CTIO REU 1999 Student Project
Jessica Kim-Quijano
Towson University
Project Title:
The Orbital Period of the Double-lined Cataclysmic Variable Phe 1
Advisor:
Donald W. Hoard
Abstract
We present an orbital period for the double-lined
cataclysmic variable (CV) Phe 1, derived from time-resolved
CCD photometry using the 0.9-m telescope at the Cerro Tololo
Inter-American Observatory. The CV nature of Phe 1 was first
confirmed spectroscopically in 1997; in
addition to emission lines of H I and He I,
TiO bands characteristic of the late type secondary star
were observed. A period of 0.27 d has been determined
with the Phase Dispersion Minimization algorithm from the
differential V and I light curves taken over 6 consecutive
nights in 1998. The light curves show a full range of
variation of approximately 0.7 and 0.4 mag in V and I,
respectively. When the data are folded on this period,
two orbital minima of different depths are observed.
Three mechanisms may contribute to the variability
observed in Phe 1: primary and secondary eclipses,
ellipsoidal variation of the distorted
secondary star, and/or viewing of its irradiation-heated inner
face. A radial velocity study to determine the component
masses is currently underway.
Figures:
Figure 1: Representative single-night I-band differential light curve, Phe 1 - C1 (red circles), and the light curve of two comparison stars, C2 - C1 (green triangles).
JPG (34kb) or Postscript (74kb)
Figure 2: Representative single-night V-band differential light curve, Phe 1 - C1 (blue circles), and the light curve of two comparison stars, C2 - C1 (green triangles).
JPG (33kb) or Postscript (74kb)
Figure 3: As in Figure 1, but for all 6 nights of observation.
JPG (74kb) or Postscript (270kb)
Figure 4: As in Figure 2, but for all 6 nights of observation.
JPG (70kb) or Postscript (263kb)
Figure 5: All 6 nights of I-band differential light curve folded on an orbital period of 0.27 days.
JPG (68kb) or Postscript (773kb)
Figure 6: All 6 nights of V-band differential light curve folded on an orbital period of 0.27 days.
Note that the V-band light curve shows significantly more scatter than does the I-band light curve in all of the figures;
this is probably due to the fact that the I-band more effectively samples the light contribution from the secondary star and cool, outer accretion disk, while the V-band samples light originating in the hot, active inner disk.
The latter band is therefore most affected by the ``flickering'' that is a hallmark of the photometric behavior of cataclysmic variables.
JPG (73kb) or Postscript (773kb)
1999 CTIO REU Program: Jessica's Project
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by ctioreu@noao.edu
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