Kepler-737b

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]

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
29.5992 days
StarKepler-737
Physical characteristics
Mean radius
1.96 R🜨
Mass~4.5 M🜨
Mean density
~3.3 g/cm3
Temperature298 K (25 Â°C; 77 Â°F)

    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 Â°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 Â°C; 77 Â°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 article: 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 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. 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 Â°C; 77 Â°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. More carbon dioxide in an atmosphere equalizes the temperature.

    See also

    Notes
    1. Does not include all possible factors.

    References
    1. "Exoplanet-catalog – Exoplanet Exploration: Planets Beyond our Solar System Kepler-737 b".
    2. "Open Exoplanet Catalogue - Kepler-737 b". www.openexoplanetcatalogue.com. Retrieved 2021-05-11.
    3. "Planetary Systems Composite Data". NASA Exoplanet Archive. Retrieved 16 January 2022.
    4. "About the Planetary Systems Composite Parameters Table". NASA Exoplanet Archive. 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)". www.universeguide.com. 27 April 2019. Retrieved 2022-02-20.
    6. "The Extrasolar Planet Encyclopaedia — Kepler-737 b". exoplanet.eu. Retrieved 2021-05-11.
    7. HEC HZ hpcf.upr.edu
    8. "Gaia | Description & Facts". Encyclopedia Britannica. Retrieved 2021-05-24.
    9. "Open Exoplanet Catalogue - Venus". www.openexoplanetcatalogue.com. Retrieved 16 January 2022.
    10. "Tidally locked exoplanets may be more common than previously thought". UW News. Retrieved 2021-05-18.
    11. Hammond, Mark; Lewis, Neil T. (2021-03-30). "The rotational and divergent components of atmospheric circulation on tidally locked planets". Proceedings of the National Academy of Sciences. 118 (13): e2022705118. arXiv:2102.11760. Bibcode:2021PNAS..11822705H. doi:10.1073/pnas.2022705118. ISSN 0027-8424. PMC 8020661. PMID 33753500.
    12. Sutter, Paul (2021-03-08). "Can super-rotating oceans cool off extreme exoplanets?". Space.com. Retrieved 2021-05-18.
    13. "Are tardigrades really aliens? | A World Unseen: the diversity of life". u.osu.edu. Retrieved 2021-05-11.
    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". The Astrophysical Journal. 880 (1): 64. arXiv:1804.00071. Bibcode:2019ApJ...880...64G. doi:10.3847/1538-4357/ab24be. ISSN 0004-637X. S2CID 119288494.
    15. "GJ 832c: Habitable Super-Earth or Super-Venus?". Drew Ex Machina. 2014-06-27. Retrieved 2022-05-21.
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