Astronomy:Kepler-56b

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Short description: Hot Neptune orbiting Kepler-56
Kepler-56b
Kepler-56 System Diagram.jpg
A diagram of the planetary system of Kepler-56
Discovery
Discovered byDaniel Huber et al.[1]
Discovery date16 October 2013
Transit method
Orbital characteristics
0.1028 ± 0.0037 AU (15,380,000 ± 550,000 km)[1]
Orbital period10.5016+0.0011
−0.0010
[1] d
StarKepler-56
Physical characteristics
Mean radius6.51+0.29
−0.28
[1] R
Mass22.1+3.9
−3.6
[1] M
Mean density0.442+0.080
−0.072
g cm−3


Kepler-56b (KOI-1241.02)[2] is a hot Neptune[1]—a class of exoplanets—located roughly 3,060 light-years (940 parsecs) away. It is somewhat larger than Neptune[3] and orbits its parent star Kepler-56 and was discovered in 2013 by the Kepler Space Telescope.

Planetary orbit

Kepler-56b is about 0.1028 astronomical unit|AU (9.56 million mi; 15.38 million km) away from its host star[1] (about one-tenth of the distance between Earth to the Sun), making it even closer to its parent star than Mercury (0.39 AU [36 million mi; 58 million km]) and Venus (0.72 AU [67 million mi; 110 million km]). It takes 10.5 days for Kepler-56b to complete a full orbit around its star.[1] Further research shows that Kepler-56b's orbit is about 45° misaligned to the host star's equator. Later radial velocity measurements have revealed evidence of a gravitational perturbation from Kepler-56d.

Both Kepler-56b and Kepler-56c will be devoured by their parent star in about 130 and 155 million years.[4] Even further research shows that it will have its atmosphere boiled away by intense heat from the star, and it will be stretched by the strengthening stellar tides.[4] The measured mass of Kepler-56b is about 30% larger than Neptune's mass, but its radius is roughly 70% larger than Neptune's. Therefore, Kepler-56b should have a hydrogen/helium envelope containing a significant fraction of its total mass.[5][6] Like Kepler-11b and Kepler-11c, the envelope's light elements are susceptible to photo-evaporation caused by radiation from the central star. For example, it has been calculated that Kepler-11c lost over 50% of its hydrogen/helium envelope after formation.[7] However, the larger mass of Kepler-56b, compared to that of Kepler-11c, reduces the efficiency of mass loss.[7] Nonetheless, the planet may have been significantly more massive in the past and may keep losing mass in the future.

Other planets in the Kepler-56 system

References

  1. 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 Huber, D. et al. (2013). "Stellar Spin-Orbit Misalignment in a Multiplanet System". Science 342 (6156): 331–334. doi:10.1126/science.1242066. PMID 24136961. Bibcode2013Sci...342..331H. 
  2. "KOI-1241.02". SIMBAD. Centre de données astronomiques de Strasbourg. http://simbad.u-strasbg.fr/simbad/sim-basic?Ident=KOI-1241.02. 
  3. "NASA Exoplanet Archive". Operated by the California Institute of Technology, under contract with NASA. https://exoplanetarchive.ipac.caltech.edu/index.html. 
  4. 4.0 4.1 Charles Poladian (2014-06-03). "Cosmic Snack: Planets Kepler-56b And Kepler-56c Will Be Swallowed Whole By Host Star". International Business Times. http://www.ibtimes.com/cosmic-snack-planets-kepler-56b-kepler-56c-will-be-swallowed-whole-host-star-1593918. Retrieved 2017-09-07. 
  5. Lissauer, J. J.; Hubickyj, O.; D'Angelo, G.; Bodenheimer, P. (2009). "Models of Jupiter's growth incorporating thermal and hydrodynamic constraints". Icarus 199 (2): 338–350. doi:10.1016/j.icarus.2008.10.004. Bibcode2009Icar..199..338L. 
  6. D'Angelo, G.; Weidenschilling, S. J.; Lissauer, J. J.; Bodenheimer, P. (2014). "Growth of Jupiter: Enhancement of core accretion by a voluminous low-mass envelope". Icarus 241: 298–312. doi:10.1016/j.icarus.2014.06.029. Bibcode2014Icar..241..298D. 
  7. 7.0 7.1 D'Angelo, G.; Bodenheimer, P. (2016). "In Situ and Ex Situ Formation Models of Kepler 11 Planets". The Astrophysical Journal 828 (1): id. 33. doi:10.3847/0004-637X/828/1/33. Bibcode2016ApJ...828...33D. 

Further reading

  • Steffen, Jason H et al. (20 August 2012). "Transit Timing Observations from Kepler: VII. Confirmation of 27 planets in 13 multiplanet systems via Transit Timing Variations and orbital stability". Mon. Not. R. Astron. Soc. 428 (2): 1077. doi:10.1093/mnras/sts090. Bibcode2013MNRAS.428.1077S. 

External links