1. Eclipsing Binary Stars Information on binary stars and links to online articles.Category Science Astronomy Stars binary stars......ECLIPSING binary stars. What are binary stars? Most stars mass. One canclassify binary stars based on their appearance from earth. Stars http://www.physics.sfasu.edu/astro/binstar.html

E CLIPSING B INARY S TARS What are Binary Stars? Most stars are found in groups of stars that are gravitationally bound with each other. The majority of these stars are found in binary systems which are systems of two stars in orbit around a common center of mass. One can classify binary stars based on their appearance from earth. Stars that are far enough apart to be distinguished from each other are known as visual binaries . Other binaries are too close and far away to be seen separately but can distinguished using the doppler shift of their spectra. These are spectroscopic binaries In rare instances, such as with the star Algol the binary stars are close enough so that the eclipse one another. In this case, one can calculate not only the mass of the binary star systems, but also the radii of the stars. Online Articles A Simple Model for Computing Light Curves Photometry of 68 Herculis Watching Beta Lyrae Evolve Beta Lyrae Observations ... Photometry of Algol and Beta Lyrae Code Examples Computing Light Curves with Excel An Excel files with the code from the simple model article above. The binary star IT CAS is used as an example.

2. Binary Stars binary stars. free astronomy software for Macintosh computers, complete with manuals http://www.uark.edu/misc/clacy/BinaryStars

Binary Stars free astronomy software for Macintosh computers, complete with manuals teaches binary star concepts may be used in a classroom or lab setting, or for self-education for Windows operating systems, try the CLEA web site for educational astronomy software see also Dan Bruton's Eclipsing Binary Stars web site for observational lab exercises, see the URSA web site System Requirements: Any Macintosh, iMac, G3, G4, or other PowerMac computer running System 7.1 or better. Adobe Acrobat Reader (free) for the manuals A printer may be needed in a lab setting You may need the free software MacBinary II+ installed on an older Macintosh to automatically de-bin the files you will recieve from us, so get that first (if you need it) before you download our software. Click below to read a brief program description Click below to download the free software now Dates of Minima Binary Star Transit The software you get from us is compressed within the self-extracting archives (xxx.sea files). Just double-click the xxx.sea files (after the transfer and de-binning are complete) to extract all the software you need (your computer may automatically do this extraction for you, however). Click here for some interesting Eclipsing Binary Star Facts.

3. Interacting Binary Stars Nice clickthrough tour with some great animations about some of the complexities of Binary Systems. http://wonka.physics.ncsu.edu/~blondin/AAS/

HYDRODYNAMICS ON SUPERCOMPUTERS: INTERACTING BINARY STARS John M. Blondin North Carolina State University

4. Binary Star Simulation This is a representation of the binary star on a graphical and easy way.Category Science Astronomy Stars binary stars...... The observed velocities of the two stars, and the Doppler shifted spectral lines(as seen against the combined continuum from the two stars) are also shown in http://instruct1.cit.cornell.edu/courses/astro101/java/binary/binary.htm

O RBITING B INARY S TARS Astronomy 101/103 Terry Herter Description Instructions Example to try You need a JAVA enabled browser to view this simulation. This simulation is a bit unstable and may bring down the machine you are running. DESCRIPTION: Allows you to set the masses, orbital separation, orbital eccentricity, the inclination angle to our line of sight, and the angle of the nodes of an orbiting star pair. You see the privileged (from above the orbit) and the earth view of the system (which depends on the inclination angle). The observed velocities of the two stars, and the Doppler shifted spectral lines (as seen against the combined continuum from the two stars) are also shown in the upper rightbox. The spectral lines associated with each star are indicated and the unshifted line positions are also marked. The movement of the spectral lines against the continuum has been greatly exaggerated for display purposes, and the difference in brightness of the two stars has been ignored. We have the following definitions: Mass 1 or Mass 2 The mass of each of the two stars.

5. Binary Stars binary stars. By Don Ware http://astrosun.tn.cornell.edu/courses/astro201/binstar.htm

Binary Stars A binary star system consists of two stars which orbit around a common point, called the center of mass following Kepler's Laws Visual binaries are systems in which the individual stars can be seen through a telescope. Spectroscopic binaries are systems in which the stars are so close together that they appear as a single star even in a telescope. The binary nature of the system is deduced from the periodic doppler shifts of the wavelengths of lines seen in the spectrum, as the stars move through their orbits around the center of mass. In some instances, the spectrum shows the lines from both stars; this case is called a double-lined spectroscopic binary . In other cases, only one set of lines is seen, the other star being too faint, and we call the system a single -lined spectroscopic binary Eclipsing binaries are systems in which the orbital plane is oriented exactly edgewise to the plane of the sky so that the one star passes directly in front of the other, blocking out its light during the eclipse. Eclipsing binaries may also be visual or spectroscopic binaries. The variation in the brightness of the star is called its light curve.

6. THE FORMATION OF BINARY STARS Highlydetailed but brief paper concerning the Classical Fission Hypothesis. http://www.phys.lsu.edu/astro/nap98/bf.final.html

THE FORMATION OF COMMON-ENVELOPE, PRE-MAIN-SEQUENCE BINARY STARS J.E. TOHLINE , J.E. CAZES, AND H.S. COHL Louisiana State University , 202 Nicholson Hall, Baton Rouge, LA 70803-4001 U.S.A. 1. Introduction Recent observational investigations of the frequency of occurrence of pre-main-sequence binary stars have reinforced earlier suspicions that ''binary formation is the primary branch of the star-formation process'' ( Mathieu 1994 ). As Bodenheimer et al. have reviewed, a number of different theories have been proposed to explain the preponderance of binary stars. Klein et al. show how the direct fragmentation of protostellar gas clouds may occur in early phases of collapse (at cloud densities n = 10 cm ). But at higher densities, clouds are unable to cool efficiently upon contraction. Consequently, direct fragmentation becomes problematical. Because higher mean densities are associated with systems having shorter dynamical times, one is led to consider mechanisms other than direct cloud fragmentation for forming binary systems with orbital periods less than a few hundred years. Here we investigate whether such binaries can form by spontaneous fission of rapidly rotating protostars. 2. The Classical Fission Hypothesis

7. Stellar Evolution: Main Sequence A single introductory astronomy lecture on binary stars, including several useful diagrams. http://zebu.uoregon.edu/~js/ast122/lectures/lec11.html

Main Sequence Stars Once a protostar starts burning hydrogen in its core, it quickly passes through the T-Tauri stage (in a few million years) and becomes a main sequence star where its total mass determines all its structural properties. The three divisions in a stellar interior are the nuclear burning core, convective zone and radiative zone. Energy, in the form of gamma-rays, is generated solely in the nuclear burning core. Energy is transfered towards the surface either in a radiative manner or convection depending on which is more efficient at the temperatures, densities and opacities. The interior of three stellar types are shown below. Note that an O star is about 15 times larger than a G star, and a M star is about 1/10 the size of a G star, this scale is shown below the interiors. This scale, on the other hand, displays the absolute sizes. Notice how the nuclear burning regions takes up a larger percentage of the stellar interior as one goes to low mass stars. High mass stars have a very small core surrounded by a large envelope. The energy released from the stellar core heats the stellar interior producing the pressure that holds a star up. If stars were like cars, then they would burn their core hydrogen until they ran out and the star would fade out. But fusion converts hydrogen into helium. So the core does not become empty, it fills with helium `ash'.

8. ASU - Noble Science And Engineering Library - BINARY STARS of the Prairie Astronomy Club. Eclipsing binary stars Information on binary stars and links to online articles. http://www.asu.edu/lib/noble/space/binary.htm

Science Reference Room BINARY STARS (NASA photo) TABLE OF CONTENTS FINDING INFORMATION IN NOBLE LIBRARY INTERNET RESOURCES FINDING INFORMATION IN NOBLE LIBRARY Subject Categories Broad and Specific Terms Double stars Related Terms : Binary stars, Cataclysmic variable stars, Eclipsing binaries, X-ray binaries, Specific names of double stars (e.g., Cygnus X-3, SS433) Indexes and Abstracts for Journal Articles : The best index is Inspec . Also Science Citation Index Expanded is a good source. For full text online use EBSCOHost INTERNET RESOURCES CONTENTS BINARY LIBRARY ECLIPSING BINARY STARS HUBBLE SPACE TELESCOPE IMAGES ROSSI X-RAY TIMING EXPLORER ... BINARY LIBRARY This CHARA (Center for High Angular Resolution Astronomy) web site provides a bibliography on binary stars for sources form 1993 through 1996. Abstracts are included, and most are English language sources, though a few are in French. Other resources and links are provided as well. Neither the library nor the CHARA web pages can be accessed directly. Therefore, when you have entered this site click on CHARA, and then the Double Star Library. ECLIPSING BINARY STARS Online articles of the Photometry of 68 Herculis Watching Beta Lyrae Evolve A Simple Model for Computing Light Curves , and Beta Lyrae Observations are included at this web site. There are also software that can be downloaded for light curve computation and simple animation, world wide links on variable stars and binaries, a double star library, and more.

9. Educational Observatory - Binary Stars double stars, variable stars and binary stars? Eclipsing binary stars What are binary stars? Most stars are found http://www.edu-observatory.org/eo/binary_stars.html

Binary Stars What are the differeces between double stars variable stars and binary stars Eclipsing Binary Stars - What are Binary Stars? Most stars are found in groups of stars that are gravitationally bound with each other. The majority of these stars are found in binary systems which are systems of two stars in orbit around a common center of mass. One can classify binary stars based on their appearance from earth. Stars that are far enough apart to be distinguished from each other are known as visual binaries. Other binaries are too close and far away to be seen separately but can distinguished using the doppler shift of their spectra. These are spectroscopic binaries. Some of the "Astronomical Seeing" Scales Astronomical Seeing Fix: Chapter 21 Binary Star Systems Interactive Star Atlas ... The Formation of Binary Stars - Recent observational investigations of the frequency of occurrence of pre-main-sequence binary stars have reinforced earlier suspicions that "binary formation is the primary branch of the star-formation process". A number of different theories have been proposed to explain the preponderance of binary stars. Klein et al.

10. Accretion Disk Polar Jetting, Binary Star Formation And Nemesis Brief scientific paper on accretion disk polar jetting by Max Domaschko, PhD, So. Charleston, WV, USA. Also links to a small page of hubble photographs of jetstreams from young stars. http://www.aplg.com/nemesis.htm

On The Mechanics of Star Formation Binary Stars and Nemesis So. Charleston, WV, USA, May 12, 1996 The Hubble Telescope has provided perplexing images of star formation . Gone is the old theory of a simple collapse of a space cloud into a solid ball. Gone also is the theory of a simple accretion disk gradually winding its way to forming star. We now see volumous jets of material mysteriously being "ejected" along the axis of the accretion disk at high velocity and extending light years out from the disk center. In addition massive quantities of material are seen as blobs at some distance from the visible outer ends of the jets. What can explain these newly observed phenomena? The star is not ejecting material but simply holding material in orbit. Outflows could be buildups of otherwise incoming particles retarded by impulses from the outer reaches of the "jetting" orbital particles. Illumination is provided by heating due to collisions between particles. Observed beading within a jet may be due clumping within the original dust cloud. The accretion disk is not a barrier to material reaching the star's core. The disk is there as a storehouse for the angular momentum imbalance of the incoming dust cloud. It varies in size, shape, and orbital plane throughout star formation as dictated by dust particles within its influence. What happens as a star system's development matures? We know from our own solar system that an accretion disk can condense into planets which orbit the star in the plane of the original accretion disk. But what happens to any polar ejectate material in a highly eccentric elliptical polar orbit? It is possible that it may also condense into a sizeable body. Depending on its size it would be another star ranging from very bright to dark or it could even be a large planet.

11. BINARY STARS binary stars GROUP The binary stars group mainly concentrates on the synthesis of observable quantities for interacting binaries. The observables are spectral energy distributions due to circumstellar gas (Dirk Terrell and R.E. http://www.astro.ufl.edu/~fsgc/bstars/bstars.html

B INARY S TARS G ROUP The Binary Stars group mainly concentrates on the synthesis of observable quantities for interacting binaries. The observables are spectral energy distributions due to circumstellar gas (Dirk Terrell and R.E. Wilson), photospheric absorption line profiles for rotating stars (Jaydeep Mukherjee and R.E.Wilson), and the Stokes parameters of circumstellar polarization and limb polarization (R.E. Wilson and J.C.Liou). Dirk Terrell's hydrodynamical model has been combined with the Wilson-Liou polarization model. The ultimate goal is to understand binary star mass transfer, mass loss, and formation of particularly interesting or unusual objects. R.E. Wilson and T.J. Vaccaro are currently interested in studing long orbital period giant systems which may evolve into cataclysmic variables (dwarf + white dwarf interacting binaries) Faculty Dr. Robert Wilson Graduate Students Todd Vaccaro Department of Astronomy Home Page

12. Nightfall Eclipsing Binary Star Program open source Linux/Unix Interactive program for computing synthetic lightcurves and generating animated views and best-fit models of eclipsing binary stars. http://www.lsw.uni-heidelberg.de/~rwichman/Nightfall.html

[Deutsch] Overview Details Download ... Requirements Overview Nightfall is an astronomy application for fun, education, and science. It can produce animated views of eclipsing binary stars, calculate synthetic lightcurves and radial velocity curves , and eventually determine the best-fit model for a given set of observational data of an eclipsing binary star system. It is, however, not able to fry your breakfast egg on your harddisk. Nightfall comes with a user guide, and a set of observational data for several eclipsing binary star systems. New: Now supports OpenGL animations, as well as parallelization based on the MPI standard. The screenshots show a lightcurve of the eclipsing binary star TY Boo (left), a snapshot of the animated simulation of the same star (middle), and the interactive Roche potential display (right). New: MPEG movie of OpenGL animation: output.mpg (300 kB) Details Nightfall is a mildly ultramundane code of baroque complexity (I like Verdi and Haendel on lazy sunday mornings - friday evenings are better with Iron Maiden and a good whisky). Nightfall is based on a physical model that takes into account the nonspherical shape of stars in close binary systems, as well as mutual irradiance of both stars, and a number of additional physical effects. Nightfall can handle a large range of configurations, including overcontact (common envelope) systems, eccentric (non-circular) orbits, surface spots and asynchroneous rotation (stars rotating slower or faster than the orbital period), and the possible existence of a third star in the system ('third light').

13. 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.physics.sfasu.edu/astro/ebstar/ebstar.html

ECLIPSING BINARY STARS A Simple Model for Computing Light Curves Dan Bruton astro@sfasu.edu 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 phase , for which one unit of time is the orbital period. Measured light curves for periodic variable stars are usually "folded", which means that successive cycles are plotted atop one another. An example of an experimentally measured light curve is given in Figure 1. Note that the vertical axis of the graph is labeled "magnitude" which is a logarithmic scale of brightness. Figure 1: Photometry of Beta Lyrae in 1992-1993.

14. The Big Occulting Steerable Satellite The Big Occulting Steerable Satellite (BOSS) mission is designed to provide improved resolution of closely spaced objects with comparable brightnesses (binary stars, microlensing events, ) and to facilitate separation of dim objects from nearby bright objects (such as planets around stars) http://boss.phys.cwru.edu/

Glenn Starkman, Craig J Copi, and the BOSS project are supported by NSF CAREER grant PHY-9600193 to CWRU, and by grants from the Department of Energy and NASA's Jet Propulsion Lab. Questions? Comments? e-mail us!

15. Eclipsing Binary Stars Eclipsing Binaries. When one star passes directly in front of the other,as viewed from Earth, we seen an eclipsing binary. An eclipsing http://astrosun.tn.cornell.edu/courses/astro201/bin_eclipse.htm

Eclipsing Binaries When one star passes directly in front of the other, as viewed from Earth, we seen an eclipsing binary An eclipsing binary occurs when the orbital plane of the binary system is exactly perpendicular to the plane of the sky.

16. WISE OBSERVATORY, Astronomy In Israel Research activities include imaging and photometry of planets, moons and comets, photometric and spectroscopic studies of novae, symbiotic stars and other cataclysmic variables, spectrophotometric studies of quasars and active galactic nuclei, photometry and spectroscopy of xray binaries, multi-color photometry of galaxies, studies of spectroscopic binary stars. Operated by Tel Aviv University. http://wise-obs.tau.ac.il/

Website Map Hebrew Website General Info Contacts ... Observations The Florence and George Wise Observatory DEPARTMENT of ASTRONOMY and ASTROPHYSICS Tel-Aviv University , Israel SEARCH Announcements Research Astro. in TAU ... Circulars Click on image for full size Wise Observatory News/Announcements First-light images from MAALA, the new 1-degree imager on the Wise 1m telescope (26/Nov/2002) National Geographic (Hebrew) article about the Wise Observatory (Feb/2002) Press Release: Tango between black hole and star remnant may explain cosmic explosion (21/Feb/2002) Press Release: Wise Observatory astronomers observe cosmic explosion (4/Feb/2002) Full Announcement List Observatory Site Info Description Pictures Equipment Weather Visitors Impressions Observations: Observing Time Allocation Schedule/Calendar Image Database Manual Research: Announcements Publications Projects Tauvex Concam Software Tools Databases: Wise Observatory Image Database INES - I UE ... Circulars (local user access) Astronomy in Tel-Aviv University: Astro - Department Personnel Seminars Wise Observatory Sackler Institute of Public Interest Wise Observatory Hebrew HomePage Image Gallery (Hebrew) Astronomical Events Sky Maps TAU Astroclub Observataries in Israel History of Jewish Astronomy Other Astronomy Resources Webmaster Friedel Loinger , E-mail: friedel@wise.tau.ac.il

17. The Astronomical Journal Founded in 1849 and published by the American Astronomical Society with an emphasis on observational papers. Its expanded coverage of quasars, galaxies, supernova remnants, and studies of the interstellar medium complements the more traditional areas of astronomy, including galactic structure and dynamics, astrometry, variable and binary stars, solar system studies, and cosmology. http://www.journals.uchicago.edu/AJ/home.html

Editor: Paul Hodge Sponsor: American Astronomical Society ISSN: 0004-6256 The Astronomical Journal Electronic Edition Editorial Office Home Page, Seattle Journal Description Information about Electronic Subscriptions List of Institutions Currently Registered Letter to Institutional Subscribers Registration Form Institutional Site License ... Letter, Registration Form, and Site License (PDF) Editorial Board Information for Authors General Instructions to Authors Electronic Submission Guidelines Key Words IAU Recommendations for Nomenclature ... Page Charge Authorization Form (PDF) Publication Agreement Form (PDF) Preparation of Word and WordPerfect Manuscripts General Instructions Special Instructions for Tables Special Instructions for Math How to Subscribe to ... AJ Order Single Articles or Back Issues AAS Centennial Volume (PDF) Review Of Related Interest from the University of Chicago Press Contact the Editorial Office Subscription Center ... Journals Division

18. Interacting Binary Stars binary stars interact in a variety of ways depending on Winds Collidingwinds in earlytype stars, wind accretion in high-mass XRBs, http://wonka.physics.ncsu.edu/~blondin/AAS/interact.html

Binary stars interact in a variety of ways depending on... Winds Colliding winds in early-type stars, wind accretion in high-mass XRBs,... Luminosity Surface heating by a companion X-ray source, photoionization of the wind in symbiotic stars, ... Magnetic Fields The strong stellar magnetic field in AM Her stars... Binary Separation Tidal effects in close binaries: large tides, distorted winds, synchronization, mass transfer,...

19. ESA Science - Future Science Projects LISA Project An ESA space mission to detect and observe gravitational waves from massive black holes and galactic binary stars in the frequency range 104 to 10-1 hz. Useful measurements in this frequency range cannot be made on the ground because of the unshieldable background of local gravitational noise. http://www.estec.esa.nl/spdwww/future/html/lisa.htm

20. Eclipsing Binary Stars ECLIPSING binary stars. This web page has moved to another site but this page willremain active for a while longer without updates. What are binary stars? http://www.isc.tamu.edu/~astro/binstar.html

E CLIPSING B INARY S TARS 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. Online Articles Photometry of 68 Herculis Watching Beta Lyrae Evolve A Simple Model for Computing Light Curves Beta Lyrae Observations Software Binary Stars Free astronomical software for Macintosh computers, complete with manuals, teaching binary star concepts, for classroom or personal use. Eclipsing Binary Stars 1.0a2 Dan's Windows program that computes light curves using a spherical star model and shows a simple animation. (258K) Binary v3.0 Dan's DOS program that simulates eclipsing binary stars and displays light curves. More Programs World Wide Information Tools for Variable Stars JAVA Simulations of Binary Stars The Astronomer Online - Variables Variable Star Email Explosions ... IAPPP What are Binary Stars? Most stars are found in groups of stars that are gravitationally bound with each other. The majority of these stars are found in binary systems which are systems of two stars in orbit around a common center of mass. One can classify binary stars based on their appearance from earth. Stars that are far enough apart to be distinguished from each other are known as

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