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26) Republic Day 2021: Parade timing security arrangements traffic limitations to Delhi Metro expert services - All you need to know

India Republic Day -- Republic Day 2021 Parade Schedule Chief Guest Security Agreements: The parade normally views thousands of people and foreign dignitaries invited to see the parade. Still the number of guests and people has been restricted due to the coronavirus pandemic this time. Republic Morning 2021 Parade Timings Primary Guest Delhi Metro Companies: India will celebrate its 72nd Republic Day on January 26. This day is definitely marked to celebrate the day on which the Constitution regarding India came into being in 1950. On this day the Republic Day parade takes place to show the military might and also the rich cultural heritage from the country. The parade generally sees thousands of people and overseas dignitaries invited to see the parade. However the number of guests in addition to attendees has been restricted because of the coronavirus pandemic this time. This current year there will be no chief invitees or foreign dignitaries on Republic Day. The number of vistors ...
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Exoplanet

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An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917, but was not recognized as such. The first confirmation of detection occurred in 1992. This was followed by the confirmation of a different planet, originally detected in 1988. As of 1 November 2020, there are 4,370 confirmed exoplanets in 3,230 systems, with 715 systems having more than one planet. There are many methods of detecting exoplanets. Transit photometry and Doppler spectroscopy have found the most, but these methods suffer from a clear observational bias favoring the detection of planets near the star; thus, 85% of the exoplanets detected are inside the tidal locking zone. In several cases, multiple planets have been observed around a star. About 1 in 5 Sun-like starsa have an "Earth-sized"b planet in the habitable zone.c Assuming there are 200 billion stars in the Milky Way,d it can be hypothesized that there are 11 billion pote...
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Definition

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IAU edit The official definition of the term planet used by the International Astronomical Union (IAU) only covers the Solar System and thus does not apply to exoplanets. The only defining statement issued by the IAU that pertains to exoplanets is a working definition issued in 2001 and modified in 2003. An exoplanet is defined by the following criteria: Objects with true masses below the limiting mass for thermonuclear fusion of deuterium (currently calculated to be 13 Jupiter masses for objects of solar metallicity) that orbit stars or stellar remnants are "planets" (no matter how they formed). The minimum mass/size required for an extrasolar object to be considered a planet should be the same as that used in the Solar System. Substellar objects with true masses above the limiting mass for thermonuclear fusion of deuterium are "brown dwarfs", no matter how they formed or where they are located. Free-floating objects in young star clusters with masses below th...
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Nomenclature

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The convention for designating exoplanets is an extension of the system used for designating multiple-star systems as adopted by the International Astronomical Union (IAU). For exoplanets orbiting a single star, the IAU designation is formed by taking the designated or proper name of its parent star, and adding a lower case letter. Letters are given in order of each planet's discovery around the parent star, so that the first planet discovered in a system is designated "b" (the parent star is considered to be "a") and later planets are given subsequent letters. If several planets in the same system are discovered at the same time, the closest one to the star gets the next letter, followed by the other planets in order of orbital size. A provisional IAU-sanctioned standard exists to accommodate the designation of circumbinary planets. A limited number of exoplanets have IAU-sanctioned proper names. Other naming systems exist.
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History of detection

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For centuries scientists, philosophers, and science fiction writers suspected that extrasolar planets existed, but there was no way of knowing whether they existed, how common they were, or how similar they might be to the planets of the Solar System. Various detection claims made in the nineteenth century were rejected by astronomers. The first evidence of a possible exoplanet, orbiting Van Maanen 2, was noted in 1917, but was not recognized as such. The astronomer Walter Sydney Adams, who later became director of the Mount Wilson Observatory, produced a spectrum of the star using Mount Wilson's 60-inch telescope. He interpreted the spectrum to be of an F-type main-sequence star, but it is now thought that such a spectrum could be caused by the residue of a nearby exoplanet that had been pulverized into dust by the gravity of the star, the resulting dust then falling onto the star. The first suspected scientific detection of an exoplanet occurred in 1988. Shortly afterwards, the f...
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Methodology

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About 97% of all the confirmed exoplanets have been discovered by indirect techniques of detection, mainly by radial velocity measurements and transit monitoring techniques. Recently the techniques of singular optics have been applied in the search for exoplanets.
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Formation and evolution

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Planets may form within a few to tens (or more) of millions of years of their star forming. The planets of the Solar System can only be observed in their current state, but observations of different planetary systems of varying ages allows us to observe planets at different stages of evolution. Available observations range from young proto-planetary disks where planets are still forming to planetary systems of over 10 Gyr old. When planets form in a gaseous protoplanetary disk, they accrete hydrogen/helium envelopes. These envelopes cool and contract over time and, depending on the mass of the planet, some or all of the hydrogen/helium is eventually lost to space. This means that even terrestrial planets may start off with large radii if they form early enough. An example is Kepler-51b which has only about twice the mass of Earth but is almost the size of Saturn which is a hundred times the mass of Earth. Kepler-51b is quite young at a few hundred million years old.
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