Kepler-186

Last updated
Kepler-186 [1]
Kepler-186.svg
Kepler-186 is indicated by the red circle
(2MASS J band image)
Observation data
Epoch J2000.0       Equinox J2000.0
Constellation Cygnus
Right ascension 19h 54m 36.6535s [2]
Declination +43° 57′ 18.026″ [2]
Apparent magnitude  (V)15.29 [3]
Characteristics
Evolutionary stage Main sequence
Spectral type M1V [4]
Astrometry
Proper motion (μ)RA: 2.171(18)  mas/yr [2]
Dec.: −4.363(20)  mas/yr [2]
Parallax (π)5.6336 ± 0.0169  mas [2]
Distance 579 ± 2  ly
(177.5 ± 0.5  pc)
Details
Mass 0.544 ± 0.02 [4]   M☉
Radius 0.523 ± 0.02 [4]   R☉
Luminosity (bolometric)0.055 +0.011
−0.006 [4]   L☉
Temperature 3755 ± 90 [4]   K
Metallicity [Fe/H]−0.26 ± 0.12 [4]   dex
Rotation 34.404±0.075 days [5]
Age 4.0 ± 0.6 [4]   Gyr
Other designations
KIC   8120608, KOI-571,
2MASS J19543665+4357180, Gaia DR2 2079000330051813504
Database references
SIMBAD data

Kepler-186 is a main-sequence M1-type dwarf star, located 177.5 parsecs (579 light years) away in the constellation of Cygnus. The star is slightly cooler than the sun, with roughly half its metallicity. It is known to have five planets, including the first Earth-sized world discovered in the habitable zone: Kepler-186f. [6] The star hosts four other planets discovered so far, though they all orbit interior to the habitable zone.

Contents

Star

A number of previously unknown measurements of the star are known. [7] [8] In the infrared/microwave EM spectrum [1] its H band magnitude is 11.605, J band magnitude is 12.473, and its K band magnitude is 11.605. In the visual Photometric system magnitude it is 14.90(R)(towards the red end of the visual spectrum) and 16.40(B)(the blue end of the spectrum) [7] (see also Apparent magnitude.) It is a BY Draconis variable changing brightness slightly, probably from star-spots, with a period of 33.695 days. [9]

The star is an M-type red dwarf, bordering on being a K-type orange dwarf, with a mass 0.544 times that of the Sun's and a density of 5.29  g/cm3 . [4]

Discovery of a planetary system

Within two first years of gathered data, the signals of four inner planetary candidates were found. Discussion of planets in the system was taking place in August and November 2013. [10] In February 2014, those planets were confirmed through the "verification by multiplicity" method. The fifth outermost candidate was confirmed in the same manner in April 2014. [11] The possibility that the signals in the light curve of the star were actually from something else has been ruled out by an investigation with the W. M. Keck and Gemini Observatories, using speckle imaging and adaptive optics techniques, which, while unable to resolve the planets, were able to rule out other possibilities than the system of planets. [12]

Planetary system

The Kepler-186 planetary system
Companion
(in order from star)		 Mass Semimajor axis
(AU)		 Orbital period
(days)		 Eccentricity Inclination Radius
b ~1.24  M🜨 0.03783.8867907<0.2483.65° 1.08  R🜨
c~2.1  M🜨 0.05747.267302<0.2485.94° 1.25  R🜨
d~2.54  M🜨 0.086113.342996<0.2587.09° 1.39  R🜨
e ~2.15  M🜨 0.121622.407704<0.2488.24° 1.33  R🜨
f ~1.71  M🜨 0.432129.9444<0.0489.9° 1.17  R🜨

The five planets discovered around Kepler-186 are all expected to have a solid surface. The smallest one, Kepler-186b, is only 8% larger than Earth, while the largest one, Kepler-186d, is almost 40% larger.

The four innermost planets are probably tidally locked, but Kepler-186f is farther out, where the star's tidal effects are much weaker, so there may not have been enough time for its spin to slow down that much. Because of the very slow evolution of red dwarf stars, the age of the Kepler-186 system is poorly constrained, although it is likely to be greater than a few billion years. [13] There is a roughly 50-50 chance it is tidally locked. Since it is closer to its star than Earth is to the Sun, it will probably rotate much more slowly than Earth; its day could be weeks or months long (see Tidal effects on rotation rate, axial tilt and orbit). [14]

Planetary formation simulations have also shown that there could be one additional non-transiting low-mass planet between Kepler-186e and Kepler-186f. If this planet exists, it is likely not much more massive than Earth. If it were, its gravitational influence would likely prevent Kepler-186f from transiting. [13] Conjectures involving the Titius–Bode law, (and the related Dermott's law) indicate that there could be several remaining planets to be found in the system - two small ones between e and f and another larger one outside of f. [15] That hypothetical outer planet must have an orbital radius beyond 16.4 AU for planetary system to remain stable. [16]

The low metallicity of the star at a metallicity (dex) of -0.26, or to put it another way, about half that of the Sun's, [6] is associated with a decreased chance of planets overall and giant planets specifically but an increased chance of Earth sized planets, in a general study of stars. [17]

Naming

Kepler project

As the Kepler space telescope observational campaign progressed initial identifications of systems were entered in the Kepler Input Catalog (KIC), and then progressed as a candidate host of planets as Kepler Object of Interest (KOI). Thus Kepler-186 started as KIC 8120608 and then was identified as KOI 571. [18]

Outside the Kepler project

Outside of the Kepler project, the 2MASS survey catalogued this star as 2MASS J19543665+4357180. [1]

See also

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<span class="mw-page-title-main">Kepler-62</span> K-type star in the constellation Lyra

Kepler-62 is a K-type main sequence star cooler and smaller than the Sun, located roughly 980 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.

<span class="mw-page-title-main">Kepler-62f</span> Super-Earth orbiting Kepler-62

Kepler-62f is a super-Earth exoplanet orbiting within the habitable zone of the star Kepler-62, the outermost of five such planets discovered around the star by NASA's Kepler space telescope. It is located about 980 light-years from Earth in the constellation of Lyra.

<span class="mw-page-title-main">Kepler-69</span> Star in the constellation Cygnus

Kepler-69 is a G-type main-sequence star similar to the Sun in the constellation Cygnus, located about 2,390 ly (730 pc) from Earth. On April 18, 2013 it was announced that the star has two planets. Although initial estimates indicated that the terrestrial planet Kepler-69c might be within the star's habitable zone, further analysis showed that the planet very likely is interior to the habitable zone and is far more analogous to Venus than to Earth and thus completely inhospitable.

<span class="mw-page-title-main">Kepler-90</span> Star in the constellation Draco, orbited by eight planets

Kepler-90, also designated 2MASS J18574403+4918185, is a F-type star located about 2,790 light-years (855 pc) from Earth in the constellation of Draco. It is notable for possessing a planetary system that has the same number of observed planets as the Solar System.

<span class="mw-page-title-main">Kepler-138</span> Red dwarf in the constellation Lyra

Kepler-138, also known as KOI-314, is a red dwarf located in the constellation Lyra, 219 light years from Earth. It is located within the field of vision of the Kepler spacecraft, the satellite that NASA's Kepler Mission used to detect planets transiting their stars.

<span class="mw-page-title-main">Kepler-186f</span> Terrestrial exoplanet orbiting Kepler-186

Kepler-186f is an Earth-sized exoplanet orbiting within the habitable zone of the red dwarf star Kepler-186, the outermost of five such planets discovered around the star by NASA's Kepler space telescope. It is located about 580 light-years from Earth in the constellation of Cygnus.

<span class="mw-page-title-main">Kepler-442b</span> 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.

<span class="mw-page-title-main">Kepler-452</span> G-type main-sequence star in the constellation Cygnus

Kepler-452 is a G-type main-sequence star located about 1,810 light-years away from Earth in the Cygnus constellation. Although similar in temperature to the Sun, it is 20% brighter, 3.7% more massive and 11% larger. Alongside this, the star is approximately six billion years old and possesses a high metallicity.

Kepler-186e is a confirmed exoplanet orbiting the red dwarf star Kepler-186, approximately 582 light years away from Earth in the constellation of Cygnus. It is near the optimistic habitable zone but probably not in it, possibly making it have a runaway greenhouse effect, like Venus. The exoplanet was found by using the transit method, in which the dimming effect that a planet causes as it crosses in front of its star is measured. Four additional planets orbiting the star were also discovered.

Kepler-1229 is a red dwarf star located about 875 light-years (268 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-442 is a K-type main-sequence star approximately 1,196 light years from Earth in the constellation Lyra. It is located 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 January 6, 2015, along with the stars of Kepler-438 and Kepler-440, it was announced that the star has an extrasolar planet orbiting within the habitable zone, named Kepler-442b.

TOI-700 is a red dwarf 101.4 light-years away from Earth located in the Dorado constellation that hosts TOI-700 d, the first Earth-sized exoplanet in the habitable zone discovered by the Transiting Exoplanet Survey Satellite (TESS).

<span class="mw-page-title-main">TOI-700 d</span> Goldilocks terrestrial planet orbiting TOI-700

TOI-700 d is a near-Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the red dwarf TOI-700, the outermost planet within the system. It is located roughly 101.4 light-years (31.1 pc) away from Earth in the constellation of Dorado. The exoplanet is the first Earth-sized exoplanet in the habitable zone discovered by the Transiting Exoplanet Survey Satellite (TESS).

<span class="mw-page-title-main">Kepler-1649c</span> Earth-size exoplanet orbiting Kepler-1649

Kepler-1649c is an Earth-sized exoplanet, likely rocky, orbiting within the habitable zone of the red dwarf star Kepler-1649, the outermost planet of the planetary system discovered by Kepler’s space telescope. It is located about 301 light-years (92 pc) away from Earth, in the constellation of Cygnus.

Kepler-737b is a super-Earth exoplanet 669 light years away. There is a chance it could be on the inner edge of the habitable zone.

References

  1. 1 2 3 SIMBAD, KIC8120608
  2. 1 2 3 4 5 Vallenari, A.; et al. (Gaia collaboration) (2023). "Gaia Data Release 3. Summary of the content and survey properties". Astronomy and Astrophysics. 674: A1. arXiv: 2208.00211 . Bibcode:2023A&A...674A...1G. doi: 10.1051/0004-6361/202243940 . S2CID   244398875. Gaia DR3 record for this source at VizieR.
  3. ↑ Souto, Diogo; et al. (2017). "Chemical Abundances of M-dwarfs from the APOGEE Survey. I. The Exoplanet Hosting Stars Kepler-138 and Kepler-186". The Astrophysical Journal. 835 (2): 239. arXiv: 1612.01598 . Bibcode:2017ApJ...835..239S. doi: 10.3847/1538-4357/835/2/239 . S2CID   73634716.
  4. 1 2 3 4 5 6 7 8 "Kepler-186 f". NASA Exoplanet Archive. Retrieved 19 July 2016.
  5. ↑ McQuillan, A.; Mazeh, T.; Aigrain, S. (2013). "Stellar Rotation Periods of The Kepler objects of Interest: A Dearth of Close-In Planets Around Fast Rotators". The Astrophysical Journal Letters. 775 (1). L11. arXiv: 1308.1845 . Bibcode:2013ApJ...775L..11M. doi:10.1088/2041-8205/775/1/L11. S2CID   118557681.
  6. 1 2 Quintana, E. V.; Barclay, T.; Raymond, S. N.; Rowe, J. F.; Bolmont, E.; Caldwell, D. A.; Howell, S. B.; Kane, S. R.; Huber, D.; Crepp, J. R.; Lissauer, J. J.; Ciardi, D. R.; Coughlin, J. L.; Everett, M. E.; Henze, C. E.; Horch, E.; Isaacson, H.; Ford, E. B.; Adams, F. C.; Still, M.; Hunter, R. C.; Quarles, B.; Selsis, F. (2014-04-18). "An Earth-Sized Planet in the Habitable Zone of a Cool Star". Science . 344 (6181): 277–280. arXiv: 1404.5667 . Bibcode:2014Sci...344..277Q. doi:10.1126/science.1249403. PMID   24744370. S2CID   1892595. free version = http://www.nasa.gov/sites/default/files/files/kepler186_main_final.pdf
  7. 1 2 VizieR Detailed Page for 2MASS 19543665+4357180, "This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation."
  8. ↑ VizieR Detailed Page, KIC 8120608, Kepler Input Catalog (Kepler Mission Team, 2009)
  9. ↑ "KIC 8120608". The International Variable Star Index, Version 1.1 [C]. American Association of Variable Star Observers (AAVSO). Retrieved April 19, 2014.
  10. ↑ Glister, Paul (5 November 2013). "Earth-Sized Planets in Habitable Zone Common". Centauri Dreams. Archived from the original on 19 April 2014. See comment by "Holger 16 November 2013 at 14:21".
    ^redakce ["editor"] (6 August 2013). "Kepler (asi) našel obyvatelnou planetu o velikosti Země" [Kepler (probably) found a habitable planet the size of Earth] (in Czech). exoplanety.cz. Archived from the original on 20 August 2013.{{cite web}}: |author= has generic name (help)
    ^ "Kepler: Erster Kandidat einer habitablen Exoerde Veröffentlicht" [Kepler: First candidate of a habitable Exoplanet Published]. Zauber der Sterne [Magic of the stars] (in German). 19 August 2013. Archived from the original on 27 September 2013.
    ^Bovaird, Timothy; Lineweaver, Charles H. (2013). "Exoplanet Predictions Based on the Generalised Titius-Bode Relation". Monthly Notices of the Royal Astronomical Society. 435 (2): 14–15. arXiv: 1304.3341 . Bibcode:2013MNRAS.435.1126B. doi: 10.1093/mnras/stt1357 . S2CID   15620163.
  11. ↑ Wall, Mike (26 February 2014). "Population of Known Alien Planets Nearly Doubles as NASA Discovers 715 New Worlds". Space.com . Retrieved 26 February 2014.
  12. ↑ Elisa Quintana; Steve Howell (Apr 17, 2014). "First potentially habitable Earth-sized planet confirmed by Gemini and Keck Observatories". Press Release. Gemini Observatory. Retrieved April 23, 2014.
  13. 1 2 Formation, tidal evolution and habitability of the Kepler-186 system, Emeline Bolmont, Sean N. Raymond, Philip von Paris, Franck Selsis, Franck Hersant, Elisa V. Quintana, Thomas Barclay, (Submitted on 16 Apr 2014)
  14. ↑ Staff. "Kepler 186f - A Planet in the Habitable Zone (video)". Hangout On-Air. SETI Institute. Archived from the original on 2014-04-18. Retrieved 2014-04-18.
  15. ↑ Bovaird, Timothy; Lineweaver, Charles H. (2013). "Exoplanet Predictions Based on the Generalised Titius-Bode Relation". Monthly Notices of the Royal Astronomical Society. 435 (2): 14–15. arXiv: 1304.3341 . Bibcode:2013MNRAS.435.1126B. doi: 10.1093/mnras/stt1357 . S2CID   15620163.
  16. ↑ Becker, Juliette C.; Adams, Fred C. (2017), "Effects of Unseen Additional Planetary Perturbers on Compact Extrasolar Planetary Systems", Monthly Notices of the Royal Astronomical Society, 468 (1): 549–563, arXiv: 1702.07714 , Bibcode:2017MNRAS.468..549B, doi: 10.1093/mnras/stx461 , S2CID   119325005
  17. ↑ J. S. Greaves; D. A. Fischer; M. C. Wyatt (November 10, 2005). "Metallicity, debris discs and planets" (PDF). Monthly Notices of the Royal Astronomical Society. 366 (1): 283–286. Bibcode:2006MNRAS.366..283G. doi: 10.1111/j.1365-2966.2005.09848.x . ISSN   1365-2966 . Retrieved April 20, 2014.
  18. ↑ Rowe, Jason F.; et al. (2014). "Validation of Kepler's Multiple Planet Candidates. III: Light Curve Analysis & Announcement of Hundreds of New Multi-planet Systems (Revision 8.0)". The Astrophysical Journal. 784 (1): 45. arXiv: 1402.6534 . Bibcode:2014ApJ...784...45R. doi:10.1088/0004-637X/784/1/45. S2CID   119118620.
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