Eta Cassiopeiae (η Cas / η Cassiopeiae) is a star system 19.4 light years away from Earth, in the constellation Cassiopeia. Sometimes the traditional name Achird is used. In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Orion is a remarkable constellation, visible from most places on the globe at one time or another during the year. ... Cassiopeia can refer to: Cassiopeia (or Casseipeia), a queen of Aethiopia in Greek mythology. ... Right ascension (RA; symbol α: Greek letter alpha) is the astronomical term for one of the two coordinates of a point on the celestial sphere when using the equatorial coordinate system. ... In astronomy, declination (dec) is one of the two coordinates of the equatorial coordinate system, the other being either right ascension or hour angle. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... In astronomy, color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... In astronomy, color index is a simple numerical expression that determines the color of an object, which in the case of a star gives its temperature. ... Most stars are of almost constant luminosity. ... RS Canum Venaticorum variables are a type of variable star. ... This article does not cite its references or sources. ... Radial velocity is the velocity of an object in the direction of the line of sight. ... kilometre per second is an SI derived unit of both speed (scalar) and velocity (vector), signified by the symbol km/s or km s-1. ... The proper motion of a star is the motion of the position of the star in the sky (the change in direction in which we see it, as opposed to the radial velocity) after eliminating the improper motions of the stars, which affect their measured coordinates but are not real... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... Parallax (Greek: παραλλαγή (parallagé) = alteration) is the change of angular position of two stationary points relative to each other as seen by an observer, due to the motion of an observer. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... The distance between two points is the length of a straight line segment between them. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Stellar parallax motion The parsec (symbol pc) is a unit of length used in astronomy. ... In astronomy, absolute magnitude is the apparent magnitude, m, an object would have if it were at a standard luminosity distance away from us (in the absence of interstellar extinction!). It allows the overall brightnesses of objects to be compared without regard to distance. ... Artists impression of a binary star system consisting of a black hole, with an accretion disc around it, and a main sequence star. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... In geometry, the semi-major axis (also semimajor axis) a applies to ellipses and hyperbolas. ... In astrodynamics, under standard assumptions any orbit must be of conic section shape. ... Inclination in general is the angle between a reference plane and another plane or axis of direction. ... An orbital node is one of the two points where an inclined orbit crosses a plane of reference (e. ... This article is about several astronomical terms (apogee & perigee, aphelion & perihelion, generic equivalents based on apsis, and related but rarer terms. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... Mass is a property of a physical object that quantifies the amount of matter and energy it contains. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... In classical geometry, a radius of a circle or sphere is any line segment from its center to its boundary. ... In astronomy, the solar radius is a unit of length used to express the size of stars and larger objects such as galaxies. ... Luminosity has different meanings in several different fields of science. ... The solar luminosity, , is a unit of luminosity (power emitted in the form of photons) conventionally used by astronomers to give the luminosities of stars. ... Temperature is also the name of a song by Sean Paul. ... The kelvin (symbol: K) is the SI unit of temperature, and is one of the seven SI base units. ... In astronomy, the metallicity of an object is the proportion of its matter made up of chemical elements other than hydrogen and helium. ... Rotation of a plane, seen as the rotation of the terrain relative to the plane (exposure time 1. ... The Pleiades star cluster A star is a massive, compact body of plasma in outer space that is currently producing or has produced energy through nuclear fusion. ... A year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... The Smithsonian Astrophysical Observatory (SAO) is a research institute of the Smithsonian Institution headquartered in Cambridge, Massachusetts, where it is joined with the Harvard College Observatory (HCO) to form the Harvard-Smithsonian Center for Astrophysics (CfA). ... In astronomy, many stars are referred to simply by catalogue numbers. ... In astronomy, many stars are referred to simply by catalogue numbers. ... A star system or stellar system is a system comprised of a star or group of stars, and, perhaps, planetary systems of smaller bodies (such as planets or asteroids), in gravitational association. ... A light year, abbreviated ly, is the distance light travels in one year: roughly 9. ... Earth (often referred to as The Earth) is the third planet in the solar system in terms of distance from the Sun, and the fifth in order of size. ... Cassiopeia is a northern constellation which Greek mythology considered to represent a vain queen. ...

The primary star in the η Cassiopeiae system is a yellow dwarf (main sequence) star of spectral type G3 V, putting it in the same spectral class as our Sun, which is of spectral type G2V. It therefore resembles what our Sun might look like if we were to observe it from η Cassiopeiae. The star is of apparent magnitude 3.45. The star has a cooler and dimmer (magnitude 7.51) orange dwarf companion of spectral type K7V. The system is an RS Canum Venaticorum type variable star and its brightness varies by 0.05 magnitudes. Hertzsprung-Russell diagram The main sequence of the Hertzsprung-Russell diagram is the curve where the majority of stars are located in this diagram. ... In astronomy, stellar classification is a classification of stars based initially on photospheric temperature and its associated spectral characteristics, and subsequently refined in terms of other characteristics. ... The Sun is the star at the center of our solar system. ... // Headline text HEY!! HOW ARE YOU ALL?? Its nice of you to come read this page. ... RS Canum Venaticorum variables are a type of variable star. ... Most stars are of almost constant luminosity. ...

There are six dimmer optical components listed in the Washington Double Star Catalog. However, none of them are related to the η Cassiopeiae system and are in reality more distant stars. When two stars are so nearly in the same direction as seen from Earth that they appear to be a single star to the naked eye but may be separated by the use of telescopes, they are referred to as a double star. ... In astronomy, many stars are referred to simply by catalogue numbers. ...

In fiction

• In the Star Trek science fiction franchise, the planet Terra Nova, also known as Eta Cassiopeia III (note spelling), is located in the η Cassiopeiae system.

Star Trek collectively refers to an American science-fiction franchise spanning six unique television series (which comprise 726 episodes) and ten feature films, in addition to hundreds of novels, computer and video games, fan stories, and other works of fiction — all of which are set within the same fictional universe... A planet is generally considered to be a relatively large mass of accreted matter in orbit around a star. ... Terra Nova is the 5th episode (production #106) of the television series Star Trek: Enterprise. ...

External links

• Eta Cassiopeiae 2. SolStation. Retrieved on November 3, 2005.