Proc. of the GHOU 2007 in Tokyo
Photometric observations of the cataclysmic variable star IP Peg Photometric observations of the cataclysmic variable star IP Peg
Kasumi GotoKasumi Goto*1*1 and and Ayano Terada Ayano Terada*1*1
© 2007, Japan Association for Hands-On Universe 1
Proc. of the GHOU 2007 in Tokyo
1. Introduction Cataclysmic variables (CVs) are close binary systems that consist of a white dwarf (primary) and a late-type star (secondary). The secondary transfers gas to the primary and an accretion disk is formed around it. The accretion disk shows various timescales of variations.
A sudden accretion onto the primary is observed as an outburst in which the magnitude
changes with an amplitude of 2-5 mag.
2. IP Peg
IP Peg is a 14th
magnitude eclipsing star in Pegasus, SS-Cygni type CV star whose period is 3.8 hours.
Fig.1 The model of
Cataclysmic variables (left) and position of IP Peg
3. Observation 3. Observation
Observations were made by a 40cm telescope at Kyoto University’s roof observatory for 2006 Dec. 23 18:53-21:25.
Automatic observation exposure time was 30
sec. Cloudy weather sometimes prevented our observations
4. Analysis 4. Analysis
Using the IRAF (the Image Reduction and Analysis Facility) and the Makali`i (Subaru image processing software), we obtained the stellar magnitudes using nearby comparison stars.
5. The light curveThe light curve
Fig.2 The observed light curve of IP peg
Ordinate: magnitude Abscissa:
time (hours)
The figure was obtained from the CCD observations.
6. 6. The simulations
Using IDL system at
Department of
Astronomy, Kyoto
University, the
inclinations and the angles of Hot Spot with
companion were
obtained. The simulation code is made by Sugiyasu-san (Kyoto University).
Fig.3
Relationship of the companion star Fig.4 Inclination and accretion disk, and Hot spot
The inclination is 85°
The inclination is 90 ° Angle of Hot Spot Angle of Hot Spot
with companion is 25°
with companion is 25°
Fig.5 The simulation light curve
7. Result 7. Result
Comparing the
simulations with observed light curves, we concluded that the inclination of IP Peg is 85°and the angle of the hot spot with the secondary is 25°, in fairly agreement with the previous results in which the inclination is 74°and angle of Hot Spot with companion is 20°
8. Acknowledgment 8. Acknowledgment
We thank staff of Department of Astronomy, Kyoto University.
© 2007, Japan Association for Hands-On Universe 2
Blue Red
*1 Rakutou High Scholl KYOTO, Japan
