PSR B1257+12 B

PSR B1257+12 B, alternatively designated PSR B1257+12 c, also named Poltergeist, is an extrasolar planet approximately 980 light-years away in the constellation of Virgo. It was the first planet ever discovered outside the Solar System, and is one of three pulsar planets known to be orbiting the pulsar PSR B1257+12.

Over four times as massive as the Earth, it circles the primary at a distance of 0.36 AU with an orbital period of approximately 66 days. Because it and PSR B1257+12 C have very similar masses and orbit close to each other, they were expected to cause measurable perturbations in each other's orbits. Detecting such perturbations confirmed that the planets were real. Accurate masses of the two planets, as well as their inclinations, were calculated from how much the planets perturb each other.

Nomenclature

The convention that arose for designating pulsars was that of using the letters PSR (Pulsating Source of Radio) followed by the pulsar's right ascension and degrees of declination. The modern convention prefixes the older numbers with a B meaning the coordinates are for the 1950.0 epoch. All new pulsars have a J indicating 2000.0 coordinates and also have declination including minutes. Pulsars that were discovered before 1993 tend to retain their B names rather than use their J names, but all pulsars have a J name that provides more precise coordinates of its location in the sky.

Poltergeist (2015 film)

Poltergeist is a 2015 American supernatural adventure horror film directed by Gil Kenan, written by David Lindsay-Abaire, and produced by Roy Lee & Sam Raimi. A remake of the 1982 film of the same name, the film stars Sam Rockwell, Rosemarie DeWitt, Jared Harris, and Jane Adams. It was released on May 22, 2015, by 20th Century Fox and Metro-Goldwyn-Mayer. The film grossed over $95 million worldwide.

Plot

Eric (Sam Rockwell) and Amy Bowen (Rosemarie DeWitt) are a married couple looking to buy a house for themselves and their three children: 16 year old eldest daughter, Kendra (Saxon Sharbino), their 9-year-old son, Griffin (Kyle Catlett), and 6-year-old youngest daughter, Madison (Kennedi Clements). Eric was recently laid off, but they are shown a house that has recently come on the market that fits their price range, so they purchase it and move in.

The first night, they hear strange noises in the walls, and Griffin finds a box of clown dolls that were left at the house. In the middle of the night, lights and electronic devices start turning on and off, as some unseen force appears to move through the home. The commotion wakes Griffin, and he goes downstairs and finds Madison talking to an unknown presence inside the television. She tells Griffin someone is coming, and he attempts to unplug the TV, causing the lights to go out of control. Madison then tells the family they are here. The following evening, Eric and Amy go to dinner with their friends, leaving the three children at home. They learn that their house was built on an old cemetery, but the bodies were moved to a better neighborhood.

Poltergeist (disambiguation)

Poltergeist may refer to:

Tangent

In geometry, the tangent line (or simply tangent) to a plane curve at a given point is the straight line that "just touches" the curve at that point. Leibniz defined it as the line through a pair of infinitely close points on the curve. More precisely, a straight line is said to be a tangent of a curve y = f (x) at a point x = c on the curve if the line passes through the point (c, f (c)) on the curve and has slope f '(c) where f ' is the derivative of f. A similar definition applies to space curves and curves in n-dimensional Euclidean space.

As it passes through the point where the tangent line and the curve meet, called the point of tangency, the tangent line is "going in the same direction" as the curve, and is thus the best straight-line approximation to the curve at that point.

Similarly, the tangent plane to a surface at a given point is the plane that "just touches" the surface at that point. The concept of a tangent is one of the most fundamental notions in differential geometry and has been extensively generalized; see Tangent space.

Tangent (disambiguation)

A tangent, in geometry, is a straight line through a point on a curve that has the same direction at that point as the curve.

Tangent may also refer to:

Mathematics

Music

Trigonometric functions

In mathematics, the trigonometric functions (also called the circular functions) are functions of an angle. They relate the angles of a triangle to the lengths of its sides. Trigonometric functions are important in the study of triangles and modeling periodic phenomena, among many other applications.

The most familiar trigonometric functions are the sine, cosine, and tangent. In the context of the standard unit circle (a circle with radius 1 unit), where a triangle is formed by a ray originating at the origin and making some angle with the x-axis, the sine of the angle gives the length of the y-component (the opposite to the angle or the rise) of the triangle, the cosine gives the length of the x-component (the adjacent of the angle or the run), and the tangent function gives the slope (y-component divided by the x-component). More precise definitions are detailed below. Trigonometric functions are commonly defined as ratios of two sides of a right triangle containing the angle, and can equivalently be defined as the lengths of various line segments from a unit circle. More modern definitions express them as infinite series or as solutions of certain differential equations, allowing their extension to arbitrary positive and negative values and even to complex numbers.