AAS Meeting #193 - Austin, Texas, January 1999
Session 21. The Distance Scale and Dark Matter
Oral, Wednesday, January 6, 1999, 10:00-11:30am, Room 8 (A,B,C)

[Previous] | [Session 21] | [Next]

[21.01] Comparison of Astrometric Measurements Among Multiple Techniques at Multiple Wavelengths for \theta2 Tau

Xiaopei Pan (California Institute of Technology), PTI Collaboration

The Hyades binary stars, such as \theta2 Tau, play important roles in the determination of astronomical distance scale. The extensive observations of this system have been done by different techniques in the past. Now the latest observations at various wavelengths from long baseline interferometers provide good opportunities to study physical pictures of the system of \theta2~Tau, and to compare measurement precision and accuracy claimed by different techniques.

Long baseline interferometers can determine all of seven orbital parameters of a binary system independently, and also provide accurate differential photometry between two components within separations of milli-arc-second (mas). Lunar occultation can determine projected separations with precision of sub-mas, and provide magnitude differences at multiple wavelengths. Radial velocity measurements can determine four orbital parameters, and mass ratio of two components.

It is interesting to compare measured results of \theta2 Tau that were derived from the above techniques, in particular, at various wavelengths. The comparison demonstrates the internal and external precisions of different techniques. The combination of the results of \theta2 Tau from interferometry and spectroscopy can determine the orbital parallax accurately, which can be compared with the Hipparcos parallaxes in order to check external errors of Hipparcos results independently. In addition, the masses of two components of \theta2 Tau have been determined accurately, and other fundamental parameters of \theta2 Tau, such as luminosities, radii, surface gravities, et al, have been analyzed.

If you would like more information about this abstract, please follow the link to http://astro.caltech.edu/~xpp/. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: xpp@astro.caltech.edu

[Previous] | [Session 21] | [Next]