1. Eclipsing Binary Stars ECLIPSING binary stars. Online Articles An Atlas of OC Diagrams of Eclipsing binary stars. Stars from binary stars A Pictorial Atlas http://www.physics.sfasu.edu/astro/binstar.html

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2. Binary Star Simulation ORBITING binary stars. Astronomy 101/103 Terry Herter. 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. A simplified derivation of the magnitude of the reflex motion of the star due to an orbiting planet can be found here 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.

3. Binary Stars 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 selfeducation see also Dan 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.

4. 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

5. Binary Stars 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. of the stars visible to us are visual binary stars. Careful spectroscopic studies 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. Binary Stars binary stars By Don Ware. Looking through a telescope at the much mass do 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.

8. X-ray Binary Stars - Introduction Xray binary stars. What is a Binary Star System? X-ray Binaries. A special class of 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!

9. APOD: February 19, 1997 - Mizar Binary Star In fact, most stars are binary stars. In a binary star system, each star of the pair follows and Mizar B, are themselves binary stars! But, the companions are 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

10. HR Diagram A single introductory astronomy lecture on binary stars, including several useful diagrams. http://zebu.uoregon.edu/~js/ast122/lectures/lec11.html

Hertzsprung-Russell Diagram In 1905, Danish astronomer Einar Hertzsprung, and independently American astronomer Henry Norris Russell, noticed that the luminosity of stars decreased from spectral type O to M. They developed the technique of plotting absolute magnitude for a star versus its spectral type to look for families of stellar type. These diagrams, called the Hertzsprung-Russell or HR diagrams, plot luminosity in solar units on the Y axis and stellar temperature on the X axis, as shown below. Notice that the scales are not linear. Hot stars inhabit the left hand side of the diagram, cool stars the right hand side. Bright stars at the top, faint stars at the bottom. Our Sun is a fairly average star and sits near the middle. A plot of the nearest stars on the HR diagram is shown below: Most stars in the solar neighborhood are fainter and cooler than the Sun. There are also a handful of stars which are red and very bright (called red supergiants) and a few stars that are hot, but very faint (called white dwarfs). We will see in a later lecture that stars begin their life on the main sequence then evolve to different parts of the HR diagram. Most of the stars in the above diagram fall on a curve that we call the main sequence. This is a region where most normal stars occur. Normal, in astronomy terms, means that they are young (a few billion years old) and burning hydrogen in their cores. As time goes on, star change or evolve as the phyisics in their cores change. But for most of the lifetime of a star it sits somewhere on the main sequence.

11. 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.

12. APOD Index - Stars: Binary Stars Astronomy Picture of the Day. Index Stars binary stars In fact, most stars are binary stars. In a binary star system, each star of the pair follows an elliptical 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.

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 BASIC Subroutine 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.

14. The Big Occulting Steerable Satellite Mission 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. 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: Italian translation added New: Now supports OpenGL animations New: Support for parallelization based on MPI 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').

16. 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 ... 2004 Page Charge Authorization Form (PDF) 2003 Page Charges (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

17. Ask A High-Energy Astronomer: Binary Star Systems Resources for this Topic. Imagine the Universe! X-ray binary stars. Imagine the Universe! binary stars. Library of Past Questions Binary Star Systems. http://imagine.gsfc.nasa.gov/docs/ask_astro/binary.html

Imagine Home Ask A High Energy Astronomer Current page Physics of Stars Black Holes Neutron Stars/Pulsars Resources for this Topic Imagine the Universe! - X-ray Binary Stars Imagine the Universe! - Cataclysmic Variables Binary Stars Library of Past Questions Binary Star Systems First time visitors: Please be sure to read our main page Check out the resource links. These are the sites we often point to in answering your questions. Browse through the library of questions below. Also try our Ask a High-Energy Astronomer Search Engine! If your question is still not answered, follow the link at the bottom of this page Library of Past Questions and Answers X-ray Binaries What is Cygnus X-1? What is the cause of X-ray bursts ? Cataclysmic Variables What is the smallest nova ever found? What is an accretion disk in a binary star system? Binary Star Systems (general) Why are binary stars interesting? How do binary stars get detected when you can't see them? What percentage of the stars are binary systems? Could planets exist in stable orbits around binary stars? ... How are binary star systems formed? Do you have a question that isn't answered in our archive? We do not answer homework questions.

18. 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 Astronomical Events TAU AstroClub Venus Transit ( 8/Jun/2004 ) - Hebrew Press Release: HD41004 - A rare configuration of a binary star, a brown dwarf and a planet (Jul/2003) Press Release: An extragalactic supernebula confined by gravity (Jun/2003) 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 Observatory Nightly Logs (Local access only) Submit Log Log Lookup Table Research: Announcements Publications Projects Tauvex Concam Spaceguard 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 Venus Transit Website - Hebrew

19. Nightfall Eclipsing Binary Star Program It can produce animated views of eclipsing binary stars, calculate synthetic lightcurves and radial velocity curves, and eventually determine the bestfit http://www.lsw.uni-heidelberg.de/users/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: Italian translation added New: Now supports OpenGL animations New: Support for parallelization based on MPI 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').

20. ESA - Science - LISA Overview 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.esa.int/science/lisa

ESA Home Extreme space Space sensations ... Space for you LISA overview Status In development Objective Detecting gravitational waves is the goal of ESA's future LISA mission. LISA will search for gravitational radiation from astronomical sources, testing the fundamental theories of gravitation. Bookmark this page as: For more in-depth scientific and technical details of our Space Science Programme and missions, follow this link. Contents Mission What's special? Spacecraft Journey ... Search Resources Reference section Glossary FAQs Downloads Sounds from space Services Calendar Help Subscribers Science missions BepiColombo Cassini-Huygens Cluster Corot Cos-B Darwin Double Star Eddington Exosat Gaia Giotto Herschel Hipparcos Hubble Hyper Integral ISO IUE JWST LISA Mars Express Planck Rosetta SMART-1 LISA Pathfinder SOHO Solar Orbiter Ulysses Venus Express XEUS XMM-Newton Space Science About Space Science Search All Space Science Advanced Search LISA (Laser Interferometer Space Antenna) line drawing Mission The Laser Interferometer Space Antenna (LISA) is a joint mission with NASA. It is a three-spacecraft mission, designed to detect the 'ripples' in space given out when very massive objects undergo strong acceleration. For example, they are produced when a black hole swallows a massive neutron star. Such ripples are called 'gravitational waves' and LISA will be the first mission to try and detect them from space. To achieve that goal, the relative position of several solid blocks placed in different spacecraft, 5 million kilometres apart, will have to be constantly monitored with high accuracy using laser-based techniques. A gravitational wave passing through the spacecraft will change the separations between them, thereby revealing itself.

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