8B30.35 - Binary Star System - Eclipsing Binary or Trinary

Code Number:
Demo Title:
Binary Star System - Eclipsing Binary or Trinary
Area of Study:
Stellar Astronomy
Computer and Vernier Interface, Light Sensor, Magnetic Battery Powered Light Bulbs, Rotating Platform (PASCO) or Lazy Susan Platform, Various Size Balls on Sticks, Cenco Rotator Unit and small Binary Apparatus.

Use either the PASCO powered rotating platform or the lazy susan one you can turn by hand.  Both will work but the powered platform may give smoother and more reproducable light curves.  Place two of the lights (suns) so that one is approximately 5 cm from the center of the platform and the other at a distance of about 13 cm on the opposite side of center.  Set the light sensor to the 600 LUX range and bring it close enough to the bulbs so that it reads about 300 LUX when the bulbs are on the first setting.  Rotate the platform and hit collect.  An option is to use the dimmer second setting for one of the "suns".

No advanced preparation needed for the 2-ball systems.  Note that one of the systems models a red giant star with a small regular star or white dwarf binary.  This model has a center of mass that is inside the red giant star as indicated by the pink string.

The chalk boards in LR I and LR II are magnetic so it is just a matter of carrying the apparatus to that room.  In LR 70 you will have to move in the magnetic blackboard optics board for this demo as the chalkboard is not magnetic is that room.

A trinary sun system can be done by placing a third "sun" at the indicated position on the rotating platform.  You can vary the light intensity of any of the "suns" using either the 1st or 2nd setting.

Note: This small binary apparatus is kept in the 1J10.09 "Center of Mass Demos" box.  The small binary apparatus is designed to be used with the Cenco Rotator Unit.  Secure the apparatus in the chuck of the unit and slowly increase the rotation rate until a center of mass of the system is observed.

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Disclaimer: These demonstrations are provided only for illustrative use by persons affiliated with The University of Iowa and only under the direction of a trained instructor or physicist.  The University of Iowa is not responsible for demonstrations performed by those using their own equipment or who choose to use this reference material for their own purpose.  The demonstrations included here are within the public domain and can be found in materials contained in libraries, bookstores, and through electronic sources.  Performing all or any portion of any of these demonstrations, with or without revisions not depicted here entails inherent risks.  These risks include, without limitation, bodily injury (and possibly death), including risks to health that may be temporary or permanent and that may exacerbate a pre-existing medical condition; and property loss or damage.  Anyone performing any part of these demonstrations, even with revisions, knowingly and voluntarily assumes all risks associated with them.