21. Eclipsing Binary Stars (Article) ECLIPSING binary stars. A Simple Model for Computing Light Curves. INTRODUCTION.Eclipsing binary stars are just one several types of variable stars. http://www.isc.tamu.edu/~astro/ebstar/ebstar.html

This web page has moved to another site but this page will remain active for a while longer without updates. Your web browser will move to the new site in 10 seconds. ECLIPSING BINARY STARS A Simple Model for Computing Light Curves Dan Bruton astro@tamu.edu Last updated on December 19, 1995 INTRODUCTION Eclipsing binary stars are just one several types of variable stars. These stars appear as a single point of light to an observer, but based on its brightness variation and spectroscopic observations we can say for certain that the single point of light is actually two stars in close orbit around one another. The variations in light intensity from eclipsing binary stars is caused by one star passing in front of the other relative to an observer. If we assume that the stars are spherical and that they have circular orbits, then we can easily approximate how the light varies as a function of time for eclipsing binary stars. These calculations can be performed in a relatively short computer program. THE ORBIT AND STAR PARAMETERS A brightness versus time plot for a variable star is know as light curve . For close binary systems, time is usually expressed as

22. Binary Stars binary stars By Don Ware. Looking through a telescope at the much massdo the stars have? binary stars can be of two fundamental types http://www.astronomical.org/astbook/binary.html

Binary Stars By Don Ware Looking through a telescope at the stars there is very little information we can gain from them. To be sure, we know what color they are and we can see that some are more luminous than others. If we use a spectrograph we can tell what elements they are made up from. From these facts alone, it is difficult to tell just how much mass they contain. By looking at pairs of stars that orbit one another we can try to answer the question, how much mass do the stars have? Binary stars can be of two fundamental types: Visual Binaries Optical Doubles Alberio (Visual Binary) Visual Binaries are stars that are clearly gravitational associated with one another. They orbit each other around a common center called the barycenter . Visual binaries can be seen optically through a telescope. Only a small portion of binary stars are visual binaries. In order to see a visual binary, the stars must be separated by fairly wide distances, and the orbital periods are usually very long. Optical Doubles are stars that appear to lie close together, but in fact do not, they only appear to us from our earthly observation to be close together. One of the stars in the pair is actually behind the first star and very far away. The stars of an optical double are not gravitationally bound.

23. Binary Stars binary stars Planet's revolve around stars because of gravity. binary starsobey Kepler's Laws of Planetary Motion, of which there are three. http://zebu.uoregon.edu/~js/ast222/lectures/lec05.html

Binary Stars Planet's revolve around stars because of gravity. However, gravity is not restricted to between large and small bodies, stars can revolve around stars as well. In fact, 85% of the stars in the Milky Way galaxy are not single stars, like the Sun, but multiple star systems, binaries or triplets. If two stars orbit each other at large separations, they evolve independently and are called a wide pair . If the two stars are close enough to transfer matter by tidal forces, then they are called a close or contact pair Binary stars obey Kepler's Laws of Planetary Motion, of which there are three. 1st law (law of elliptic orbits): Each star or planet moves in an elliptical orbit with the center of mass at one focus. Ellipses that are highly flattened are called highly eccentric. Ellipses that are close to a circle have low eccentricity. 2nd law (law of equal areas): a line between one star and the other (called the radius vector) sweeps out equal areas in equal times This law means that objects travel fastest at the low point of their orbits, and travel slowest at the high point of their orbits. 3rd law (law of harmonics): The square of a star or planet's orbital period is proportional to its mean distance from the center of mass cubed It is this last law that allows us to determine the mass of the binary star system (note only the sum of the two masses).

24. IAU COMMISSION 42 HOMEPAGE Organization based in Hungary that studies binary stars. http://www.konkoly.hu:80/IAUC42/

INTERNATIONAL ASTRONOMICAL UNION COMMISSION 42. CLOSE BINARY STARS (ETOILES BINARIES SERREES) WWW Services Welcome to the IAU Commission 42 World Wide Web homepage. C42 WWW Services General information Meetings Networks - Organizations - Databases Announcements ... Information Bulletin on Variable Stars IAU WWW Services International Astronomical Union homepage IAU Division V. homepage IAU Commission 27 homepage

25. X-ray Binary Stars - Introduction Xray binary stars. What is a Binary Star System? X-ray Binaries. A special classof binary stars is the X-ray binaries, so-called because they emit X-rays. http://imagine.gsfc.nasa.gov/docs/science/know_l1/binary_stars.html

Imagine Home Science Current Page Additional Links "Quiz Me!" about this topic! Cool Fact about this topic! Try This! FAQs on Binary Star Systems ... Give Me additional resources! Related Topics White Dwarfs Neutron Stars Black Holes For Educators Show me related lesson plans Animation of an X-ray Binary System X-ray Binary Stars What is a Binary Star System? Binary star systems contain two stars that orbit around their common center of mass . Many of the stars in our Galaxy are part of a binary system X-ray Binaries A special class of binary stars is the X-ray binaries, so-called because they emit X-rays . X-ray binaries are made up of a normal star and a collapsed star (a white dwarf neutron star , or black hole ). These pairs of stars produce X-rays if the stars are close enough together that material is pulled off the normal star by the gravity of the dense, collapsed star. The X-rays come from the area around the collapsed star where the material that is falling toward it is heated to very high temperatures (over a million degrees!). Show Me a Movie about X-ray Binaries!

26. X-ray Binary Stars Xray binary stars. X-ray Binaries (in yellow) near the Galactic Center.If your eyes could see X-rays rather than optical light, you http://imagine.gsfc.nasa.gov/docs/science/know_l2/binaries.html

Imagine Home Science Advanced Science Current Page Additional Links "Quiz Me!" about this topic! Cool Fact about this topic! FAQs on Binary Star Systems. Introductory Level Article on this topic. ... Give Me additional resources! For Educators Show me related lesson plans X-ray Binary Stars X-ray Binaries (in yellow) near the Galactic Center If your eyes could see X-rays rather than optical light , you would see a very different and unusual sight when you looked up at the sky. You would be overwhelmed by a few hundred very bright stars , mostly concentrated towards the center of our Galaxy . Most of these stars would in fact be X-ray binaries, where a black hole or neutron star is devouring material from its companion star. A basic quest of science is to test the laws of physics under all conditions. Unexpected discoveries can lead to breakthroughs in our understanding of the laws of nature. X-ray observations of neutron stars and black holes provide a unique probe into how the Universe operates under extreme physical conditions. Mass exchange in Binary Systems Binaries that Pulse and Flash Determining Orbits and Masses Home ... Show me a printable version of this page.

27. APOD Index - Stars: Binary Stars Astronomy Picture of the Day Index Stars binary stars. Editor's choices forthe most educational Astronomy Pictures of the Day about binary stars http://antwrp.gsfc.nasa.gov/apod/binary_stars.html

Astronomy Picture of the Day Index - Stars: Binary Stars Today's APOD Title Search Text Search Editor's choices for the most educational Astronomy Pictures of the Day about binary stars: APOD: 1999 December 19 - Accretion Disk Binary System Explanation: Our Sun is unusual in that it is alone - most stars occur in multiple or binary systems . In a binary system, the higher mass star will evolve faster and will eventually become a compact object - either a white dwarf star, a neutron star , or black hole . When the lower mass star later evolves into an expansion phase, it may be so close to the compact star that its outer atmosphere actually falls onto the compact star. Such is the case diagrammed above. Here gas from a blue giant star is shown being stripped away into an accretion disk around its compact binary companion. Gas in the accretion disk swirls around, heats up, and eventually falls onto the compact star. Extreme conditions frequently occur on the surface of the compact star as gas falls in, many times causing detectable X-rays gamma-rays , or even cataclysmic novae explosions. Studying the extreme conditions in these systems tells us about the inner properties of ordinary matter around us.

28. APOD: February 19, 1997 - Mizar Binary Star Group, USNO, NRL. Explanation Mizar (sounds like My Czar ) is abinary star. In fact, most stars are binary stars. In a binary http://antwrp.gsfc.nasa.gov/apod/ap970219.html

Astronomy Picture of the Day Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. February 19, 1997 Mizar Binary Star Credit: J. Benson et al., NPOI Group USNO NRL Explanation Mizar (sounds like "My Czar") is a binary star. In fact, most stars are binary stars . In a binary star system , each star of the pair follows an elliptical orbital path. Mutual gravity causes the stellar companions to glide around their orbits as if tied to the ends of an elastic string passing through a balance point between them . The balance point is the system's "center of mass". Also known as zeta Ursae Majoris Mizar is the middle star in the handle of the Big Dipper and at a distance of 88 light years, was the first binary star system to be imaged telescopically . Spectroscopic observations of the Mizar system show periodic doppler shifts , revealing that both stars, Mizar A and Mizar B, are themselves binary stars! But, the companions are too close to be directly observed as separate stars, even by

29. Binary Stars binary stars. Looking through a telescope at the stars there is very little informationwe can gain from them. binary stars can be of two fundamental types http://physics.hallym.ac.kr/education/Peoria/binary.html

Origin Binary Stars Looking through a telescope at the stars there is very little information we can gain from them. To be sure, we know what color they are and we can see that some are more luminous than others. If we use a spectrograph we can tell what elements they are made up from. From these facts alone, it is difficult to tell just how much mass they contain. By looking at pairs of stars that orbit one another we can try to answer the question, how much mass do the stars have? Binary stars can be of two fundamental types: Visual Binaries Optical Doubles Alberio (Visual Binary) Visual Binaries are stars that are clearly gravitational associated with one another. They orbit each other around a common center called the barycenter . Visual binaries can be seen optically through a telescope. Only a small portion of binary stars are visual binaries. In order to see a visual binary, the stars must be separated by fairly wide distances, and the orbital periods are usually very long. Optical Doubles are stars that appear to lie close together, but in fact do not, they only appear to us from our earthly observation to be close together. One of the stars in the pair is actually behind the first star and very far away. The stars of an optical double are not gravitationally bound. William Herschel began looking for optical doubles in 1782 with the hope that he would find a measurable parallax, by comparing a close star to the more distant star in an optical double.

30. IAU Symposium 200 : The Formation Of Binary Stars : Potsdam April 10-15 2000 The Formation of binary stars. 200 The Formation of binary stars was heldfrom April 10 to 15, 2000 in Potsdam (Germany), organized by the AIP. http://www.aip.de/IAU200/

IAU Symposium 200 The Formation of Binary Stars Potsdam, Germany April 10-15 2000 The IAU Symposium no. 200 "The Formation of Binary Stars" was held from April 10 to 15, 2000 in Potsdam (Germany), organized by the AIP First announcement Final scientific programme The conference poster ... The list of posters Important dates: Deadline for registration, abstracts, and application for financial support: Wed, Dec 15th, 1999 Submission of poster papers: Sun, Feb 20th, 2000 Symposium takes place: Mon, Apr 10th - Sat, Apr 15th, 2000 Deadline for submission of papers: Wed, Jun 14th, 2000 Deadline for hotel registrations with guaranteed room rates: Thu, 10th Feb, 2000 Scientific organising committee: Chairpersons: H. Zinnecker, co-chair R. Mathieu, co-chair Members: P. Artymowicz A. Boss J. Bouvier C. Clarke A. Dutrey A. Ghez P. Kroupa C. Leinert S. Miyama B. Reipurth M. Simon A. Tokovinin A. Whitworth Local contact information Hans Zinnecker, SOC co-chair Mark McCaughrean, LOC member Christiane Rein, secretary Phone: +49 (0)331 7499 347 Phone: +49 (0)331 7499 525 Phone +49 (0)331 7499 382 Fax: +49 (0)331 7499 267 E-mail: hzinnecker@aip.de

31. Detecting Other Worlds: Timing Eclipsing Binary Stars Or The 'Do-Si-Do' Method In my last article I discussed eclipsing binary stars; a configuration of two (generallyclose) stars that happen to orbit each other along our line of sight http://www.space.com/searchforlife/seti_doyle_worlds_011011.html

SEARCH: advertisement Timing Eclipsing Binary Stars or The 'Do-Si-Do' Method By Laurance R. Doyle SETI Institute posted: 07:00 am ET 11 October 2001 In my last article I discussed eclipsing binary stars; a configuration of two (generally close) stars that happen to orbit each other along our line of sight, thereby eclipsing each other every orbital period. The most successful way of finding planets to date—the radial velocity or "wobble" method—requires single stars since it detects the very slight offset motion of the star caused by the giant planet orbiting it. As discussed in my last article, the photometric transit method can be used to detect planets that cross two stars (the planet orbits both stars). These transits are more complex since they involve two stars orbiting each other while the planet crosses in front. SETI THURSDAY Visit SPACE.com to explore a new SETI feature each Thursday. >>Go to SETI Thursday archive page Images These Chandra images provide the first complete census of compact binary stars in the core of the globular cluster known as 47 Tucanae. Related SPACE.com STORIES

32. The Double Star Library Workshop Spectroscopically and Spatially Resolving the Componentsof Close binary stars, Dubrovnik, Croatia; 2024 October 2003. http://ad.usno.navy.mil/wds/dsl.html

Double Star Library Homepage Commission 26 ... Editor Welcome to the D OUBLE S TAR L IBRARY Recent Changes: 2003 Mar: Information Circular #149 added 2003 Jan: Fourth Interferometric Catalog updated 2003 Jan: Sixth Orbit Catalog updated Jump to: Purpose of the Library IAU Commission 26 Meeting Anouncements Bibliography ... Feedback IAU Commission 26: Binary and Multiple Stars The report of the Commission 26 business meeting held during the Manchester IAU General Assembly (August 2000) may be found in Information Circular #142. Commission 26 Officers Commission 26 Members and Other Binary Star Astronomers Information Circulars Introduction and older circulars 2002 Triennial Report also (postscript version) Circular No. 142 (Oct 2000) also (postscript version) Circular No. 143 (Feb 2001) also (postscript version) Circular No. 144 (Jun 2001) also (postscript version) Circular No. 145 (Oct 2001) also (postscript version) Circular No. 146 (Feb 2002) also (postscript version) Circular No. 147 (Jun 2002) also (postscript version) Circular No. 148

33. Sixth Orbit Catalog Sixth Catalog of Orbits of Visual binary stars. William I. Hartkopf Brian D.Mason US Naval Observatory, Washington, DC (last update 15 January 2003). http://ad.usno.navy.mil/wds/orb6.html

Sixth Catalog of Orbits of Visual Binary Stars U.S. Naval Observatory, Washington, DC (last update: 15 January 2003) Fifth Catalog of Orbits of Visual Binary Stars . That catalog, containing orbits published through 1 January 2001, is one of four USNO double star catalogs recently written to CD-ROM. Copies of this CD-ROM are available upon request . Although still available on the web as well, the Fifth Catalog has been supplanted by the Sixth Catalog , so will no longer be updated. The Sixth Catalog presently includes 1,757 orbits of 1,692 systems (from a "master file" currently containing 5,025 orbits). All orbits have been graded on a 1 - 5 scale, as in earlier catalogs; the grading scheme has been modified, however, as described below. Ephemerides are included for all orbits, as are plots including all associated data in the current Washington Double Star database. Contents: Introduction Orbit grading method Description of the catalog Catalog statistics ... Calibration Candidates Your comments regarding either style or substance are welcome. Please inform the authors ( dsl@ad.usno.navy.mil ) of any errors you run across in the catalog, as well as missing orbits, etc. We would also welcome notification (and/or copies) of any newly published elements.

34. BINARY STARS English Version. Introduction. Observational Parameters. Chronometric Micrometer.Angular micrometer. Measurements New ! article about elemental statistics. http://www.geocities.com/CapeCanaveral/Runway/8879/englishindex.html

English Version Introduction Observational Parameters Chronometric Micrometer Angular micrometer Measurements New ! article about elemental statistics Bibliography and Links Photographs Software Download Software EFEBIN ( Bajar EFEBIN ) New !!! New version 2002 !!!, Now available EFEBIN v.2002 in english version !!!. Please, write your criticisms and suggestions to this web site, or solicit EFEBIN free , to the following address: aerusso@yahoo.com Mr. Alejandro Eduardo Russo) and I will be glad to respond Thanks for visit this page ! BACK ( Volver )

35. BINARY STARS The binary stars”, by Robert G. Aitken (1964). “Some Bright Visual BinaryStars”, by Jean Meeus, Sky and Telescope, January and February 1971. http://www.geocities.com/CapeCanaveral/Runway/8879/englishbibliography.html

English Version BIBLIOGRAPHY AND LINKS: books magazine web link Books: * "The Binary Stars”, by Robert G. Aitken (1964). * "The Double Star Observer's Handbook”, by Ronald C. Tanguay (1998). * “Observing Binary and Double Stars”, by Bob Argyle, Webb Society, 2002. * "Observación de estrellas dobles por aficionados”, by José Luis Comellas, Agrupación Astronómica Albireo ( July 1983 ). ( in spanish ) * “Astronomical Formulae for calculators”, by Jean Meeus ( 1985 ). * "Astronomical Algorithms", second edition, by Jean Meeus ( 2000 ). * "Medidas Micrométricas de Estrelas Duplas em 1959-1960”, by Freitas Mourau ( 1960 ). ( in portuguese ) * “Index Catalogue of Visual Double Stars, 1961.0”, by Hamilton M. Jeffers and Willem H. Van den Bos, with Frances M. Greeby ( I.D.S. ). Mount Hamilton, California. Publications of Lick Observatory ( 1963 ). * “The Astronomical Almanac, 2001”, by U.S.N.O. . * “Astronomie Générale” ( 1952-1953, Paris, pag. 42 ), by Danjon A. ( in french ) * “Fourth Catalog of Orbits of Visual Binary Stars”, by Charles E. Worley and Wulff D. Heintz, U.S.N.O. (1983).

36. Binary Stars Simple explanation of binary stars in the framework of the historyof the Universe. Physical Environment binary stars. http://www.historyoftheuniverse.com/binaries.html

Basic Information Further Information Other Hotu Pages Questions, Answers, Comments Physical Environment ... Later This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. More than half of all stars have one or more close companion stars, to which it is tied by gravity . When there are only two stars in orbit around each other they are called a binary star. When there are three or more they are called a multiple star. The closer the stars are together the faster they move. The time it takes for them to go round each other varies from days to years. Some binaries are so close that gravity pulls gas from one to the other, forming an accretion disc around the smaller star in a binary system. This releases X-ray s. A nova may also be formed by binary stars. Like this web site? Get the pocket book version with comprehensive index for only $8! Earlier 12 Billion Years ago Later ... Physical Environment Basic Information Further Information Other Hotu Pages Questions, Answers, Comments

37. Binary Stars Eclipsing binary stars. by John Talbot Three dimensional Java simulationof stars that move about each other in elliptical orbits http://www.achilles.net/~jtalbot/glossary/binary.html

Eclipsing Binary Stars by John Talbot Three dimensional Java simulation of stars that move about each other in elliptical orbits whose orientation with respect to the observer is such that an eclipse will occur when one passes in front of the other. Your browser doesn't support Java, the above image is what you would see. Bug : move mouse off panel after changing sliders. Panel Description Light Curve Plots the light intensity variations during one orbit. The orbital phase can be set by clicking in this window (this will stop the animation if one is runnning). You can also click and while holding down the mouse button drag the mouse horizontally for more precise control over the animation speed and direction (bug: currently disabled). Earth Perspective Three dimensional animation of the binary star system. By clicking in this window you can stop and restart the animation. Blue Star Controls the luminosity, radius and mass of the blue star member of the system. Red Star Controls the luminosity, radius (in units of orbital seperation) and mass of the red star member of the system. Orbital Parameters Controls the orbit inclination, eccentricity (disabled) and the number of light samples (disabled) during one orbit.

38. Starfire Optical Range - Imagery (Binary Stars - More Binary Stars) home / imagery / more binary stars binary stars in. Ursa Major, Cancer,and Delphinus. As explained in detail in The Astronomical http://www.de.afrl.af.mil/SOR/binary2.htm

Imagery Asteroids (Vesta and Ceres) Binary Stars Beta Del k-Peg more binary stars Capella Hyakutake Comet Leonids Meteor Trails Saturn ... imagery / more binary stars Binary Stars in Ursa Major, Cancer, and Delphinus As explained in detail in The Astronomical Journal for January 2000, (Volume 119, pages 378-389), the Starfire Optical Range made extensive observations of selected binary stars, both with and without a guide star laser. The binaries are shown below, where a star observed without adaptive optics would occupy the entire field of view in each image. 10 Ursae Majoris had a separation of 0.498±0.004 arc seconds and a large magnitude difference of 1.783±0.021. phi Ursae Majoris was separated by 0.245"±0.002", with a magnitude difference of 0.277±0.026. 81 Cancri was barely resolved at 0.123"±0.001", and its magnitude difference of -0.120±0.042, indicates that the historically fainter companion is brighter at the wavelength of observation here, 0.85 microns. kappa Ursae Majoris, at a separation of 0.067"±0.001" and a magnitude difference of 0.63±0.14 magnitudes, only shows an elongation, but through detailed mathematical processing its parameters are determined. Based on this observation and other recent high-resolution measurements, a new orbit has been derived for this pair.

39. Starfire Optical Range - Imagery (Binary Stars - Beta Del) home / imagery / beta del Beta Del. Download an annotated copy Fullsize GIF(33K). JPEG(25K). BetaDel (0.199 arcsec) uncompensated http://www.de.afrl.af.mil/SOR/beta_del.htm

Imagery Asteroids (Vesta and Ceres) Binary Stars Beta Del k-Peg more binary stars Capella Hyakutake Comet ... imagery / beta del Beta Del Download an annotated copy: Full size GIF(33K). JPEG(25K). Beta-Del (0.199 arcsec) uncompensated and compensated (both images are on the same intensity scale). Download an annotated copy in: JPEG(37K). Beta-Del (0.199 arcsec) uncompensated and compensated (images are independently auto-scaled). Questions, comments and suggestions can be directed to the SOR Webmaster

40. PROJECT CLEA: ECLIPSING BINARY STARS Clea Home Page, ECLIPSING binary stars, Please sign our mailing list.MAC VERSION. Required Software. Click Filename to Download Or Icon http://www.gettysburg.edu/academics/physics/clea/binstlab.html

Clea Home Page ECLIPSING BINARY STARS Please sign our mailing list MAC VERSION Required Software Click Filename to Download Or Icon to Go to FTP Site FindEB.sea.hqx -Executables FindEB.README -Installation Instructions Mac User's guide (Acrobat pdf format) Mac Student manual (Acrobat pdf format) Questionnaires and Pre/Post-Tests (Acrobat pdf format) A Description of the Lab: Purpose: To understand the observation problems involved in identifying eclipsing binary stars. To understand how to determine the period of a variable star from irregularly sampled measurements of its brightness. These two labs developed by Claud Lacy of the University of Arkansas simulate eclipsing binary stars. FindEB uses a set of 150 CCD frames, obtained by a simulated automatic telescope, of a star field containing an eclipsing binary stars. The images include the effects of astronomical "seeing" variations and atmospheric transparency variations from night to night. The object is to identify which star in the field is the eclipsing binary star. In FindPeriod, the object is to determine the orbital period of an eclipsing binary star to 6-digit accuracy from the same 150 magnitude observations used in FindEB. Both programs make use of the same data sets of measurements of magnitudes; 81 of these data sets are provided with the lab material, with provision for generating additional data sets to the user's specifications. [AVAILABLE FOR COLOR MAC ONLY]

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