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  2. Habitable zone - Wikipedia

    en.wikipedia.org/wiki/Habitable_zone

    For example, according to Kopparapu's habitable zone estimate, although the Solar System has a circumstellar habitable zone centered at 1.34 AU from the Sun, [5] a star with 0.25 times the luminosity of the Sun would have a habitable zone centered at , or 0.5, the distance from the star, corresponding to a distance of 0.67 AU. Various ...

  3. Astronomical unit - Wikipedia

    en.wikipedia.org/wiki/Astronomical_unit

    [7] [15] [16] Equivalently, by this definition, one au is "the radius of an unperturbed circular Newtonian orbit about the sun of a particle having infinitesimal mass, moving with an angular frequency of 0.017 202 098 95 radians per day "; [17] or alternatively that length for which the heliocentric gravitational constant (the product GM ...

  4. Habitability of binary star systems - Wikipedia

    en.wikipedia.org/wiki/Habitability_of_binary...

    Centauri A and B have an 11 au distance at closest approach (23 au mean), and both have stable habitable zones. [ 2 ] [ 7 ] A study of long-term orbital stability for simulated planets within the system shows that planets within approximately three au of either star may remain stable (i.e. the semi-major axis deviating by less than 5%).

  5. Planetary habitability - Wikipedia

    en.wikipedia.org/wiki/Planetary_habitability

    K-type stars may be able to support life far longer than the Sun. [26] Whether fainter late K and M class red dwarf stars are also suitable hosts for habitable planets is perhaps the most important open question in the entire field of planetary habitability given their prevalence (habitability of red dwarf systems).

  6. Habitability of K-type main-sequence star systems - Wikipedia

    en.wikipedia.org/wiki/Habitability_of_K-type...

    K-type main-sequence stars, also known as orange dwarfs, may be candidates for supporting extraterrestrial life.These stars are known as "Goldilocks stars" as they emit enough radiation in the non-UV ray spectrum [1] to provide a temperature that allows liquid water to exist on the surface of a planet; they also remain stable in the main sequence longer than the Sun by burning their hydrogen ...

  7. Galactic habitable zone - Wikipedia

    en.wikipedia.org/wiki/Galactic_habitable_zone

    In astrobiology and planetary astrophysics, the galactic habitable zone is the region of a galaxy in which life is most likely to develop. The concept of a galactic habitable zone analyzes various factors, such as metallicity (the presence of elements heavier than hydrogen and helium) and the rate and density of major catastrophes such as supernovae, and uses these to calculate which regions ...

  8. Solar radius - Wikipedia

    en.wikipedia.org/wiki/Solar_radius

    Evolution of the solar luminosity, radius and effective temperature compared to the present-day Sun. After Ribas (2009) [3] The uncrewed SOHO spacecraft was used to measure the radius of the Sun by timing transits of Mercury across the surface during 2003 and 2006. The result was a measured radius of 696,342 ± 65 kilometres (432,687 ± 40 ...

  9. Habitability of F-type main-sequence star systems - Wikipedia

    en.wikipedia.org/wiki/Habitability_of_F-type...

    KOI-4878.01 is a potentially habitable exoplanet candidate orbiting an F8-type star. It is Earth-sized, with a period of 449 days and a semi-major axis of 1.137 AU. The equilibrium temperature is 258 K (−15 °C; 5 °F), and it gets just 1.04 times the light that Earth gets from the Sun.