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Habitability Of K-type Main-sequence Star Systems
K-type main-sequence stars may be the candidates for supporting extraterrestrial life. These stars are known as "Goldilocks stars" as they emit enough radiation in the non- UV ray spectrum 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 slower, allowing more time for life to form on a planet around a K-type main-sequence star. The planet's habitable zone, ranging from 0.1–0.4 to 0.3–1.3 astronomical units (AU), depending on the size of the star, is often far enough from the star so as not to be tidally locked to the star, and to have a sufficiently low solar flare activity not to be lethal to life. In comparison, red dwarf stars have too much solar activity and quickly tidally lock the planets in their habitable zones, making them less suitable for life. The odds of complex life arising may be better on planets around K-type main-sequence stars than ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
K-type Main-sequence Star
A K-type main-sequence star, also referred to as a K-type dwarf or an orange dwarf, is a main-sequence (hydrogen-burning) star of spectral type K and luminosity class V. These stars are intermediate in size between red M-type main-sequence stars ("red dwarfs") and yellow/white G-type main-sequence stars. They have masses between 0.6 and 0.9 times the mass of the Sun and surface temperatures between 3,900 and 5,300 K. These stars are of particular interest in the search for extraterrestrial life due to their stability and long lifespan. Well-known examples include Alpha Centauri B (K1 V) and Epsilon Indi (K5 V). Spectral standard stars The revised Yerkes Atlas system (Johnson & Morgan 1953) listed 12 K-type dwarf spectral standard stars, however not all of these have survived to this day as standards. The "anchor points" of the MK classification system among the K-type main-sequence dwarf stars, i.e. those standard stars that have remain unchanged over the years, are: *Sigma D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 40307
HD 40307 is an orange ( K-type) main-sequence star located approximately 42 light-years away in the constellation of Pictor (the Easel), taking its primary name from its Henry Draper Catalogue designation. It is calculated to be slightly less massive than the Sun. The star has six known planets, three discovered in 2008 and three more in 2012. One of them, HD 40307 g, is a potential super-Earth in the habitable zone, with an orbital period of about 200 days. This object might be capable of supporting liquid water on its surface, although much more information must be acquired before its habitability can be assessed. No stellar companions to HD 40307 were detected as in 2018. History and nomenclature HD 40307 was observed during or before 1900 as part of the Cape Photographic Durchmusterung. The designation ''HD 40307'' is from the Henry Draper Catalogue, which is based on spectral classifications made between 1911 and 1915 by Annie Jump Cannon and her co-workers, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Habitability
Planetary habitability is the measure of a planet's or a natural satellite's potential to develop and maintain environments hospitable to life. Life may be generated directly on a planet or satellite endogenously or be transferred to it from another body, through a hypothetical process known as panspermia. Environments do not need to contain life to be considered habitable nor are accepted habitable zones (HZ) the only areas in which life might arise. As the existence of life beyond Earth is unknown, planetary habitability is largely an extrapolation of conditions on Earth and the characteristics of the Sun and Solar System which appear favorable to life's flourishing. Of particular interest are those factors that have sustained complex, multicellular organisms on Earth and not just simpler, unicellular creatures. Research and theory in this regard is a component of a number of natural sciences, such as astronomy, planetary science and the emerging discipline of astrobio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitability Of Yellow Dwarf Systems
Habitability of yellow dwarf systems defines the suitability for life of exoplanets belonging to yellow dwarf stars. These systems are the object of study among the scientific community because they are considered the most suitable for harboring living organisms, together with those belonging to K-type stars.Perryman, 2011, p. 285 Yellow dwarfs comprise the G-type stars of the main sequence, with masses between 0.9 and 1.1 M☉ and surface temperatures between 5000 and 6000 K, like the Sun.''Stellar classification''. '' British Encyclopedia''. Retrieved october 8th, 2015. They are the third most common in the Milky Way Galaxy and the only ones in which the habitable zone coincides completely with the ultraviolet habitable zone. Since the habitable zone is farther away in more massive and luminous stars, the separation between the main star and the inner edge of this region is greater in yellow dwarfs than in red and orange dwarfs.Niels Bohr Institute. (2015Planets in the habi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitability Of Red Dwarf Systems
The habitability of red dwarf systems is presumed to be determined by a large number of factors from a variety of sources. Modern evidence indicates that planets in red dwarf systems are unlikely to be habitable, due to their low stellar flux, high probability of tidal locking, small circumstellar habitable zones and the high stellar variation experienced by planets of red dwarf stars, impeding their planetary habitability. However, the ubiquity and longevity of red dwarfs are factors which could provide ample opportunity for any possibility of habitability to be realized. As red dwarf stars are by far the most common type of star in the universe, astronomers study how each of the many factors, and the interactions among them, could affect their habitability to learn more about the frequency and most likely locations of extraterrestrial life and intelligence. A major impediment to life developing in these systems is the intense tidal heating caused by the proximity of planets t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Habitability Of Neutron Star Systems
The habitability of neutron star systems means assessing and surveying whether life is possible on planets and moons orbiting a neutron star. A habitable planet orbiting a neutron star must be between one and 10 times the mass of the Earth. If the planet were lighter, its atmosphere would be lost. Its atmosphere must also be thick enough to convert the intense X-ray radiation emanating from the parent star into heat on its surface. Then it could have the temperature suitable for life. A magnetic field strong enough — the magnetosphere — would protect the planet from the strong solar winds. This could preserve the planet's atmosphere for several billion years. Such a planet could have liquid water on its surface. A Dutch research team published an article on the subject in the journal ''Astronomy & Astrophysics'' in December 2017. See also * Habitability of red dwarf systems * Habitability of K-type main-sequence star systems * Habitability of natural satellites * ''Drago ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astrobiology
Astrobiology, and the related field of exobiology, is an interdisciplinary scientific field that studies the origins, early evolution, distribution, and future of life in the universe. Astrobiology is the multidisciplinary field that investigates the deterministic conditions and contingent events with which life arises, distributes, and evolves in the universe. Astrobiology makes use of molecular biology, biophysics, biochemistry, chemistry, astronomy, physical cosmology, exoplanetology, geology, paleontology, and ichnology to investigate the possibility of life on other worlds and help recognize biospheres that might be different from that on Earth. The origin and early evolution of life is an inseparable part of the discipline of astrobiology. Astrobiology concerns itself with interpretation of existing scientific data, and although speculation is entertained to give context, astrobiology concerns itself primarily with hypotheses that fit firmly into existing scientific ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 85512 B
HD 85512 b is an exoplanet orbiting HD 85512, a K-type main-sequence star approximately 37 light-years from Earth in the constellation of Vela. Due to its mass of at least 3.6 times the mass of Earth, HD 85512 b is classified as a rocky Earth-size exoplanet (< 5M🜨) and is one of the smallest exoplanets discovered to be just outside the inner edge of the . HD 85512 b, along with , was once considered to be one of the best candidates for habitability in 2011. Physical characteristics
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Kepler-442
Kepler-442 is a K-type main-sequence star approximately 1,206 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 notable stars of Kepler-438 and Kepler-440, it was announced that the star has an extrasolar planet (a super-Earth) orbiting within the habitable zone, named Kepler-442b. Nomenclature and history Prior to Kepler observation, Kepler-442 had the 2MASS catalogue number 2MASS J19012797+3916482. In the Kepler Input Catalog it has the designation of KIC 4138008, and when it was found to have transiting planet candidates it was given the Kepler object of interest number of KOI-4742. Planetary candidates were detected around the star by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit method that Kepler uses invo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kepler-62
Kepler-62 is a K-type main sequence star cooler and smaller than the Sun, located roughly 990 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. Nomenclature and history Prior to Kepler observation, Kepler-62 had the 2MASS catalogue number 2MASS J18525105+4520595. In the Kepler Input Catalog it has the designation of KIC 9002278, and when it was found to have transiting planet candidates it was given the Kepler object of interest number of KOI-701. Planetary candidates were detected around the star by NASA's Kepler Mission, a mission tasked with discovering planets in transit around their stars. The transit m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kepler Space Telescope
The Kepler space telescope is a disused space telescope launched by NASA in 2009 to discover Earth-sized planets orbiting other stars. Named after astronomer Johannes Kepler, the spacecraft was launched into an Earth-trailing heliocentric orbit. The principal investigator was William J. Borucki. After nine and a half years of operation, the telescope's reaction control system fuel was depleted, and NASA announced its retirement on October 30, 2018. Designed to survey a portion of Earth's region of the Milky Way to discover Earth-size exoplanets in or near habitable zones and estimate how many of the billions of stars in the Milky Way have such planets, Kepler's sole scientific instrument is a photometer that continually monitored the brightness of approximately 150,000 main sequence stars in a fixed field of view. These data were transmitted to Earth, then analyzed to detect periodic dimming caused by exoplanets that cross in front of their host star. Only planets whose ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HD 40307 G
HD 40307 g is an exoplanet candidate suspected to be orbiting in the habitable zone of HD 40307. It is located 42 light-years away in the direction of the southern constellation Pictor. The planet was discovered by the radial velocity method, using the European Southern Observatory's HARPS apparatus by a team of astronomers led by Mikko Tuomi at the University of Hertfordshire and Guillem Anglada-Escude of the University of Göttingen, Germany. The existence of the planet was disputed in 2015, as more Doppler spectroscopy data has become available. Planetary characteristics The codiscoverer Hugh Jones, of the University of Hertfordshire in England, surmised: "The longer orbit of the new planet means that its climate and atmosphere may be just right to support life." However, another astronomer, Rory Barnes of the University of Washington, had already studied the orbits of the planets b, c, and d. First, Barnes had presumed b to take on too much tidal heating for it to be terre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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