Kepler-90
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Star Kepler-90 |
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| Comparison of the solar system and Kepler-90 | |||||
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Observation dates equinox : J2000.0 , epoch : J2000.0 |
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| Constellation | Dragon | ||||
| Right ascension | 18 h 57 m 44.04 s | ||||
| declination | + 49 ° 18 ′ 18.5 ″ | ||||
| Apparent brightness | 13.9 likes | ||||
| Typing | |||||
| Known exoplanets | 8th | ||||
| Spectral class | F6 - G6 | ||||
| Astrometry | |||||
| parallax | (1.15 ± 0.01) mas | ||||
| distance | (2,800) ly 870 pc |
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| Proper movement | |||||
| Rec. Share: | (−4.38 ± 0.03) mas / a | ||||
| Dec. portion: | (−3.21 ± 0.03) mas / a | ||||
| Physical Properties | |||||
| Dimensions | 1.13 +0.18−0.0 M ☉ | ||||
| radius | 1.2 ± 0.1 R ☉ | ||||
| Luminosity |
1.60 ± 0.5 L ☉ |
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| Effective temperature | 5930 ± 320 K | ||||
| Metallicity [Fe / H] | −0.17 ± 0.21 | ||||
| Age | > 100 M a | ||||
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Other names and catalog entries |
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Kepler-90 (also KOI-351 and KIC 11442793 ) is a main sequence star in the Milky Way about 2800 light-years away . It is possibly a sun-like star and is slightly larger and more luminous than the sun.
According to the research status of December 2017, Kepler-90 has a planetary system with eight known planets and is therefore the only known system with as many known planets as the solar system . At the same time, it is also the system with the most known exoplanets, which it was at the time of its first publication in October 2013 with seven planets. The data for the six inner planets indicate compact super-earths or mini- Neptunes , while the two outer planets can be classified as large gas planets (gas giants). The known part of the planetary system around Kepler-90 is much more densely packed than the solar system: the orbit of the outermost known planet and thus the entire known system has roughly the dimensions of the earth's orbit around the sun.
Planets
All planets were discovered using the transit method. This enables a reliable determination of the size of the planets, but no direct measurement of their masses. Since the first seven planets were discovered at the same time, their designation follows the distance to the star, Kepler-90b is the innermost and Kepler-90h the outermost of those seven planets. Kepler-90i orbits the star between the orbits of Kepler-90c and -d.
| planet |
Discovery year |
Orbital time [d] |
Major semi-axis [AE] |
Estimated surface temperature [K] |
Inclination [degree] |
Transit time [h] |
Radius [R E ] |
roughly estimated mass |
|---|---|---|---|---|---|---|---|---|
| b | 2013 | 7.00815 ± 1.9e-05 | 0.074 ± 0.016 | 1056.0 | 89.4 ± 1.5 | 3.99 ± 0.15 | 1.31 ± 0.17 | ~ 3 M E |
| c | 2013 | 8.71938 ± 2.7e-05 | 0.089 ± 0.012 | 981.0 | 89.68 ± 0.74 | 4.41 ± 0.18 | 1.19 ± 0.14 | ~ 3 M E |
| d | 2013 | 59.7367 ± 3.8e-04 | 0.32 ± 0.05 | 518.0 | 89.71 ± 0.29 | 8.4 ± 0.19 | 2.87 ± 0.3 | ~ 10 M E |
| e | 2013 | 91.939 ± 7.3e-04 | 0.42 ± 0.06 | 448.0 | 89.79 ± 0.19 | 9.71 ± 0.19 | 2.66 ± 0.29 | ~ 10 M E |
| f | 2013 | 124.914 ± 1.9e-03 | 0.48 ± 0.09 | 592.0 | 89.77 ± 0.31 | 10.94 ± 0.25 | 2.88 ± 0.52 | ~ 10 M E |
| G | 2013 | 210.607 ± 4.3e-04 | 0.71 ± 0.08 | 340.0 | 89.80 ± 0.06 | 12.593 ± 0.045 | 8.1 ± 0.8 | ~ 1.7 M N ≈ 0.09 M J ≈ 30 M E |
| H | 2013 | 331.6006 ± 3.7e-04 | 1.01 ± 0.11 | 292.0 | 89.6 ± 1.3 | 14.737 ± 0.046 | 11.3 ± 1.0 | ~ 0.8 M J ≈ 250 M E |
| i | 2017 | 14.44912 ± 2.0e-04 | 0.12 ± 0.02 | 709 ± 75 | 89.2 ± 1.3 | 2.80 ± 0.31 | 1.32 ± 0.21 | ~ 3 M E |
M E = Earth mass / M N = Neptune mass / M J = Jupiter mass
Kepler-90b and -c
Kepler-90b has a radius about 30% larger than the earth, Kepler-90c about 20%. The orbits show a 5: 4 resonance ; this means that in the time that Kepler-90b orbits the star five times, Kepler-90c orbits the star exactly four times. This means that the planets always meet in the same positions. There are similar resonances with three of the four Galilean moons of Jupiter . No indications have yet been shown for further dynamic interactions with the other planets.
Kepler-90d, -e and -f
Planet Kepler-90d orbits the star with a period of 60 days. This is comparable to Mercury's orbital period around the sun. The radius is about three times that of the earth. He's probably a super-earth or a mini- Neptune . Since the mass is only estimated, it is not yet possible to decide which of the two classes this planet belongs to.
Kepler-90f is similar in size to Kepler-90d, Kepler-90e should be a bit smaller. The orbits of these three planets are almost in 2: 3: 4 resonance and are approximately circular.
Kepler-90g and -h
The gas giants Kepler-90g and Kepler-90h have an approximately 8-fold and 11-fold radius of the earth and orbit the central star in 211 and 332 days, respectively.
Kepler-90g could possibly be orbited by a moon .
Kepler-90i
Kepler-90i was discovered in 2017 during an analysis of the data recorded by the Kepler space telescope in the period from May 2009 to May 2013 using deep learning (a method attributed to Artificial Intelligence ) by showing its very weak transit signals (darkening of the central star) for the first time that had escaped attention in previous analyzes.
Comparison with the solar system
In addition to the same number of known planets as of December 2017 (8 each), a parallel to the solar system can be seen in the fact that two gas giants each orbit the central star outside a sequence of smaller planets: six in the Kepler-90 system, the four planets Mercury , Venus , Earth and Mars in the solar system. In the solar system, however, Jupiter is the fifth planet from the inside, the most massive, in the system Kepler-90 (as far as known) the outermost. Furthermore, despite the similar properties of the central stars, the inner planets in the solar system are much smaller and the orbits of the gas giants in the solar system are considerably larger (orbital times Jupiter 4,333 days and Saturn 10,559 days, compared to 211 and 332 days for Kepler-90g and -h) and also separated by a distinct gap (the asteroid belt ). Thus, one cannot speak of a similarity of the systems in terms of orbital radius and mass distribution of the planets.
Web links
Individual evidence
- ↑ a b c Kepler-90. In: SIMBAD . Center de Données astronomiques de Strasbourg , accessed December 7, 2018 .
- ↑ KIC 11442793. In: VSX. AAVSO, accessed December 7, 2018 .
- ↑ a b c d Kepler-90 i. In: Extrasolar Planets Encyclopaedia . Retrieved December 7, 2018 .
- ↑ a b c Juan Cabrera, Sz.Csizmadia, H. Lehmann, R. Dvorak, D. Gandolfi, H. Rauer, A. Erikson, C. Dreyer, Ph. Eigmueller, A. Hatzes: The Planetary System to KIC 11442793: A Compact Analogue to the Solar System. (PDF) In: Astrophysical Journal (accepted for publication). November 11, 2013, accessed December 17, 2017 . doi : 10.1088 / 0004-637X / 781/1/18 , arxiv : 1310.6248
- ↑ a b Second solar system discovered. German Aerospace Center , October 28, 2013, accessed on December 17, 2017 .
- ↑ Joseph R. Schmitt et al .: Planet Hunters. VI: An Independent Characterization of KOI-351 and Several Long Period Planet Candidates from the Kepler Archival Data. (PDF) In: Astronomical Journal (accepted for publication). June 30, 2014, accessed December 17, 2017 . doi : 10.1088 / 0004-6256 / 148/2/28 , arxiv : 1310.5912
- ↑ Christopher J. Shallue, Andrew Vanderburg: Identifying Exoplanets with Deep Learning: A Five Planet Resonant Chain around Kepler-80 and an Eighth Planet around Kepler-90. (PDF) In: Astronomical Journal (accepted for publication). December 13, 2017. Retrieved December 17, 2017 . arxiv : 1712.05044
- ↑ AI discovers star with eight planets. scinexx , December 15, 2017, accessed December 17, 2017 .