AAS 199th meeting, Washington, DC, January 2002
Session 90. $\delta$ Scuti and Mira Variables
Display, Wednesday, January 9, 2002, 9:20am-6:30pm, Exhibit Hall

## [90.04] Aperiodic Behavior in the Dwarf Cepheid RY Leporis

M. D. Joner (Brigham Young University), C. D. Laney (South African Astronomical Observatory), L. R. Schwendiman (Brigham Young University)

Published optical photometry along with new JK observations from 1985-97 seemed to indicate that RY Leporis was a bright, stable, and easily observed monoperiodic dwarf Cepheid. These properties along with a moderate southern declination made RY Lep a primary target in our campaign to calibrate the period-luminosity relation for dwarf Cepheids using an IR Baade-Wesselink technique used previously for classical Cepheids.

We were surprised to find that observations from the first quarter of 2000 show aperiodic variations quite inconsistent with previous observations. The observations from early 2000 were unsuitable for inclusion in our investigation. Subsequent observations reveal a return to the previously observed monoperiodic variations with only a slight change in period.

This paper will present photometric VJ data and precision radial velocities from early 2000 and make comparisons to data from epochs considered to represent typical behavior. It is concluded that apart from occasional epochs of aperiodic behavior, RY Lep appears to have a normal temperature, radius, and luminosity for a dwarf Cepheid with a period of 0.225 days. It should also be noted that the radial velocities show that RY Lep exhibits binary motion. However, it is unlikely that binary interaction can explain the unusual cycles since the period is in excess of 500 days.