Kepler-47b

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Kepler-47b
Orbiting in the Habitable Zone of Two Suns.jpg
This diagram compares our own solar system to Kepler-47, a double-star system containing two planets, one orbiting in the so-called "habitable zone."
Discovery
Discovered by Kepler spacecraft
Discovery dateAugust 3, 2012 [1]
Transit (Kepler Mission)
Orbital characteristics
0.2962 (± 0.004) [2] AU
Eccentricity <0.035 [2]
49.532+0.04
−0.027 [2] d
Inclination 89.70+0.5
−0.16 [2]
Star Kepler-47 (KOI-3154)
Physical characteristics
Mean radius
3.03 (± 0.12) [2] REarth
Mass 8.427 (± 0.62) [3] MEarth
Temperature 449 K (176 °C; 349 °F)

    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 3,400 light-years (1,060 parsecs) away.

    Contents

    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. [4] It has a temperature of 449 K (176 °C; 349 °F). [5] The planet has a radius of 3.03 REarth, and has no solid surface. [6] It has a mass of 8.43 MEarth.

    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 [7] and has a temperature of 5778 K. [8] 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). [9] It receives about 9.6 times as much sunlight that Earth does from the Sun. [5]

    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. [10] Additionally, the planetary characteristics of both objects were identified by a team of astronomers at the University of Texas at Austin's McDonald observatory. [6] Both planets were discovered after transiting their parent stars, and they both seem to be orbiting along the same plane. [10]

    Significance

    Prior to 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. [9] However, this discovery shows that multiple planets can form around binary stars, even in their habitable zones; [9] 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. [4]

    See also

    Related Research Articles

    Kepler space telescope Tenth mission of the Discovery program; optical space telescope for exoplanetology

    The Kepler space telescope is a retired space telescope launched by NASA in 2009 to discover Earth-size planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018.

    Circumbinary planet Planet that orbits two stars instead of one

    A circumbinary planet is a planet that orbits two stars instead of one. The two stars orbit each other in a binary star system, while the planet typically orbits farther from the center of the system than either of the two stars, although planets in stable orbits around one of the two stars in a binary are known. Studies in 2013 showed that there is a strong hint that the planet and stars originate from a single disk.

    Kepler-10 Sunlike star in the constellation Draco

    Kepler-10, formerly known as KOI-72, is a Sun-like star in the constellation of Draco that lies 187 parsecs from Earth. Kepler-10 was targeted by NASA's Kepler spacecraft, as it was seen as the first star identified by the Kepler mission that could be a possible host to a small, transiting exoplanet. The star is slightly less massive, slightly larger, and slightly cooler than the Sun; at an estimated 10.4 billion years in age, Kepler-10 is almost 2.6 times the age of the Sun. Kepler-10 is host to a planetary system made up of at least two planets. Kepler-10b, the first undeniably rocky planet, was discovered in its orbit after eight months of observation and announced on January 10, 2011. The planet orbits its star closely, completing an orbit every 0.8 days, and has a density similar to that of iron. The second planet, Kepler-10c, was confirmed on May 23, 2011, based on follow-up observations by the Spitzer Space Telescope. The data shows it has an orbital period of 42.3 days and has a radius more than double that of Earth, but a higher density, making it the largest and most massive rocky planet discovered as of June 2014.

    Kepler-16b Gas giant orbiting Kepler-16 star system

    Kepler-16b is an extrasolar planet. It is a Saturn-mass planet consisting of half gas and half rock and ice, and it orbits a binary star, Kepler-16, with a period of 229 days. "[It] is the first confirmed, unambiguous example of a circumbinary planet – a planet orbiting not one, but two stars," said Josh Carter of the Harvard-Smithsonian Center for Astrophysics, one of the discovery team.

    Kepler-35 is a binary star system in the constellation of Cygnus. These stars, called Kepler-35A and Kepler-35B have masses of 89% and 81% solar masses respectively, and both are assumed to be of spectral class G. They are separated by 0.176 AU, and complete an eccentric orbit around a common center of mass every 20.73 days.

    Kepler-47 is a binary star system of constellation Cygnus with three exoplanets in orbit around the pair of stars located about 1055 parsecs away from Earth. The first two planets announced are designated Kepler-47b, and Kepler-47c. Kepler-47 is the first circumbinary multi-planet system discovered by the Kepler mission. The outermost of the planets is a gas giant orbiting within the habitable zone of the stars. Because most stars are binary, the discovery that multi-planet systems can form in such a system has impacted previous theories of planetary formation.

    Kepler-47c Goldilocks gas giant orbiting Kepler-47 system

    Kepler-47c is an exoplanet orbiting the binary star system Kepler-47, the outermost of three such planets discovered by NASA's Kepler spacecraft. The system, also involving two other exoplanets, is located about 3,400 light-years away.

    Kepler-62 K-type star in the constellation Lyra

    Kepler-62 is a K-type main sequence star cooler and smaller than the Sun, located roughly 990 light years from Earth in the constellation Lyra. It resides within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets that may be transiting their stars. On April 18, 2013, it was announced that the star has five planets, two of which, Kepler-62e and Kepler-62f are within the star's habitable zone. The outermost, Kepler-62f, is likely a rocky planet.

    Kepler-62e Habitable-zone super-Earth planet orbiting Kepler-62

    Kepler-62e is a super-Earth exoplanet discovered orbiting within the habitable zone of Kepler-62, the second outermost of five such planets discovered by NASA's Kepler spacecraft. Kepler-62e is located about 1,200 light-years from Earth in the constellation of Lyra. The exoplanet was found using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Kepler-62e may be a terrestrial or ocean-covered planet; it lies in the inner part of its host star's habitable zone.

    Kepler-62c is an approximately Mars-sized exoplanet discovered in orbit around the star Kepler-62, the second innermost of five discovered by NASA's Kepler spacecraft around Kepler-62. At the time of discovery it was the second-smallest exoplanet discovered and confirmed by the Kepler spacecraft, after Kepler-37b. It was found using the transit method, in which the dimming that a planet causes as it crosses in front of its star is measured. Its stellar flux is 25 ± 3 times Earth's. It is similar to Mercury.

    Kepler-61b is a super-Earth exoplanet orbiting within parts of the habitable zone of the K-type main-sequence star Kepler-61. It is located about 1,100 light-years from Earth in the constellation of Cygnus. It was discovered in 2013 using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured, by NASA's Kepler spacecraft.

    Habitability of binary star systems Potential conditions for extraterrestrial life in binary star systems

    Planets in binary star systems may be candidates for supporting extraterrestrial life. Habitability of binary star systems is determined by many factors from a variety of sources. Typical estimates often suggest that 50% or more of all star systems are binary systems. This may be partly due to sample bias, as massive and bright stars tend to be in binaries and these are most easily observed and catalogued; a more precise analysis has suggested that the more common fainter stars are usually singular, and that up to two thirds of all stellar systems are therefore solitary.

    Kepler-442b Super-Earth orbiting Kepler-442

    Kepler-442b is a confirmed near-Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the K-type main-sequence star Kepler-442, about 1,206 light-years (370 pc) from Earth in the constellation of Lyra.

    Kepler-452b Super-Earth exoplanet orbiting Kepler-452

    Kepler-452b is a super-Earth exoplanet orbiting within the inner edge of the habitable zone of the sunlike star Kepler-452 and is the only planet in the system discovered by Kepler. It is located about 1,800 light-years (550 pc) from Earth in the constellation of Cygnus.

    Kepler-419c is a super-Jupiter exoplanet orbiting within the habitable zone of the star Kepler-419, the outermost of two such planets discovered by NASA's Kepler spacecraft. It is located about 3,400 light-years from Earth in the constellation Cygnus. The exoplanet was found by using the transit timing variation method, in which the variations of transit data from an exoplanet are studied to reveal a more distant companion.

    Kepler-1647b Circumbinary gas giant orbiting the Kepler-1647 star system

    Kepler-1647b is a circumbinary exoplanet that orbits the binary star system Kepler-1647, 3,700 light-years (1,100 pc) from Earth in the constellation Cygnus. It was announced on June 13, 2016, in San Diego at a meeting of the American Astronomical Society. It was detected using the transit method, when it caused the dimming of the primary star, and then again of the secondary star blended with the primary star eclipse. The first transit of the planet was identified in 2012, but at the time the single event was not enough to rule out contamination, or confirm it as a planet. It was discovered by the analysis of the Kepler light-curve, which showed the planet in transit.

    Kepler-1229 is a red dwarf star located about 870 light-years (270 pc) away from the Earth in the constellation of Cygnus. It is known to host a super-Earth exoplanet within its habitable zone, Kepler-1229b, which was discovered in 2016.

    Kepler-419b is a hot Jupiter exoplanet orbiting the star Kepler-419, the outermost of two such planets discovered by NASA's Kepler spacecraft. It is located about 3,400 light-years (1040 parsecs from Earth in the constellation Cygnus.

    OGLE-2007-BLG-349(AB)b Super Neptune orbiting the OGLE-2007-BLG-349 system

    OGLE-2007-BLG-349(AB)b is a circumbinary extrasolar planet about 8,000 light-years away in the constellation of Sagittarius. It is the first circumbinary exoplanet to be discovered using the microlensing method of detecting exoplanets.

    Planet-hosting stars are stars which host planets, therefore forming planetary systems.

    References

    1. 1 2 3 4 5 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): 1511–4. arXiv: 1208.5489v1 . Bibcode:2012Sci...337.1511O. doi:10.1126/science.1228380. PMID   22933522. S2CID   44970411.
    2. 1 2 3 4 5 6 7 8 9 "Kepler-47 b". NASA Exoplanet Archive. Retrieved August 5, 2016.
    3. ↑ "Kepler-47". Exoplanets Data Explorer. Retrieved August 5, 2016.
    4. 1 2 "Newfound 'Tatooine' Alien Planet Bodes Well for E.T. Search". space.com. September 4, 2012. Retrieved January 5, 2013.
    5. 1 2 http://www.hpcf.upr.edu/~abel/phl/hec_plots/hec_orbit/hec_orbit_Kepler-47(AB)_b.png [ bare URL image file ]
    6. 1 2 "Astronomers Find First Multi-Planet System Around a Binary Star". spacedaily.com. September 3, 2012. Retrieved January 5, 2013.
    7. ↑ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 19 February 2011.
    8. ↑ Fraser Cain (September 15, 2008). "Temperature of the Sun". Universe Today. Retrieved 19 February 2011.
    9. 1 2 3 "Tatooine-like double-star systems can host planets". bbc.co.uk. August 29, 2012. Retrieved January 5, 2013.
    10. 1 2 "New worlds discovered, courtesy of US-Israel team". timesorisrael.com. August 30, 2012. Retrieved January 5, 2013.

    Coordinates: Jupiter and moon.png 19h 41m 11.5s, +46° 55′ 12″

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