Light Curve of XXCyg

1
Light Curve of XXCyg

• Cheryl Krugel
• Forrest McConnell
• Rosalie McGurk
• Julia Scheevel
• Tony Taliancich
• Christina Xu
• Advisor Dr. MEL BLAKE (1 Canadian, eh)

2
Constellation Cygnus

• RA 20.62, Dec 42.03
• The Swan
• Best visible in September
• Brightest star Deneb
• Zeus Leda
• Orpheus
• Cygnus
• Chinese Mythology

3
The Subject XXCyg

• Pulsating variable star of SX PHE type
• Ultrashort period dwarf Cepheids
• Cepheids Giant Yellow Star that pulsates
• Spectral Type A5
• Period of .135 days (Approx. 3.24 hours)
• Ideal for study because it is bright and has
  short period

4
Why are variable stars variable?

• Certain stars enter into a strip on the H-R
  Diagram where their sizes fluctuate because of an
  imbalance in internal forces
• As stars evolve, they can move through this
  region of instability
• By measuring the rate of increase or decrease in
  the period, we can monitor how quickly a star
  evolves

5
Goal

• To figure out how fast XXCyg is evolving by
  finding out the rate of period change as a part
  of Dr. Blakes research
• The Sky software
• CCD Camera
• Photometry
• IRAF software

6
Results
7
Results
8
Difficulties

• Only one good opportunity to observe the stars
• Mistake in the location of XXCyg
• Only around one hour of good data
• Did not obtain enough of the light curve to
  figure out the whole period
• However, we did obtain the peak of the curve (Our
  goal) through incredible luck and learned all of
  the applications that we set out to learn

9
Conclusion

• The rate of the period change (dP/de) for XXCyg
  is increasing at about 4.85 x 10-13 days per
  cycle, meaning that it is growing out of the
  instability strip indicated in the H-R Diagram

10
Bibliography

• http//en.wikipedia.org/wiki/Cygnus
• http//adsbit.harvard.edu/
• Dr. Mel Blake, Period Changes in SX Phoenicis
  Stars. II. XX Cygni