Binary & Variable Star Links

Binary Stars

  • APOD Index - Stars: Binary Stars has a set of images of binary stars with useful descriptions from NASA's Astronomy Picture of the Day site.
  • Astronomy Lecture Notes - Binary Stars is a handy one-page summary of binary stars with examples and images.
  • Binary Star Motions provides a concise explanation, with diagrams, of how Kepler's Laws may be used to determine the mass of a binary system.
  • Multiple Star Systems has several pages that clearly explain the types of binary systems. It has excellent diagrams. Part of an extensive online lecture course, Astronomy 162, Stars, Galaxies and Cosmology at the University of Tennessee.
  • Spectroscopic Binaries provides a clear description of these systems. It includes diagrams showing how the Doppler shifting produces "split" lines and a radial velocity plot.
  • The Algol System explains the properties of this system and has useful diagrams. An animation shows the distorted shape of the K2 star in the orbiting pair.
  • The lives of binary stars is a small set of online slides with animations discussing the types of binaries, some history, evolution and importance of binaries in point form.
  • Weighing Ultra-Cool Stars is a press release from ESO explaining how VLT adaptive optics images were combined with those from the HST to measure the mass of an ultra-cool L-type star and its brown dwarf companion in a binary system. The page includes an animated gif image showing the orbits of the two objects.

Variable Stars

  • AAVSO: American Association of Variable Star Observers is an excellent site with a wealth of information and data on variable stars and eclipsing binaries. They have useful Power Point introductory talks, free software, a range of educational pages and the largest repository of variable star records in the world dating back a century. Their Hands-on-Astrophysics section has several activities for classroom use.
  • ASSA: Variable Star Group is part of the Astronomical Society of South Australia, an amateur society with a keen interest in variable star observations. Their site has a handy set of FAQs, star and binocular charts and a useful section on classification.
  • Cepheids and Distance to the LMC explains how variable stars are used to determine distances to nearby galaxies. Has useful diagrams and covers historical developments.
  • Cosmology with Supernovae - the High-Z SN Search site has a useful discussion of how supernova can be used to probe the size, geometry and fate of the Universe. Follow the pages through the Public section for details. This team was one of two that discovered evidence for an accelerating Universe, Science magazine's "Top Research Advance of 1998".
  • Hipparcos: Variable Stars has light curves for various types of variable stars based on photometric data from the Hipparcos Space Astrometry mission.

Catalogs & Sources of Binary & Variable Star Data

  • HST Key Project Home Page provides the photometric data for extragalactic Cepheids observed in the Key Project.
  • The Visual Binaries provides details on 150 visual binaries by coordinates or constellation. Orbital plots can be viewed as well as background information on the stars and constellations.
  • Washington Double Star Catalog maintained by the United States Naval Observatory is the world's principal database of astrometric double and multiple star information. It provides data on over 98,000 star systems.

Applets, Activities and Software

  • Astro 11 - Lab #13 Cepheid Distance is an exercise where you use Cepheid data from the HST observations of M100 to determine extragalactic distances. Some of the pages have animated gif images where you can see the extragalactic Cepheids changing in brightness over time.
  • Binary Star Simulation is an excellent Java applet from Cornell that allows you to alter the parameters for a binary system. You can view the radial velocity curves, the spectrum and a top-down and earth-view of the system. It comes with recommended examples and instructions. If this site is busy try the mirror site at Melbourne University.
  • Binary Stars has four free programs for Mac computers that can be downloaded from the site. Manuals are also available and useful for classroom or self-education use.
  • Determining the Extragalactic Distance Scale uses HST observations of Cepheids in the galaxy M100 to determine the distance to the galaxy. This activity has a number of animated gifs which are used to identify Cepheids and other variable stars. It has a number of useful supporting pages and explanations.
  • Eclipsing Binary Simulation is another excellent Java applet from Cornell. This one allows you to alter the system parameters to see what effect this has on the light curve produced by an eclipsing binary. Instructions and examples are provided.
  • Eclipsing Binary Simulator (EBS) is a free executable program for Win98 or higher PCs. With it you can visualise the orbit and light curve for an eclipsing binary system.
  • Eclipsing Binary Stars is an extensive site that provides free software downloads for Windows PCs plus detailed information on eclipsing binaries. There is a free program, StarLightPro and a range of Excel spreadsheets that allow you to investigate various properties of binaries. The page also has extensive categorised links for binary stars.
  • Light Curves - Hipparcos Space Astrometry Mission: Educational Resources discusses folded light curves for eclipsing binary and variable stars. It provides the photometric data in tabular form allowing for student analysis of different systems and interactive applets that you can use to determine the period of the light curve.
  • Orbital Characteristics of Spectroscopic Binaries is an activity where you can explore, using the online Java applet, how the parameters effect the radial velocity plots for a spectroscopic binary. There are several questions on the worksheet which can be printed out.
  • Roller Coaster Stars - Astronomy in Your Hands is an observational exercise where you observe a northern or southern hemisphere Cepheid variable star to produce a light curve and then determine the distance to the star. Whilst some of the material is only available to subscribers the method and theory are well explained and freely available. The Astronomy in Your Hands site is an excellent astronomy education resource for schools written by an experienced astronomy educator from New Zealand. A small subscription fee allows you to make class copies of well-tested resources and activities.