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Kepler-7

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Kepler-7
Kepler-7-Sun comparison.png
Kepler-7-Sun comparison
Observation data
Epoch J2000      Equinox J2000
Constellation Lyra
Right ascension  19h 14m 19.5623s[1]
Declination +41° 05′ 23.365″[1]
Apparent magnitude (V) 13.005±0.039[2]
Characteristics
Spectral type G0[3]
Apparent magnitude (J) 11.833±0.020[4]
Apparent magnitude (H) 11.601±0.022[4]
Apparent magnitude (K) 11.535±0.020[4]
Apparent magnitude (B) 13.620±0.029[2]
Astrometry
Radial velocity (Rv)+0.40 ± 0.10[5] km/s
Proper motion (μ) RA: −2.956±0.050[1] mas/yr
Dec.: −20.949±0.042[1] mas/yr
Parallax (π)1.0554 ± 0.0235[1] mas
Distance3,090 ± 70 ly
(950 ± 20 pc)
Details[5]
Mass1.347+0.072
−0.054
 M
Radius1.843+0.048
−0.066
 R
Luminosity4.15+0.63
−0.54
 L
Surface gravity (log g)3.98 ± 0.10 cgs
Temperature5933 ± 44 K
Metallicity [Fe/H]+0.11 ± 0.03 dex
Rotational velocity (v sin i)4.2 ± 0.5 km/s
Age3.3 ± 0.4 Gyr
Other designations
WDS J19143+4105AB, KOI-97, KIC 5780885, 2MASS J19141956+4105233[3]
Database references
SIMBADdata

Kepler-7 is a star located in the constellation Lyra in the field of view of the Kepler Mission, a NASA operation in search of Earth-like planets. It is home to the fourth of the first five planets that Kepler discovered; this planet, a Jupiter-size gas giant named Kepler-7b, is as light as styrofoam.[6] The star itself is more massive than the Sun, and is nearly twice the Sun's radius. It is also slightly metal-rich, a major factor in the formation of planetary systems. Kepler-7's planet was presented on January 4, 2010 at a meeting of the American Astronomical Society.

Nomenclature and discovery[edit]

Kepler-7 received its name because it was the home to the seventh planetary system discovered by the NASA-led Kepler Mission, a project aimed at detecting terrestrial planets that transit, or pass in front of, their host stars as seen from Earth.[7] The planet orbiting Kepler-7 was the fourth planet to be discovered by the Kepler spacecraft; the first three planets combed from Kepler's data had been previously discovered, and were used to verify the accuracy of Kepler's measurements.[8] Kepler-7b was announced to the public on January 4, 2010 at the 215th meeting of the American Astronomical Society in Washington, D.C. along with Kepler-4b, Kepler-5b, Kepler-6b, and Kepler-8b. Kepler-7b was noted for its unusually and extremely low density.[6]

The planet's initial discovery by Kepler was verified by additional observations made at observatories in Hawaii, Texas, Arizona, California, and the Canary Islands.[9]

Characteristics[edit]

Kepler-7 is a sunlike star that is 1.347 Msun and 1.843 Rsun. This means that the star is about 35% more massive and 84% wider than the Sun. The star is estimated to be 3.5 (± 1) billion years old. It is also estimated to have a metallicity of [Fe/H] = 0.11 (± 0.03), meaning that Kepler-7 is approximately 30% more metal-rich than the Sun; metallicity plays a significant role in the formation of planetary systems, as metal-rich stars tend to be more likely to have planets in orbit.[10] The star's effective temperature is 5933 (± 44) K.[11] In comparison, the 4.6 billion-year-old Sun[12] releases less heat, with an effective temperature of 5778 K.[13]

A picture showing the relative sizes of the first five planets discovered by Kepler. Kepler-7b is the largest, highlighted in yellow.

The star has an apparent magnitude of 13,[2] meaning that it is extremely dim as seen from Earth. It cannot be seen with the naked eye.[8] It is estimated to lie at approximately 3090 light years from the Solar System.[1]

There is a star that is 4 magnitudes dimmer located 1.90 arcseconds away, whether this a gravitationally bound companion star or a chance optical alignment is unknown.[14]

Planetary system[edit]

Kepler-7b is the only planet that has been discovered in Kepler-7's orbit. It is .433 MJ and 1.478 RJ, meaning it is 43% the mass of planet Jupiter, but is nearly three halves its size. With a density of .166 grams/cc,[8] the planet is approximately 17% the density of water. This is comparable to styrofoam.[6] At a distance of .06224 AU from its host star, Kepler-7b completes an orbit around Kepler-7 every 4.8855 days.[8] Planet Mercury, however, orbits the Sun at .3871 AU, and takes approximately 87.97 days to complete one orbit.[15] Kepler-7b's eccentricity is assumed to be 0, which would give Kepler-7b a circular orbit by definition.[8]

The Kepler-7 planetary system[8]
Companion
(in order from star)
Mass Semimajor axis
(AU)
Orbital period
(days)
Eccentricity Inclination Radius
b 0.433 MJ 0.06224 4.8855 0 1.478 RJ

See also[edit]

References[edit]

  1. ^ a b c d e f Brown, A. G. A.; et al. (Gaia collaboration) (August 2018). "Gaia Data Release 2: Summary of the contents and survey properties". Astronomy & Astrophysics. 616. A1. arXiv:1804.09365. Bibcode:2018A&A...616A...1G. doi:10.1051/0004-6361/201833051. Gaia DR2 record for this source at VizieR.
  2. ^ a b c Henden, A. A.; et al. (2016). "VizieR Online Data Catalog: AAVSO Photometric All Sky Survey (APASS) DR9 (Henden+, 2016)". VizieR On-line Data Catalog: II/336. Originally Published in: 2015AAS...22533616H. 2336. Bibcode:2016yCat.2336....0H.Vizier catalog entry
  3. ^ a b "Kepler-7". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-11-24.
  4. ^ a b c Skrutskie, M. F.; et al. (2006). "The Two Micron All Sky Survey (2MASS)". The Astronomical Journal. 131 (2): 1163–1183. Bibcode:2006AJ....131.1163S. doi:10.1086/498708.Vizier catalog entry
  5. ^ a b Latham, David W.; et al. (2010). "Kepler-7b: A Transiting Planet with Unusually Low Density". The Astrophysical Journal. 713 (2): L140–L144. arXiv:1001.0190. Bibcode:2010ApJ...713L.140L. doi:10.1088/2041-8205/713/2/L140.
  6. ^ a b c Rich Talcott (5 January 2010). "215th AAS meeting update: Kepler discoveries the talk of the town". Astronomy.com. Astronomy magazine. Retrieved 27 February 2011.
  7. ^ Johnson, Michele, ed. (2018-10-30). "Mission overview". www.nasa.gov. NASA. Retrieved 2018-11-24.
  8. ^ a b c d e f "Summary Table of Kepler Discoveries". NASA. 2010-01-04. Retrieved 2010-01-06.
  9. ^ "NASA's Kepler Space Telescope Discovers its FIrst Five Exoplanets". NASA. 4 January 2010. Retrieved 27 February 2011.
  10. ^ Henry Bortman (12 October 2004). "Extrasolar Planets: A Matter of Metallicity". Space Daily. Retrieved 27 February 2011.
  11. ^ "Notes for star Kepler-7". Extrasolar Planets Encyclopaedia. 2010. Archived from the original on 21 January 2011. Retrieved 27 February 2011.
  12. ^ Fraser Cain (16 September 2008). "How Old is the Sun?". Universe Today. Retrieved 27 February 2011.
  13. ^ David Williams (1 September 2004). "Sun Fact Sheet". Goddard Space Flight Center. NASA. Retrieved 27 February 2011.
  14. ^ Hirsch, Lea A.; et al. (2017). "Assessing the Effect of Stellar Companions from High-resolution Imaging of Kepler Objects of Interest". The Astronomical Journal. 153 (3). 117. arXiv:1701.06577. Bibcode:2017AJ....153..117H. doi:10.3847/1538-3881/153/3/117.
  15. ^ David Williams (17 November 2010). "Mercury Fact Sheet". Goddard Space Flight Center. NASA. Retrieved 27 February 2011.

External links[edit]

Boyle, Alan. "How astronomers mapped the patchy clouds of an alien world". NBC News. Retrieved 3 October 2013.

Coordinates: Sky map 19h 14m 19.6s, +41° 5′ 23.3″