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Mersenne primes and perfect numbers are two deeply interlinked types of natural numbers in number theory. Mersenne primes, named after the friar Marin Mersenne, are prime numbers that can be expressed as 2 p − 1 for some positive integer p. For example, 3 is a Mersenne prime as it is a prime number and is expressible as 2 2 − 1.
A diagram of a typical nautical sextant, a tool used in celestial navigation to measure the angle between two objects viewed by means of its optical sight. Celestial navigation, also known as astronavigation, is the practice of position fixing using stars and other celestial bodies that enables a navigator to accurately determine their actual current physical position in space or on the ...
A star prime is a star number that is prime. The first few star primes (sequence A083577 in the OEIS) are 13, 37, 73, 181, 337, 433, 541, 661, 937. A superstar prime is a star prime whose prime index is also a star number. The first two such numbers are 661 and 1750255921. A reverse superstar prime is a star number whose index is a star prime ...
Stars that have magnitudes between 1.5 and 2.5 are called second-magnitude; there are some 20 stars brighter than 1.5, which are first-magnitude stars (see the list of brightest stars). For example, Sirius is magnitude −1.46, Arcturus is −0.04, Aldebaran is 0.85, Spica is 1.04, and Procyon is 0.34.
The scale does depend on cosmological parameters like the baryon and matter densities, and the number of neutrinos, so distances based on BAO are more dependent on cosmological model than those based on local measurements. Light echos can be also used as standard rulers, [27] [28] although it is challenging to correctly measure the source geometry.
The bolometric correction scale is set by the absolute magnitude of the Sun and an adopted (arbitrary) absolute bolometric magnitude for the Sun.Hence, while the absolute magnitude of the Sun in different filters is a physical and not arbitrary quantity, the absolute bolometric magnitude of the Sun is arbitrary, and so the zero-point of the bolometric correction scale that follows from it.
Stars Without Number is a science fiction role-playing game set in the year 3200. The book provides a pre-generated series of planets, but the gamemaster can also use a system of nested random tables to first create a sector in space seeded with random stars. Each star has one main planet, which the gamemaster creates, giving it two randomly ...
Older catalogues either assigned an arbitrary number to each object, or used a simple systematic naming scheme based on the constellation the star lies in, like the older Ptolemy's Almagest in Greek from 150 and Al-Sufi's Book of Fixed Stars in Arabic from 964. The variety of sky catalogues now in use means that most bright stars currently have ...