Kepler-42

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Star
Kepler-42
Artist's impression of Kepler-42 and its planetary system
Artist's impression of Kepler-42 and its planetary system
AladinLite
Observation
dates equinox :  J2000.0 , epoch : J2000.0
Constellation swan
Right ascension 19 h 28 m 52.57 s
declination + 44 ° 37 ′ 9 ″
Apparent brightness 16.12 mag
Typing
Known exoplanets 3
R − I index (2.26) 
Spectral class M5 V
Astrometry
Radial velocity −84.48 ± 0.2 km / s
parallax (24.93 ± 0.04)  mas
distance (130.77 ± 0.22)  Lj
40.11 ± 0.06  pc
Proper movement 
Rec. Share: (93.13 ± 0.07)  mas / a
Dec. portion: (−417.42 ± 0.07)  mas / a
Physical Properties
Dimensions 0.13 ± 0.05  M ☉
radius 0.17 ± 0.04  R ☉
Luminosity

2.4 ± 0.2 × 10 −3  L ☉

Effective temperature 3,068 ± 174  K
Metallicity [Fe / H] −0.48 ± 0.17
Other names
and catalog entries
2MASS catalog 2MASS J19285255 + 4437096 [1]
Other names KIC 8561063, KOI-961, Kepler-42, WISE J192852.66 + 443704.5

Kepler-42 (also KOI-961 ) is a red dwarf in the constellation Schwan , which is about 130 light-years from the sun is removed. The star has a planetary system with three known exoplanets .

properties

Kepler-42 has only about 13% of the solar mass and about 17% of the solar radius . It is therefore somewhat smaller and less massive than Barnard's Arrow Star , which is one of the sun's closest neighbors. Like this, the Kepler-42 also has a high intrinsic motion . Its metallicity is about a third of that of the sun.

Planetary system

Comparison of Kepler-42 (with the three planets) and Jupiter (with the Galilean moons )

With the Kepler space telescope , three planets orbiting the star could be detected using the transit method . The discovery was announced in January 2012.

All three planets have a smaller radius than Earth and are among the smallest exoplanets discovered by early 2012. The outermost planet Kepler-42d has a radius slightly larger than Mars in the solar system . The planets orbit their central star at a very short distance and within a very short time. The innermost planet, Kepler-42c, takes less than half an earth day to orbit the star. All planets are probably rock planets , but because of their orbits close to the star, they are much too hot and are therefore outside the habitable zone of Kepler-42.

The structure of the planetary system of Kepler-42 is similar to the planet Jupiter and its four large moons Io , Europa , Ganymed , and Callisto . At the time of its discovery, it was the most compact known planetary system.

Planetary system from Kepler-42
Planet
(by distance from the star) 		Discovery
(year) 		Radius
(in ) 		Cycle time
(in days) 		Major semi-axis
(in AU )
Kepler-42c 2012 0.73 ± 0.20 0.45328509 ± 0.00000097 0.0060
Kepler-42b 2012 0.78 ± 0.22 1.2137672 ± 0.0000046 0.0116
Kepler-42d 2012 0.57 ± 0.18 1.865169 ± 0.000014 0.0154

Web links

Commons : Kepler-42  - Collection of pictures, videos and audio files

Individual evidence

  1. ↑ a b c d KOI-961. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed December 7, 2018 .
  2. ↑ Planet Kepler-42 b. In: Extrasolar Planets Encyclopaedia . Retrieved December 7, 2018 .
  3. ↑ a b c Kepler-42. In: NASA Exoplanet Archive . Retrieved December 7, 2018 .
  4. ↑ a b c d e f g h Muirhead et al .: Characterizing the Cool KOIs III. KOI-961: A Small Star with Large Proper Motion and Three Small Planets . arxiv : 1201.2189 .
  5. ↑ a b c National Aeronautics and Space Administration: NASA's Kepler Mission Finds Three Smallest Exoplanets. Retrieved May 29, 2015 .