1. 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. http://www.astro.cornell.edu/academics/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.

2. Binary Stars 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, 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.

3. Binary Stars Click here for some interesting Eclipsing Binary Star Facts. About the Author Claud H. Sandberg His main research area is binary stars (big surprise!). 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 to 9.2 (Classic Systems), or OS X running the Classic Environment, or OS X version 10.4 or greater. Adobe Acrobat Reader (free) for the manuals A printer may be needed in a lab setting Click below to read a brief program description Click below to download the free software now for the Classic Environment only Dates of Minima Binary Star Transit Click here to download ALL the software for Mac OS X (10.4 or greater). ... Click here for some interesting Eclipsing Binary Star Facts. About the Author: Claud H. Sandberg Lacy

4. X-ray Binary Stars - Introduction 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. http://imagine.gsfc.nasa.gov/docs/science/know_l1/binary_stars.html

What's New Site Map NASA Homepage Search: ... 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!

5. APOD Index - Stars: Binary Stars The brighter yellow star is itself a binary star system, but too close together to be resolved even with a telescope. Albireo, pictured above, is the fifth http://www.sai.msu.su/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.

6. 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

7. Eclipsing Binary Stars StarLight Pro produces animated views of eclipsing binary stars and calculate synthetic lightcurves. The effects of limb darkening, temperature, inclination http://www.midnightkite.com/binstar.html

E CLIPSING B INARY S TARS Site by Dan Bruton Basic Theory A Simple Light Curve Model [HTM] Limb Darkening Defined [HTM] Heliocentric Julian Day [HTM] Binary Star Lecture [PPT] Student Exercises [DOC] Advanced Theory StarLight Pro [EXE] Modeling Close Binary Stars [PDF] The Shape of a Rotating Star [PDF] Excel Worksheets Simple Light Curve Worksheet [XLS] Rotating Star Shapes [XLS] Roche Lobes [XLS] Lagrange Points [XLS] 3D Potential [XLS] Julian Day [XLS] Animations CK Boo GW Cep XY Leo StarLight Pro Free Download [EXE] Software StarLight Pro StarLight Pro produces animated views of eclipsing binary stars and calculate synthetic lightcurves. The effects of limb darkening, temperature, inclination, stellar size, mass ratio, and star shape are included. This is a free download for Windows. Binary View Windows software provided by Alexander Hobbs at Leicester University, UK. JAVA Simulations of Binary Stars JAVA Example from Cornell University. Eclipsing Binary Simulator EBS is a Windows astronomy application to visualise the orbit and synthetic light curve of binary star systems. It is made for educational purposes and for having fun. Binary Stars Free astronomical software for Macintosh computers, complete with manuals, teaching binary star concepts, for classroom or personal use. Nightfall Eclipsing Binary Star Program Nightfall 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. (Linux or Unix)

8. Eclipsing Binary Stars Free astronomical software for Macintosh computers, complete with manuals, teaching binary star concepts, for classroom or personal use. 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

9. APOD: February 19, 1997 - Mizar Binary Star 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 http://apod.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. Vast Cloud Of Antimatter Traced To Binary Stars Astronomers may have solved one of the most vexing mysteries in our Milky Way the origin of a giant cloud of antimatter surrounding the galactic center. http://www.sciencedaily.com/releases/2008/01/080109173722.htm

Science News Share Blog Cite Print Email Bookmark Vast Cloud Of Antimatter Traced To Binary Stars ScienceDaily (Jan. 10, 2008) See also: Black Holes Cosmic Rays Astrophysics Astronomy ... Star cluster Integral found that the cloud extends farther on the western side of the galactic center than it does on the eastern side. This imbalance matches the distribution of a population of binary star systems that contain black holes or neutron stars, strongly suggesting that these binaries are churning out at least half of the antimatter, and perhaps all of it. "The reported Integral detection of an asymmetry represents a significant step forward toward a solution of one of the major outstanding problems in high-energy astrophysics. I think I can hear a collective sigh of relief emanating from the community," says Marvin Leventhal, a University of Maryland professor emeritus and a pioneer in this field. The antimatter cloud was discovered in the 1970s by gamma-ray detectors flown on balloons. Scientists have proposed a wide range of explanations for the origin of the antimatter, which is exceedingly rare in the cosmos. For years, many theories centered around radioactive elements produced in supernovae, prodigious stellar explosions. Others suggested that the positrons come from neutron stars, novae, or colliding stellar winds. In recent years, some theorists championed the idea that particles of dark matter were annihilating one another, or with atomic matter, producing electrons and positrons that annihilate into 511-keV gamma rays. But other scientists remained skeptical, noting that the dark matter particles had to be significantly lighter than most theories predicted.

11. Monoceros It was here that Plaskett set about studying binary stars and in 1922 this work resulted in his discovering the very massive binary star which now bears his http://www.dibonsmith.com/mon_con.htm

Monoceros Transit Date of principal star: 16 January Flanked by Orion and Canis Minor, with Gemini above and Canis Major below, the faint constellation Monoceros ("the Unicorn") is often overlooked. While the constellation may have been in existence prior to the seventeenth century, its first historical reference appears in Jakob Bartsch's star chart of 1624, under the name "Unicornu". It is believed that Bartsch (who incidentally was Johannes Kepler's son-in-law) relied on earlier works, but such works have never been identified. It takes a lot of imagination to fashion a unicorn out of this group of stars. In fact, there are several variations. While our figure puts the horn in front, from gamma Monocerotis through epsilon and up to S Monocerotis, another popular form has the horn instead coming from delta Monocerotis through 18 Mon and over to epsilon. But it isn't the stars which hold most of our interest here. Instead, Monoceros has several celebrated deep sky objects as well as the most massive binary system yet discovered. The stars of Monoceros are as dim as the constellation's history: only a few fourth-magnitude stars that are difficult to notice except on very clear nights.

12. Digg - Vast Cloud Of Antimatter Traced To Binary Stars Four years of observations from the European Space Agency s Integral (INTErnational GammaRay Astrophysics Laboratory) satellite may have cleared up one of http://digg.com/space/Vast_Cloud_of_Antimatter_Traced_to_Binary_Stars

@import "/css/61/global.css"; @import "/css/61/forms.css"; @import "/css/61/permalink.css"; @import "/css/61/comments.css"; @import "/css/61/lightbox.css"; var pagetype = "permalink"; digg Join Digg About Login Username Password Remember? Search Digg... Popular Upcoming All News ... People Discover the best of the web! Learn more about Digg by taking the tour Vast Cloud of Antimatter Traced to Binary Stars Four years of observations from the European Space Agency's Integral (INTErnational Gamma-Ray Astrophysics Laboratory) satellite may have cleared up one of the most vexing mysteries in our Milky Way: the origin of a giant cloud of antimatter surrounding the galactic centre. Submitted: 14 days ago, made popular 13 days ago Submitter: cosmikdebris Share: Share Bury It: Bury Favorite: Favorite? diggs digg it Comments ( Who Dugg or Blogged It? Blog It Email It sort by most diggs sort by date (show all) sort by date (-10 or higher) sort by date (-4 or higher) sort by date (0 or higher) sort by date (+5 or higher) sort by date (+10 or higher) Hide Profanity Expand Full Tree Global Settings below viewing threshold show comment -11 diggs by josefresco on /insert computer binary joke here View replies to this comment (most popular has ... diggs) +58 diggs by perkonis on When I first read that I thought it said Britney Spears. I need to quit reading the front page so much.

13. 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.

14. Eclipsing Binary Stars (Article) 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 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.

15. BINARY STARS Double Star Observer , by Ronald C. Tanguay. A Professional Periodic Magazine about binary stars, write for the Professional and the Amateur Astronomer, 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 and Measuring Visual Double Stars , by Bob Argyle, Webb Society, 2004. * "Observación de estrellas dobles por aficionados”, by José Luis Comellas, Agrupación Astronómica Albireo ( July 1983 ). ( in spanish ) * "Astrophysics-A Topical Symposium", J.A. Hyek, 1951 * "Astrophysique Générale", J.C.Pecker et E.Shatzman, 1959. * “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. .

16. THE FORMATION OF BINARY STARS Recent observational investigations of the frequency of occurrence of premain-sequence binary stars have reinforced earlier suspicions that binary 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

17. Chandra :: Field Guide To X-ray Astronomy :: Binary And Multiple Star Systems The most common multiple star systems are those with two stars. These socalled binary stars have played an important role in many areas of astronomy, http://chandra.harvard.edu/xray_sources/binary_stars.html

Binary and Multiple Star Systems Chandra X-ray image of Sirius A (upper right) and Sirius B (lower left) (NASA/SAO/CXC) Stars, like people, are seldom found in isolation. More than 80% of all stars are members of multiple star systems containing two or more stars. Exactly how these systems are formed is not well understood. Some are thought to form when a collapsing cloud of gas breaks apart into two or more clouds which then become stars, or when one star captures another as a result of a grazing collision, or by a close encounter with two or more other stars. The most common multiple star systems are those with two stars. These so-called binary stars have played an important role in many areas of astronomy, especially X-ray astronomy. CXC Home Search Help Site Map ... Blog [News by email: Chandra Digest [Contact us: cxcpub@cfa.harvard.edu

18. Binary Stars forums.cpututorials.com. http://www.binarystars.com/

forums.cpututorials.com forums.cpututorials.com

19. IAU Symposium 200 : The Formation Of Binary Stars : Potsdam April 10-15 2000 The proceedings were published as ``The formation of binary stars , eds. H. Zinnecker R.D. Mathieu, IAU Symposium, Vol. 200, 2001, by ASP, IAU Volumes 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

20. The Evolution Of Compact Binary Star Systems We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). http://www.livingreviews.org/lrr-2006-6

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