Kepler-33 is a star in the constellation of
Cygnus with a system of five known planets. Having just begun to evolve off from the
main sequence,
[ its radius and mass are difficult to ascertain, although data available in 2020 shows its best-fit mass of 1.3 and diameter of 1.6 are compatible with a model of a ]subgiant
A subgiant is a star that is brighter than a normal main-sequence star of the same spectral class, but not as bright as giant stars. The term subgiant is applied both to a particular spectral luminosity class and to a stage in the evolution ...
star.
Planetary system
First detections of the four-body planetary system were reported in February 2011. On January 26, 2012, a 5th planet around the star was confirmed.[ However, unlike other planets confirmed via Kepler, their masses were initially not known, as Doppler Spectroscopy measurements were not done before the announcement. Judging by their radii, b may be a large ]Super-Earth
A super-Earth is an extrasolar planet with a mass higher than Earth's, but substantially below those of the Solar System's ice giants, Uranus and Neptune, which are 14.5 and 17 times Earth's, respectively.
The term "super-Earth" refers only to ...
or small Hot Neptune
A hot Neptune or Hoptune is a type of giant planet with a mass similar to that of Uranus or Neptune orbiting close to its star, normally within less than 1 AU. The first hot Neptune to be discovered with certainty was Gliese 436 b in 2007, an exo ...
while the other four are all likely to be the latter.
Planets b and c may actually be in a 7:3 resonance, as there is a 0.05 day discrepancy; there is also a small 0.18 day discrepancy between a 5:3 resonance between planets c and d. The other planets do not seem to be in any resonances, though near resonances are 3d:2e and 4e:3f.
The planetary system in current configuration is highly susceptible to perturbations, therefore assuming stability, no additional giant planets can be located within 30 AU from the parent star.
See also
* 55 Cancri
55 Cancri is a binary star system located 41 light-years away from the Sun in the zodiac constellation of Cancer. It has the Bayer designation Rho1 Cancri (ρ1 Cancri); ''55 Cancri'' is the Flamsteed designation (abbr ...
* Kepler-11
* Kepler-20
Kepler-20 is a star 929 light-years from Earth in the constellation Lyra with a system of six known planets. The apparent magnitude of this star is 12.51, so it cannot be seen with the unaided eye. Viewing it requires a telescope with an a ...
References
Cygnus (constellation)
G-type subgiants
707
Planetary transit variables
Planetary systems with five confirmed planets
J19161861+4600187
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