81. Transfer Mode: Binary Stars And Extended Objects Transfer Mode binary stars and Extended Objects. In Transfer Mode,the FGS scans its IFOV across a target to generate a timetagged http://www.stsci.edu/instruments/fgs/handbook/WWW/c03_science4.html

FGS Instrument Handbook for Cycle 11 Transfer Mode: Binary Stars and Extended Objects In Transfer Mode, the FGS scans its IFOV across a target to generate a time-tagged (40 hz) mapping between the position of the IFOV (in both X and Y) and counts in the four PMTs. These data are used to construct the interferogram, or transfer function, of the target via the relation S x A x B x A x B x as described in chapter 2. The data from multiple scans are cross correlated and co-added to obtain a high SNR transfer function. In essence, Transfer Mode observing is conceptually equivalent to sampling an object's PSF with milliarcsecond pixels. This enables the FGS to resolve structure on scales finer than HST's diffraction limit, making it ideal for studying close binary systems and/or extended objects. Figure 3.1 . Smaller separations result in merged S-Curves with modulation and morphology differing significantly from that of a single star. Figure 4.3 illustrates these points. By using point source S-curves from the calibration library one can deconvolve the composite observed transfer function of a binary star into component S-Curves (done by either Fourier Transforms or semi-automated model fitting) to determine the separation, position angle, and relative brightness of the components. If enough epochs of data are available, the time-tagged position angles and angular separations can be used to construct the apparent relative orbit, from which one can derive the parameters P, a, i and which define the true relative orbit. Note that the semi-major axis is an angular quantity; to convert it to a physical length, one must know the object's distance (which can be obtained from parallax measurements).

82. Simulations Of Mass Transfer In Binary Stars Simulations of Mass Transfer in binary stars. Introduction As a starexhausts its supply of hydrogen for fueling its internal nuclear http://www.princeton.edu/~ratliff/research/research.html

Simulations of Mass Transfer in Binary Stars Introduction: As a star exhausts its supply of hydrogen for fueling its internal nuclear reactions, it begins to swell in size as the surface layers become cool and reddened. Eventually, the star can become a red giant, many times larger than its size while in the hydrogen-burning phase of its life. If such a star happens to be a member of close binary system where two stars orbit about one another, it may be possible that the star becomes so distended that the surface layers feel a stronger gravitational attraction from the companion star than from the star to which they belong. In this case, the companion star is able to pull a stream of gas away from the giant star and onto itself. If the two stars are close enough, the stream actually impacts the companion star driving the temperatures in the gas up to millions of degrees Kelvin. After impact the material is reflected and begins to orbit the star forming an accretion disk. Description: Below is an image of the results of a two dimensional hydrodynamical simulation of just such a system

83. Young Binary Stars And Associated Disks Young binary stars and Associated Disks. Figure 1. The relative velocity ofthe binary stars' components as a function of their mean separation. http://hven.swarthmore.edu/~jensen/preprints/ppiv.html

Young Binary Stars and Associated Disks The figures below are from the review article Young Binary Stars and Associated Disks , to appear in the proceedings of the meeting Protostars and Planets IV. Follow the link above to download the paper in various formats. Figure 1. The relative velocity of the binary stars' components as a function of their mean separation. The observed velocities are consistent with orbital motion since they (1) decrease with separation and (2) are generally greater for systems with higher mass primary stars (M and M are plotted as squares and circles respectively). The measurements are compared to that expected from a set of randomly oriented binary stars with total masses of 0.2, 1, 3, and 7 M . Although any individual total mass estimate is unreliable due to projection effects, the sample has an average total dynamical mass of ~ 1.7 M . (Taken from Ghez et al. 1995.) Figure 2. Location of TY CrA primary and secondary stars in the theoretical H-R diagram. The hatched regions designate high-confidence domains for the primary and secondary based on light-curve analyses. Dotted lines are drawn at constant radii. Solid and dashed lines correspond to pre-main-sequence tracks of Swenson et al. (1994), calculated for the masses of the TY CrA components at solar (solid curve) and Hyades (dashed curve) compositions. Open boxes and triangles mark isochrone points at ages of 3 x 10 yr and 10 x 10 yr, respectively. (Taken from Casey et al. 1998.)

84. Lecture 5 - Binary Stars (1/28/97) Lecture 5 binary stars (1/28/97). Prev Atmospheres - - EclipsingBinaries Next Reading Chapter binary stars with HST Some binary http://olddept.physics.upenn.edu/~www/inr/astro12-spring97/L5.html

Lecture 5 - Binary Stars (1/28/97) Atmospheres Eclipsing Binaries Reading: Chapter 12 (ZGS) Chapter 23 (Abell) HST Coronograph image of binary star Wolf 424, with separation of 0.4". The companion may be a brown dwarf. (Courtesy STSCI Key Question: How do you measure the masses of distant stars? Key Principle: Binary Stars and Gravitation Goal: Investigations: Weighing the Stars When did William Herschel discover that the Castor system was a binary star? What percentage of stars in the solar neighborhood are members of multiple star systems? Why are apparent doubles not considered real binary stars? How are binary stars used to determine stellar masses? How are the luminosity and temperature of stars measured? What are the four primary physical parameters of stars? What is a visual binary What is a spectrum binary Why are spectroscopic binaries useful? What can we learn from eclipsing binary systems? Orbital Mechanics Revisited Kepler's 1st Law states that orbits are ellipses with the Sun at one focus. How does this apply to binary stars? What is the eccentricity of an ellipse?

85. GAIA - The Galactic Census Project: Science With GAIA: Binary Stars & Multiple S GAIA Science. binary stars. In the area of binary and multiple starsGAIAs important contribution will be to make controlled statistical http://astro.estec.esa.nl/GAIA/science/Binary_Multiples.html

GAIA Science Binary Stars In the area of binary and multiple stars GAIAs important contribution will be to make controlled statistical studies of multiple star distribution functions. Resolved binaries GAIA will be unable to resolve binaries with separations below about 20mas. At separations of a few arcsec, even very faint secondaries can be detected. Resolved binaries will be studied in different populations of stars: nearby star-forming regions, open clusters and associations as well as field binaries of different ages. GAIA's high precision parallaxes and proper motions will also allow identifying the very widest binaries (amongst the individually observed stars) and studying their relation to common proper motion pairs and associations. GAIA's precision astrometry will also be exploited for visual binary orbit and mass determinations of unusual accuracy. Although the number of resolved orbital systems will be modest and only a fraction of these will have short enough periods for the orbits to be well-defined, the absolute numbers of new high-precision masses will be very impressive. Simulations of GAIA observations of thousands of close (20-100 mas) but resolved binaries have been performed. Analysis of the simulated data shows that the full set of orbital elements can be recovered for periods in the 4-40 year range. From the GAIA observations, more than 10000 masses accurate to 1 per cent can be expected. With these mass determinations detailed checks of the stellar evolution models can be made.

86. Interacting Binary Stars And Astronmical Instrumentation Interacting binary stars and Astronmical Instrumentation. Dr Vik Dhillon.Of the 9000 stars visible to the naked eye from the Earth http://www.shef.ac.uk/uni/academic/N-Q/phys/research/brochure/vsd.html

Interacting Binary Stars and Astronmical Instrumentation Dr Vik Dhillon Of the 9000 stars visible to the naked eye from the Earth, well over half are binary, consisting of two stars locked in gravitationally bound orbits. About half of them in turn, consist of interacting binary systems where two component stars are unable to complete their normal evolution without being influenced by the presence of the other. There are many different types of interacting binary stars, ranging from the so-called x-ray binaries, which contain black holes or neutron stars, to the cataclysmic variables (or CVs), which contain which dwarfs. Using large telescopes in Hawaii, Australia and the Canary Islands, Dr Vik Dhillon and his group specialise in optical and infrared studies of interacting binary stars, concentrating on their evolution and the study of their accretion discs. The group is also actively involved in developing the astro-tomographic techniques and in building astronomical instrumentation. Its latest project, ULTRACAM, is and ultra-fast, triple-beam CCD camera which is to be used on telescopes around the world to study interacting binaries on the shortest possible timescales. For further information, please consult the group's WWW pages at

87. Binary Stars binary stars. There are some excellent pages on binary stars on the WWW,so I will just provide some links rather than trying to repeat them. http://xmm.u-strasbg.fr/staff/ignacio/binstars.html

Binary Stars Stars are born from big clouds of gas, which collapse due to their own gravitational pull ( if you want to learn about star formation have a look at A star is born by Lee Carkner from the Penn State University ). In most cases, several stars are born from the same cloud and they remain gravitationally bound after their formation. For this reason, most stars are part of groups. The lonely Sun is an exception rather than the rule. The most common grouping is two stars orbiting around their common centre of gravity. This is known as a binary star. There are some excellent pages on binary stars on the WWW, so I will just provide some links rather than trying to repeat them. A nice introduction to binary stars with a description of their orbits at Cornell University . A slightly more technical introduction to binary stars , also at Cornell , provided by Prof. Terry Herter A similar introduction from the University of Wisconsin-Parkside Types of binary stars by Don Ware from the Peoria Astronomical Society How to measure the masses and other properties of binary stars by Dave Soper at the University of Oregon Physics Department Information for professionals on eclipsing binaries by Dan Bruton at the S.F. Austin State University

88. An Introduction To Close Binary Stars - Cambridge University Press The first book to provide a pedagogical and comprehensive introduction to binarystars for advanced students. An Introduction to Close binary stars. RW Hilditch. http://books.cambridge.org/0521798000.htm

Home Catalogue Related Areas: New titles Email For updates on new titles in: An Introduction to Close Binary Stars R. W. Hilditch Hardback In stock Binary systems of stars are as common as single stars. They are of fundamental importance because they allow stellar masses, radii and luminosities to be measured directly, and explain a host of diverse and energetic phenomena including X-ray binaries, cataclysmic variables, novae, symbiotic stars, and some types of supernovae. This book is the first to provide a pedagogical and comprehensive introduction to binary stars. It combines theory and observations at all wavelengths to develop a unified understanding of binaries of all categories. It comprehensively reviews methods for calculating orbits, the Roche model, ideas about mass exchange and loss, methods for analysing light curves, the masses and dimensions of different binary systems, and imaging the surfaces of stars and accretion structures. This book provides a thorough introduction to the subject for advanced undergraduate and graduate students. Researchers will also find this to be an authoritative reference. Reviews ‘Combining the experience of many years of teaching with an equal length of service in observational research on binary stars, Ron Hilditch has produced a book that will be a standard reference for advanced undergraduates, postgraduates, and more mature researchers for a long time to come I found this book inspirational.’David Stickland, The Observatory

89. ASTR2050 Intro A&A Exercise On Binary Stars Spectroscopic and Eclipsing binary stars. You will use the programto determine the orbit parameters of two actual binary stars. http://www.rpi.edu/dept/phys/Courses/Astronomy/Labs/binaries.html

Introductory Astronomy and Astrophysics Spectroscopic and Eclipsing Binary Stars Today you will use the CUPS Astrophysics module on Binary Stars to simulate a spectroscopic binary and an eclipsing binary. You will use the program to determine the orbit parameters of two actual binary stars. First, connect to the CUPS modules. Choose the module "astro" and it will bring up a list of programs. Choose "Programs on Binary Stars". You may want to play around with the programs a bit before you start in. 1) Find the mass of each of the two stars in HD 48099 The star called HD48099 can be resolved into a binary system of two stars with maximum separation 0.045AU. Its spectroscopic motion will allow you to determine the mass of each of the two stars. The period of revolution is 3.078 days. Assume the orbit is circular and the inclination angle is 90 deg. First, do a simple calculation to determine the sum of the masses of the two stars. Now choose the program "Make your own spectroscopic binary". Enter a trial set of masses and observe the spectrum. (Note that the periastron argument is irrelevant for circular orbits.) Do you get the right value for the period? If not, the sum of the two masses is wrong. Note that the program plots the velocity profile for star "A".

90. Lecture 8: Binary Stars (DePoy/Au98) Lecture 8 binary stars Stellar Masses Radii. Key Ideas binary stars. ApparentBinaries Chance projection of two distinct stars along the line of sight. http://www-astronomy.mps.ohio-state.edu/~depoy/courses/AST162_LECTURE_NOTES/Unit

Astronomy 162: Key Ideas: Types of Binary Stars: Visual Spectroscopic Eclipsing Can only measure masses for Binary Stars Radii are measured for very few stars Binary Stars Apparent Binaries Chance projection of two distinct stars along the line of sight. Often at very different distances. True Binary Stars A pair of stars bound together by gravity. Orbit each other about their center of mass. Between 20% and 80% of all stars are binaries Types of Binaries Visual Binary Can see both stars and follow their orbits over time. Spectroscopic Binary Cannot separate the two stars, but see their orbit motions as Doppler shifts in their spectral lines. Eclipsing Binary Can separate the stars, but see the total brightness drop when they periodically eclipse each other. Visual Binaries Two stars orbiting about their center-of-mass. Center of Mass Two stars orbit about their center of mass distance Relative positions about the center give: M /M = a /a Here are two movies showing visual binary stars, one with a circular orbit, the other with an elliptical orbit, emphasizing the point about their orbits around their common center of mass in all cases.

91. Background Information On Eclipsing Binary Stars Background Information on Eclipsing binary stars. The light curves of eclipsingbinary stars can reveal tremendous amounts of information. http://physics.unl.edu/directory/lee/astroed/applets2/ebs/back-ebs.html

Background Information on Eclipsing Binary Stars Binary stars whose orbits are inclined so that one star passes in front of the other star as seen from Earth are called eclipsing binary stars. Often it is not possible to resolve the individual stars in images - they appear as a single point of light. One knows that a system is an eclipsing binary from the periodic drops in brightness as one star obstructs the light from the other star. The light curves of eclipsing binary stars can reveal tremendous amounts of information. In addition to information on masses, the length of time that eclipses last tells astronomers about the relative sizes of the stars and their orbits. The correct nature of eclipsing binaries was first determined in 1783 by a young English astronomer named John Goodricke. Although Goodricke only lived to be 21 years old and he was not able to speak or hear, he made a number of important contributions to astronomy. He had been studying Algol ( b Persei), also known as the Demon Star. Algol is a second-magnitude binary system that drops to a third-magnitude system approximately every 69 hours. Goodricke suggested that the brightness variations were due to the presence of an unseen companion passing in front of the brighter star. It was more than 100 years later that his suggestion was shown to be correct. For a binary system to be an eclipsing binary, the orbital plane of the two stars must be seen nearly edge-on from our perspective. Astronomers describe this orientation using the parameter

92. Bibliography And Links For Eclipsing Binary Stars Bibliography and Links for Eclipsing binary stars. General Overview of binary starsI; General Overview of binary stars II; The Orbits of 150 Visual binary stars; http://physics.unl.edu/directory/lee/astroed/applets2/ebs/bib-links.html

Bibliography and Links for Eclipsing Binary Stars Web Resources Eclipsing Binary Stars - This site administered by Dan Bruton has many links to a wealth of information concerning binary stars. Links are provided to sites with eclipsing binary simulation software for many platforms. General Overview of Binary Stars I General Overview of Binary Stars II The Orbits of 150 Visual Binary Stars Animations of Visual Binary Systems at Ohio State University ... Link to a Spectrocopic Binary Applet at Cornell University Back to the Nebraska Astronomy Applet Project Home Page

93. Eclipsing Binary Stars Project - Collaboration Between Professional And Amateur This side is about collaboration between professional and amateurastronomers in binary eclipsing stars. Join us! Note This page http://stud.wsi.edu.pl/~sibetlem/gzz/

Note: This page in English version isn't finished and is under testing! Any suggestions please send to webmaster Main page Software Texts ... Links Eclipsing Binary Stars astronomy observers of the night sky Language: pl Language: en Description of the Project Our project is collaboration between professional and amateur astronomers This page is for the people who are interested in join to our programme of binary eclipsing stars' observations (short called GZZ). This programme is runing by Mt. Suhora Astronomical Observatory If you are interested in this project please contact with us sending an e-mail to ogloza@ap.krakow.pl or via mail to: Obserwatorium Astronomiczne Akademii Pedagogicznej, ul. Podchorazych 2, 00-084 Krakow, Poland. Also you can send to us questionnaire. It's available from this link ( get questionnaire ) ankieta.zip (5kB) Subject of our researches. Mt. Suhora Astronomical Observatory has been doing reserchaes of

94. Visual Binary Stars next up previous Next Eclipsing binary stars Up binary stars Previousbinary stars. Visual binary stars. The clearest evidence http://www-astro.physics.uiowa.edu/~srs/lec11/node5.html

Next: Eclipsing Binary Stars Up: Binary Stars Previous: Binary Stars Visual Binary Stars The clearest evidence for the existence of binary stars is provided by visual binary stars. We look at these stars in a telescope and see a pair of stars rather than just one. Look here for a picture of one Some prominent examples in the sky are the star Castor ( Geminorum) and Cygni. Figure 21.1 of your textbook shows the observations of Castor. Typically, the distance between the components of a visual binary star are many astronomical units of tens of astronomical units, and the periods are decades or even centuries. Steve Spangler Fri Sep 17 08:10:32 CDT 1999

95. Eclipsing Binary Stars next up previous Next Spectroscopic binary stars Up binary starsPrevious Visual binary stars. Eclipsing binary stars. Stars that http://www-astro.physics.uiowa.edu/~srs/lec11/node6.html

Next: Spectroscopic Binary Stars Up: Binary Stars Previous: Visual Binary Stars Eclipsing Binary Stars Stars that are too close to see as separate stars can show their binary nature via eclipses. In this, one star moves in front of the other and blocks its light. We see this as a drop in the brightness of the star. The basic idea is illustrated in Figures 21.8 and 21.8 of your textbook. Transparencies of Figures The best example of this type of star is Algol , or Persei. SC1 chart with Algol. Every two days and 21 minutes Algol drops in brightness for a period of about eight hours. The next few minima of Algol are as follows. September 23; 6 AM, September 26; 3 AM, September 28; midnight. Eclipsing binaries tend to have periods of a few days, down to under a couple of days. This corresponds to the time it takes the stars to go around each other, so obviously they are pretty close. Artists Conception of Beta Lyrae Image of Beta Lyrae. Ballpark separation between the stars in eclipsing binaries are about 10 million kilometers, or about 5 - 10 times the stellar diameters. Steve Spangler Fri Sep 17 08:10:32 CDT 1999

96. Binary Stars & Blending next up previous contents Next AGB Stars Up Effects that Complicate thePrevious Influence of Reddening Uncertainties. binary stars Blending. http://cepheid.cfm.udec.cl/~bdirsch/master/node28.html

Next: AGB Stars Up: Effects that Complicate the Previous: Influence of Reddening Uncertainties The observation of an unresolved binary, which is likely to make up a considerable fraction of observed objects, leads to a change in the photometric metallicity. Fortunately, this effect plays a negligible role for stars on the RGB where the mass-luminosity relation is steep and even small differences in the initial mass result in large differences in luminosity. This has been checked with the aid of synthetic CMDs and two-colour diagrams, which is described in Sec. 12 below. In crowded fields blending of stars is a related problem. The first correction is to exclude the most crowded inner part of the clusters. To estimate the probability of blending with other stars we used the following approach: We assumed that blending takes place if the luminosity centre of gravity of two stars is nearer than the PSF radius divided by (sampling theorem). Since the PSF radii are always around pixels the area in which only one unblended star can be is . Next we counted the stars on the blue and red side of the observed CMD (bluer and redder than (b-y)=0.4

97. Melton Memorial Observatory's Binary Stars Page Melton Memorial Observatory's binary stars Page. If we can see both stars or components,then we have a Visual binary, such as Epsilon Lyra and Alberio. http://astro.physics.sc.edu/htmlpages/Melton/ccdImages/Binaries/binary.htm

98. Eclipsing Binary Simiulation Orbiting stars which are separated by a small distance may pass in front of oneanother. Separation, The distance between the two stars in solar radii. http://instruct1.cit.cornell.edu/courses/astro101/java/eclipse/eclipse.htm

E CLIPSING B INARIES Astronomy 101/103 Terry Herter Description Instructions Example to try You need a JAVA enabled browser to view this simulation. DESCRIPTION: Orbiting stars which are separated by a small distance may pass in front of one another. It is not possible for astronomers to see the individual stars, but there will be a change in the total light coming from the two stars when they "eclipse" one another. This simulation shows how this eclipse happens. We have the following definitions: Inclination angle Angle of the orbital plane of the stars to our line-of-sight. o - edge on o - face on Separation The distance between the two stars in solar radii. Star 1 or Star 2 The spectral type of the stars. INSTRUCTIONS: Adjust the inclination angle, separation, and star types. Click "enter values" to update the simulation parameters. Use "pause" to start and stop the simulation, if desired. If the picture is messed up at anytime, use "clear graph" to redraw it. EXAMPLE TO TRY: Change separation to 6.

99. Michele's Home Page Information on research projects primarily dealing with variable stars (XX Leo eclipsing binary star, SMC variable stars, novae). Provides links to a growing number of astronomy, space, and science related sites. http://www.astro.psu.edu/users/stark/

100. HubbleSite - NewsCenter - 1997 - 26 - Hubble Separates Stars In The Mira Binary Hubble Space Telescope News Release/Paper about the discovery of the atmospheric interaction between the giant star Mira and its white dwarf companion star. http://oposite.stsci.edu/pubinfo/PR/97/26/PR.html

NEWS GALLERY DISCOVERIES FUN ... archive August 6, 1997 STScI-1997-26 Introduction Release Text Images Related Links Hubble Separates Stars in the Mira Binary System View all images Although the giant star Mira has been known for about 400 years, astronomers have had to wait for the Hubble telescope to provide the first ultraviolet-light images of the extended atmosphere of the cool red giant star and its nearby, hot companion. By giving astronomers a clear view of the individual members of this system, Hubble has provided valuable insights into other types of double-star systems where the stars are so close they interact with one another. In ultraviolet light, Hubble resolves a small, hook-like appendage extending from Mira and pointing towards the smaller companion. This material could be gravitationally drawn towards Mira's mate. Read the full press release text Credit: Margarita Karovska (Harvard-Smithsonian Center for Astrophysics) and NASA Cosmology Exotic Galaxy Miscellaneous Nebula Solar System Star Star Cluster Survey Find more Releases: About Star Binary Star From about us contact us glossary

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