Kepler-47b

Kepler-47b
Exoplanet List of exoplanets
Parent star
Star Kepler-47 (KOI-3154)
Constellation Cygnus
Right ascension (α) 19h 41m 11.5s
Declination (δ) +46° 55′ 12″
Apparent magnitude (mV) 15.8
Distance~4,900 ly
(1,500 pc)
Spectral type G6V / M4V
Mass (m) 1.043 / 0.36[1] M☉
Radius (r) 0.963 / 0.35[1] R☉
Temperature (T) 5636 / 3357[1] K
Metallicity [Fe/H] A: −0.25 (± 0.08)[2]
Age 4–5 Gyr
Physical characteristics
Mass(m)8.427 (± 0.62)[3] M⊕
Radius(r)3.03 (± 0.12)[2] R⊕
Stellar flux(F⊙)9.628[4] ⊕
Temperature (T) 449 K (176 °C; 349 °F)
Orbital elements
Semi-major axis(a) 0.2962 (± 0.004)[2] AU
Eccentricity (e) <0.035[2]
Orbital period(P) 49.532+0.04
−0.027[2] d
Inclination (i) 89.70+0.5
−0.16[2]°
Discovery information
Discovery date August 3, 2012[1]
Discoverer(s) Kepler spacecraft
Discovery method Transit (Kepler Mission)
Other detection methods Transit timing variations,
Transit duration variations
Discovery status Confirmed
Other designations
KOI-3154 b, KOI-3154.01, WISE J194111.49+465513.6 b, 2MASS J19411149+4655136 b, KIC 10020423 b
Database references
Extrasolar Planets
Encyclopaedia		data
SIMBADdata
Exoplanet Archivedata
Open Exoplanet Cataloguedata

Kepler-47b (also known as Kepler-47(AB)-b and by its Kepler Object of Interest designation KOI-3154.01) is an exoplanet orbiting the binary star system Kepler-47, the innermost of three such planets discovered by NASA's Kepler spacecraft. The system, also involving two other exoplanets, is located about 4,900 light-years (1,500 parsecs, or nearly 4.6×1016 km) away in the constellation Cygnus.[5] The binary system is the first to be found with more than one circumbinary planet.

Characteristics

Mass, radius and temperature

Kepler-47b is a gas giant, an exoplanet that is near the same mass and radius as the planets Jupiter and Saturn.[6] It has a temperature of 449 K (176 °C; 349 °F).[4] The planet has a radius of 3.03 R⊕, and has no solid surface.[5][7] It has a mass of 8.43 M⊕.

Host stars

The planet orbits in a circumbinary orbit around a (G-type) and (M-type) binary star system. The stars orbit each other about every 7.45 days.[2] The stars have masses of 1.04 M☉ and 0.35 M☉ and radii of 0.96 R☉ and 0.35 R☉, respectively.[2][1] They have temperatures of 5636 K and 3357 K.[2][1] Based on the stellar characteristics and orbital dynamics, an estimated age of 4–5 billion years for the system is possible. In comparison, the Sun is about 4.6 billion years old[8] and has a temperature of 5778 K.[9] The primary star is somewhat metal-poor, with a metallicity ([Fe/H]) of −0.25, or 56% of the solar amount.[1] The stars' luminosities (L☉) are 84% and 1% that of the Sun.[2][1]

The apparent magnitude of the system, or how bright it appears from Earth's perspective, is about 15.8. Therefore, it is too dim to be seen with the naked eye.

Orbit

Kepler-47b orbits around its parent stars every 45 days at a distance of 0.29 AU from its stars (close to where Mercury orbits from the Sun, which is about 0.39 AU).[10] It receives about 9.6 times as much sunlight that Earth does from the Sun.[4]

Discovery

Kepler-47b, as well as Kepler-47c, was first discovered by scientists, from both NASA and the Tel-Aviv University in Israel, using the Kepler space telescope.[5][11] Additionally, the planetary characteristics of both objects were identified by a team of astronomers at the University of Texas at Austin's McDonald observatory.[5][7] Both planets were discovered after transiting their parent stars, and they both seem to be orbiting along the same plane.[11]

Significance

Before the discovery of Kepler-47c, it was thought that binary stars with multiple planets could not exist. Gravitational issues caused by the parent stars would, it was believed, cause any circumbinary planets to either collide with each other, collide with one of the parent stars, or be flung out of orbit.[10] However, this discovery shows that multiple planets can form around binary stars, even in their habitable zones;[10] and while Kepler-47c is most likely unable to harbor life, other planets that could support life may orbit binary systems such as Kepler-47.[6]

See also

References

  1. 1 2 3 4 5 6 7 8 Orosz, Jerome A.; Welsh, William F.; Carter, Joshua A.; Fabrycky, Daniel C.; Cochran, William D.; Endl, Michael; Ford, Eric B.; Haghighipour, Nader; MacQueen, Phillip J.; Mazeh, Tsevi; Sanchis-Ojeda, Roberto; Short, Donald R.; Torres, Guillermo; Agol, Eric; Buchhave, Lars A.; Doyle, Laurance R.; Isaacson, Howard; Lissauer, Jack J.; Marcy, Geoffrey W.; Shporer, Avi; Windmiller, Gur; Barclay, Thomas; Boss, Alan P.; Clarke, Bruce D.; Fortney, Jonathan; Geary, John C.; Holman, Matthew J.; Huber, Daniel; Jenkins, Jon M.; et al. (2012). "Kepler-47: A Transiting Circumbinary Multi-Planet System". Science. 337 (6101): 1511. arXiv:1208.5489v1Freely accessible. doi:10.1126/science.1228380.
  2. 1 2 3 4 5 6 7 8 9 10 "Kepler-47 b". NASA Exoplanet Archive. Retrieved August 5, 2016.
  3. ↑ "Kepler-47". Exoplanets Data Explorer. Retrieved August 5, 2016.
  4. 1 2 3 http://www.hpcf.upr.edu/~abel/phl/hec_plots/hec_orbit/hec_orbit_Kepler-47(AB)_b.png
  5. 1 2 3 4 "Two planets ... Two stars: Nasa detects strange new solar system (and one of the planets occupies the life-supporting 'Goldilocks zone')". dailymail.co.uk. August 30, 2012. Retrieved January 5, 2013.
  6. 1 2 "Newfound 'Tatooine' Alien Planet Bodes Well for E.T. Search". space.com. September 4, 2012. Retrieved January 5, 2013.
  7. 1 2 "Astronomers Find First Multi-Planet System Around a Binary Star". spacedaily.com. September 3, 2012. Retrieved January 5, 2013.
  8. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
  9. ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
  10. 1 2 3 "Tatooine-like double-star systems can host planets". bbc.co.uk. August 29, 2012. Retrieved January 5, 2013.
  11. 1 2 "New worlds discovered, courtesy of US-Israel team". timesorisrael.com. August 30, 2012. Retrieved January 5, 2013.

Coordinates: 19h 41m 11.5s, +46° 55′ 12″

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