Poster Abstracts

Name/Affiliation:  Bob Zavala (US Naval Observatory)

Title:  A close look at a cool star in a triple system.

Algol binaries have cool secondary stars which exhibit magnetic activity, eclipses and have accretion streams. In addition to their optical variability they are radio and x-ray sources as well. Their relative optical brightness and radio emission makes them useful sources for registering the optical and radio astrometric reference frames. Here we report on observations with the Navy Precision Optical Interferometer (NPOI) and a variety of optical telescopes of the triple star b Per which is thought to host an Algol close binary. Our goal is to determine the evolutionary state of the cool star and to improve the optical orbit to aid the optical-radio reference frame astrometric registration.