Greek Letter Stars at Milli-arcsecond Resolution

Seminar Date:
June 26, 2013

Speaker:
Dr. Bob Zavala
Astronomer,
U.S. Naval Observatory, 
Flagstaff Station

Title:
Greek Letter Stars at Milli-arcsecond Resolution

Abstract:
The brilliant colors of the double star Albireo are often shown to students in introductory astronomy courses. The color differences elicit a "Wow" from the viewer, and this is usually followed by an explanation of colors and temperatures of stars. I'll attempt to re-create some of the "Wow" feeling as I present results of bright Greek letter stars (and one without a Greek letter) resolved on milli-arcsecond scales. Most observations were obtained with the Navy Precision Optical Interferometer (NPOI), a 6-element optical interferometer located in Flagstaff, AZ.

The NPOI resolves close stellar systems and our visual orbits are often combined with other datasets to provide a fairly detailed picture of the components. I'll show results on systems such as a massive O star binary, evolved mass-transferring systems and radio stars. I'll also present radio VLBI observations on similar spatial scales and show how they complement the astrophysical understanding of the sources. I will also discuss how our narrow-angle astrometry supports the Naval Observatory's bright star catalogs.