Epsilon Aurigae (ε Aur / ε Aurigae) is a star in the constellation Auriga. It also has the traditional names Haldus, Almaaz, or Al Anz. Epsilon Aurigae is an eclipsing binary, whose brightness varies in apparent visual magnitude between +3.0 and +3.8 with a period of about 9,890 days (~27.1 years). It is approximately 2,000 light years distant. From the Glossary of Astronomical Terms by the Harvard-Smithsonian Center for Astrophysics: Either of the two points (vernal, autumnal) on the celestial sphere where the ecliptic (which is the apparent path of the sun on the sky) intersects the celestial equator. ... This article or section does not cite its references or sources. ... Auriga (IPA: , Latin: ) is a northern constellation. ... Equatorial Coordinates Right ascension (abbrev. ... In astronomy, declination (abbrev. ... // 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, the 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, the 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. ... Animation showing how an eclipsing binary stars light intensity changes as they orbit An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ... Illustration of the use of optical wavelength interferometry to determine precise positions of stars. ... 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. ... This does not adequately cite its references or sources. ... A milliarcsecond (m, mas) , or a thoundsanth of an arcsecond. ... Distance is a numerical description of how far apart things lie. ... A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one Julian year. ... 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. ... Unsolved problems in physics: What causes anything to have mass? The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Mass is the property of a physical object that quantifies the amount of matter and energy it is equivalent to. ... In astronomy, the solar mass is a unit of mass used to express the mass of stars and larger objects such as galaxies. ... Remote Authentication Dial In User Service (RADIUS) is an AAA (authentication, authorization and accounting) protocol for applications such as network access or IP mobility. ... 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. ... Fig. ... The Kelvin scale is a thermodynamic (absolute) temperature scale where absolute zero—the lowest possible temperature where nothing could be colder and no heat energy remains in a substance—is defined as zero kelvin (0 K). ... The globular cluster M80. ... A sphere rotating around its axis. ... This article is about the astronomical object. ... 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. ... The Henry Draper Catalogue is an astronomy catalogue with astrometric and spectroscopic data about more than 225,000 stars. ... Smithsonian Astrophysical Observatory Star Catalog contain the 258,996 stars. ... The Hipparcos and Tycho Catalogues (Tycho-1) are the primary products of the European Space Agencys astrometric mission, Hipparcos. ... SIMBAD (the Set of Identifications, Measurements, and Bibliography for Astronomical Data) is a database of astronomical information about objects within the Milky Way. ... This article or section does not cite its references or sources. ... Auriga (IPA: , Latin: ) is a northern constellation. ... Animation showing how an eclipsing binary stars light intensity changes as they orbit An eclipsing binary star is a binary star in which the orbit plane of the two stars lies so nearly in the line of sight of the observer that the components undergo mutual eclipses. ... The apparent magnitude (m) of a star, planet or other heavenly body is a measure of its apparent brightness; that is, the amount of light received from the object. ... A light-year or lightyear (symbol: ly) is a unit of measurement of length, specifically the distance light travels in vacuum in one Julian year. ...

The visible component is a supergiant belonging to the spectral class A8 and is among some of the most luminous stars within 1000 parsecs of the Sun. Its diameter corresponds to about 100 solar diameters. The other (eclipsing) component is not visible. Supergiants are the most massive stars. ... 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. ... Below is a list of stars in arranged in order of increasing absolute bolometric magnitude (decreasing luminosity). ... This article is about the unit of length. ...

• The most-favored speculation is that it consists of one or two small stars with a ring of opaque dust set nearly edge-on, producing the observed eclipses of 2 years' duration.
• The alternate hypothesis is that it is immense, but of low density, and thus semi-transparent.

• This system was an early candidate for containing a black hole but the two models given above are now preferred. See [1] and [2]

The next eclipse occurs from 2009-2011, and it is hoped that the extensive observations that will likely be carried out may yield further insights into the nature of this system. Finding the star is not difficult; it is the apex of the isoceles triange formed as the 'nose' of the constellation Auriga, and is visible throughout the winter at northern latitudes, not far from brilliant, yellow Capella. A black hole is an object predicted by general relativity,[1] with a gravitational field so powerful that even electromagnetic radiation (such as light) cannot escape its pull. ...

External links

• David Darling's encyclopedia
• Epsilon Aurigae article by Dr. Jim Kaler.
• The coming eclipse of epsilon Aurigae by Professor Stencel.