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Session 44 - Double Stars.
Display session, Thursday, January 08
Exhibit Hall,
The Palomar Testbed Interferometer (PTI) is a long-baseline, K-band interferometer located at Palomar Observatory. During the 1997 observing season PTI has resolved the orbits of a number of small-separation, short-period spectroscopic binaries: alpha CrB, iota Pegasi, 64 Psc, and 47 And.
alpha CrB is a well-known eclipsing system (Tomkin and Popper 1986) with significant delta-K magnitude between primary and secondary ( 3.2 mag). 1997 PTI data is able to resolve the orbit despite this relatively large magnitude difference and limited u-v coverage. iota Pegasi is a double-lined system suggested by Fekel and Tomkin (1983) as a possible eclipsing system based on spectral type information, yet repeated photometric observation have failed to show evidence for eclipses. In our orbit we see the system as only 0.75 deg (roughly two sigma) away from apparent limb-to-limb contact, and consistent with the Fekel and Tomkin radial velocity work. 64 Psc is a nearly-equal mass system with a possible third component suggested by Nadal et al (1979) based on long-term variation in the spectroscopic orbital parameters. Our orbit based on 1997 PTI data is in good agreement with the 1979 spectroscopic parameters. Finally, 47 And is a double-lined system with a magnetic primary. The physical parameters and distances for these systems are all in very good agreement with expectations based on Hipparcos parallaxes.
