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NASA Kepler Discovers New Potentially Habitable Exoplanets

posted Apr 18, 2013, 11:00 AM by Abel Mendez Torres   [ updated Apr 19, 2013, 3:08 AM ]
Two new exoplanets discovered by NASA Kepler, Kepler-62e and Kepler-62f, were added to the Habitable Exoplanets Catalog. The two planets are part of a planetary systems of five planets around a star smaller than the Sun 1,200 light years away from Earth. Both are considered potentially habitable because they have a size not much larger than Earth and orbit within the habitable zone of their parent star. Kepler-62e is now the most Earth-like exoplanet discovered so far based on the similarity to some of its properties to Earth. However, the actual habitability of Kepler-62e and Kepler-62f depends on conditions that we can not measure yet. Another interesting planet, Kepler-69c, was also announced today but was not included in the catalog because it barely matches our habitability criteria.

Check the original NASA Press Release for details.


Figure 1. Current potentially habitable exoplanets showing the new Kepler-62e and Kepler-62f. Kepler-62e is now the best candidate for an Earth-like planet based on measured parameters. However, the actual potential for life of any of these worlds depends on their atmospheric properties which are unknown at this time.


Figure 2. Current potentially habitable exoplanets showing the new additions, Kepler-62e and Kepler-62f.


Figure 3. Artistic representations of Kepler-62e and Kepler-62f compared with Earth. Both are shown with a similar terrestrial atmosphere thus making Kepler-62e slightly hotter than Earth and Kepler-62f a cold but still habitable world. Another possibility is that both have dense atmospheres. In that case the temperatures of Kepler-62f might be more suitable for life than on Kepler-62e.


Figure 4. Comparison of the orbit and size of the exoplanets of Kepler-62 with the terrestrial planets of our Solar Systems. The darker green shaded area corresponds to the 'conservative habitable zone' while its lighter borders to its 'optimistic habitable zone' extension. Planet sizes and orbits are not to scale between them.

Table 1: Planetary properties of the planets around the K2V star Kepler-62. Kepler-62e and Kepler-62f are potentially habitable and were added to the Habitable Exoplanets Catalog. This table also includes some estimated values that are not part of the original observations. They are described in the table notes below.

Table Notes:
    Planet Type - according to the PHL's Classification of Exoplanets.
    Mass was estimated for comparison purposes only using a mass-radius relationship for rocky planets.
    Equilibrium temperature was estimated assuming a bond albedo of 0.3.
    Surface temperature was estimated assuming an Earth-like atmosphere.
    The habitable zone distance (HZD) is a measure of the location of the planet with respect to the HZ. Planets with HZD values between -1 and +1. are within the HZ.
    This table uses the new revised Earth Similarity Index (ESI) which only considers the observed parameters size of the planet and stellar flux.
 
Table 2: Planetary properties of the terrestrial planets of the Solar System to be used for comparison with those of the planets of Kepler-62. See Table 1.