Astronomy:Kepler-737b

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Kepler-737b
Discovery
Discovered byHARPS, Kepler space telescope
Discovery dateMay 10, 2016
Transit
Designations
KOI-947.01, KIC 9710326 b, Gaia DR2 2126820324123177472 b
Orbital characteristics
0.1422 AU
Orbital period29.5992 days
StarKepler-737
Physical characteristics
Mean radius1.96 R⊕
Mass~4.5 M⊕
Mean density~3.3 g/cm3
Physics298 K (25 °C; 77 °F)


Kepler-737b is a super-Earth exoplanet 669 light years away.[1] There is a chance it could be on the inner edge of the habitable zone.[2]

Physical properties

Mass, radius and temperature

Kepler-737b is an exoplanet with 1.96 R⊕ (0.175 RJ). Its mass is unknown, but is estimated at 4.5 M⊕ based on a mass-radius relationship.[1][3][4] If the 4.5-earth mass estimate is correct, this gives the planet an approximate density of 3.3 times that of water, giving it the possibility of being a mini-Neptune or, more favorable to habitability, a water world. Due to its stellar flux 121% that of Venus, it may be a smaller version of GJ 1214b, a classic superpressured water world. The planet's equilibrium temperature is 298 K (25 °C).

Star

The star's designations include Kepler-737 and KOI-947.[2] It is an early M-star. The mass is 0.51 solar masses and its radius is 0.48 times that of the Sun.[2][5] The temperature of the star is 3813 K and its metallicity is -0.24, significantly lower than the Sun's.[2] The host star's age is 3.89 billion years, 680 million years younger than the Sun.[6]

Orbit

Kepler-737b orbits its star once every 28.5992 days.[2] It may be within the inner part of the habitable zone, depending on the habitable zone model used. The conservative model/models place it over 1 Earth flux level outside of the habitable zone, but some very optimistic models place it inside the far inner section of the extended habitable zone. If it is not a mini-Neptune, then it might have a small chance of being habitable. It would be substantially hotter than Earth, due to its stellar flux 2.297 times that of Earth,[3] greater than that of Venus,[7] and resulting equilibrium temperature of 298 K (25 °C; 77 °F).[1]

Discovery

Kepler-737b is a confirmed exoplanet that was found by Kepler using the transit method.[2] It was confirmed on May 10,[2] 2016.[1]

Nomenclature

Kepler-737b is also known as KOI-947.01, KIC 9710326 b, and Gaia DR2 2126820324123177472 b.[2] KOI means "Kepler Object of Interest" and KIC means "Kepler Input Catalog". Gaia is a European satellite that was launched on December 19, 2013.[8]

Habitability

Main page: Astronomy:Habitability of red dwarf systems

With a stellar flux 2.297 times that of Earth,[3] greater than that of Venus,[7] Kepler-737b is unlikely to be habitable. However, Kepler-737b is considered to be in the habitable zone by the Open Exoplanet Catalogue,[2] based on an extremely optimistic habitable zone model that also places Venus in the habitable zone.[9] Due to its equilibrium temp. of 298 K, with and earth-like GE it would be about sixty degrees Celsius, and with twice its GE, ninety degrees. It is likely tidally locked due to its short orbit; a tidally locked planet would have one side facing the star permanently while the other would be in constant darkness.[10] If Kepler-737b has little or no atmosphere, this could make one side too hot to live on, and the other too cold. However, there may be a "sweet spot" in between the two, where liquid water can exist. This spot would be the planet's terminator line. Kepler-737b may instead have atmospheric circulation that would distribute the heat around the planet, potentially making a large portion of it habitable,[11] although given its stellar flux the most likely scenario is that the planet's surface is too hot to be habitable. Water on Kepler-737b's surface could also distribute heat.[12]

Kepler-737b's density is unknown, so it could either be a rocky super-Earth or a mini-Neptune. The fact that the planet is quite likely to have no magnetic field[citation needed] could spark adaptations to the relatively high radiation level, such as a thick shell of a substance that could repel the radiation or tardigrade-like DNA. In most earthly creatures, DNA is damaged permanently, but with tardigrades, DNA is repairable after being damaged by deadly radiation.[13]

There is a reduced chance of intelligent life on Kepler-737b due to the fair chance that it is a water world, with no dry land.[citation needed] It is likely substantially hotter than Earth, due to its stellar flux 2.297 times that of Earth[3] and resulting equilibrium temperature of 298 K (25 °C; 77 °F).[14] If ice caps exist, then they would likely be much smaller than Earth's, due to the temperature as well as to the possibility that Kepler-737b has more carbon dioxide in its atmosphere than Earth.[lower-alpha 1] It would have accreted the carbon dioxide by gravity or because water worlds are likely to have a lot of carbon dioxide in their atmospheres.[citation needed] More carbon dioxide in an atmosphere equalizes the temperature.

See also

Notes

  1. ↑ Does not include all possible factors.

References

  1. ↑ 1.0 1.1 1.2 1.3 "Exoplanet-catalog – Exoplanet Exploration: Planets Beyond our Solar System Kepler-737 b". https://exoplanets.nasa.gov/exoplanet-catalog/5111/kepler-737-b/. 
  2. ↑ 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 "Open Exoplanet Catalogue - Kepler-737 b". http://www.openexoplanetcatalogue.com/planet/Kepler-737%20b/. 
  3. ↑ 3.0 3.1 3.2 3.3 "Planetary Systems Composite Data". https://exoplanetarchive.ipac.caltech.edu/cgi-bin/TblView/nph-tblView?app=ExoTbls&config=PSCompPars. Retrieved 16 January 2022. 
  4. ↑ "About the Planetary Systems Composite Parameters Table". https://exoplanetarchive.ipac.caltech.edu/docs/pscp_about.html. Retrieved 16 January 2022. "If the Planetary Systems table does not have a value for the planetary radius, mass or density or a stellar luminosity, these values are calculated. See How the Archive Calculates Values in the Planetary Systems Composite Parameters Table for a detailed explanation." 
  5. ↑ "Kepler 737 Star Facts (Type, Distance, Colour, Radius, Location, Exoplanets & more)" (in en). 27 April 2019. https://www.universeguide.com/star/122022/kepler737. 
  6. ↑ "The Extrasolar Planet Encyclopaedia — Kepler-737 b". Extrasolar Planets Encyclopaedia. https://exoplanet.eu/catalog/kepler_737_b--2817/. 
  7. ↑ 7.0 7.1 HEC HZ hpcf.upr.edu
  8. ↑ "Gaia | Description & Facts" (in en). https://www.britannica.com/topic/Gaia-European-Space-Agency-satellite. 
  9. ↑ "Open Exoplanet Catalogue - Venus". http://www.openexoplanetcatalogue.com/planet/Venus/. 
  10. ↑ "Tidally locked exoplanets may be more common than previously thought" (in en). https://www.washington.edu/news/2017/08/14/tidally-locked-exoplanets-may-be-more-common-than-previously-thought/. 
  11. ↑ Hammond, Mark; Lewis, Neil T. (2021-03-30). "The rotational and divergent components of atmospheric circulation on tidally locked planets" (in en). Proceedings of the National Academy of Sciences 118 (13): e2022705118. doi:10.1073/pnas.2022705118. ISSN 0027-8424. PMID 33753500. Bibcode: 2021PNAS..11822705H. 
  12. ↑ Sutter, Paul (2021-03-08). "Can super-rotating oceans cool off extreme exoplanets?" (in en). https://www.space.com/super-rotating-oceans-extreme-exoplanets. 
  13. ↑ "Are tardigrades really aliens? | A World Unseen: the diversity of life" (in en-US). https://u.osu.edu/worldunseen/are-tardigrades-really-aliens/. 
  14. ↑ Guo, Xueying; Ballard, Sarah; Dragomir, Diana; Werner, Michael; Livingston, John; Gorjian, Varoujan (July 2019). "Temperate Super-Earths/Mini-Neptunes around M/K Dwarfs Consist of Two Populations Distinguished by Kepler and Spitzer Transit Depth Variations" (in en). The Astrophysical Journal 880 (1): 64. doi:10.3847/1538-4357/ab24be. ISSN 0004-637X. Bibcode: 2019ApJ...880...64G. 
  15. ↑ "GJ 832c: Habitable Super-Earth or Super-Venus?" (in en-US). 2014-06-27. https://www.drewexmachina.com/2014/06/27/gj-832c-habitable-super-earth-or-super-venus/. 

External links



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