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HAT-P-7b / Kepler-2b
Exoplanet List of exoplanets
Exoplanet Comparison HAT-P-7 b.png
Size comparison of HAT-P-7b (gray) with Jupiter.
Parent star
Star HAT-P-7
Constellation Cygnus
Right ascension (α) 19h 28m 59s
Declination (δ) +47° 58′ 10″
Distance 1044+163
Spectral type F8
Orbital elements
Semi-major axis (a) 0.0377 ± 0.0005 AU
Eccentricity (e) 0
Orbital period (P) 2.2047299 (± 4×106) d
Inclination (i) 85.7+3.5
Inclination relative to host star's equator (i) -132.6 +10.5
Time of transit (Tt) 2453790.2593±0.001 JD
Physical characteristics
Mass (m) 1.776+0.077
Radius (r) 1.363+0.195
Density (ρ) 930 kg m−3
Surface gravity (g) 24.75 m/s² (2.524 g)
Temperature (T) 2730+150
Discovery information
Discovery date March 6, 2008
Discoverer(s) HATNet Project
Discovery method Transit
Other detection methods Radial velocity
Reflection/emission modulations
Ellipsoidal light variations
Discovery status Published
Database references
Extrasolar Planets
Exoplanet Archive data
Open Exoplanet Catalogue data

HAT-P-7b (or Kepler-2b) is an extrasolar planet discovered in 2008. It orbits very close to its host star, and is both larger and more massive than Jupiter. Due to the extreme heat it receives from its star, the dayside temperature is predicted to be 2730+150


The GSC 03547-01402 system is within the field of view of the now operational Kepler Mission spacecraft,[1] which confirmed the transit and orbital properties of the planet with significantly improved confidence and observed occultation and light curve characteristics consistent with a strongly absorbing atmosphere with limited advection to the night side. In testing itself on HAT-P-7b, Kepler proved it was sensitive enough to detect Earth-like planets.[2]

In August 2009, it was announced that HAT-P-7b may have a retrograde orbit, based upon measurements of the Rossiter–McLaughlin effect.[3][4][5] This announcement came only a day after the announcement of the first planet discovered with such an orbit, WASP-17b.

In January 2010, it was announced that HAT-P-7b was detected through ellipsoidal light variations, the first detection of such kind. This method analyses the brightness variation caused by the rotation of a star as its shape tidally distorted by the planet.[6]

On July 4, 2011, HAT-P-7b was the subject of the Hubble Space Telescope's one millionth science observation.[7]

See also[edit]


  1. ^ Pál, A.; et al. (2008). "HAT-P-7b: An Extremely Hot Massive Planet Transiting a Bright Star in the Kepler Field". The Astrophysical Journal. 680 (2): 1450–1456. arXiv:0803.0746free to read. Bibcode:2008ApJ...680.1450P. doi:10.1086/588010. 
  2. ^ W. J. Borucki, D. Koch, J. Jenkins, D. Sasselov, R. Gilliland, N. Batalha, D. W. Latham,3 D. Caldwell, G. Basri, T. Brown,7 J. Christensen-Dalsgaard, W. D. Cochran, E. DeVore, E. Dunham, A. K. Dupree, T. Gautier, J. Geary, A. Gould, S. Howell, H. Kjeldsen, J. Lissauer, G. Marcy, S. Meibom, D. Morrison, J. Tarter (2009-08-07). "Kepler's Optical Phase Curve of the Exoplanet HAT-P-7b". Science. 325 (5941): 709. Bibcode:2009Sci...325..709B. doi:10.1126/science.1178312. PMID 19661420. Retrieved 2009-08-07. 
  3. ^ Second backwards planet found, a day after the first
  4. ^ HAT-P-7: A Retrograde or Polar Orbit, and a Second Planet
  5. ^ First Evidence of a Retrograde Orbit of Transiting Exoplanet HAT-P-7b
  6. ^ Discovery of Ellipsoidal Variations in the Kepler Light Curve of HAT-P-7: William F. Welsh, Jerome A. Orosz, Sara Seager, Jonathan J. Fortney, Jon Jenkins, Jason F. Rowe, David Koch, William J. Borucki
  7. ^ NASA'S Hubble Makes One Millionth Science Observation

External links[edit]

Coordinates: Sky map 19h 28m 59s, +47° 58′ 10″