2007/05/tauled_team_hel.html The Israeli Team From Tel Aviv University]
{{Sky|16|20|36|+|41|02|53|440}}
{{DEFAULTSORT:Hat-P-2b}}
Category:Hercules (constellation)
Category:Transiting exoplanets
Category:Exoplanets discovered in 2007