1. Pulsars: Astronomical Clocks In The Sky Team J: Ashley Randall Ashton Butts Priscilla Garcia Jessica Wilkinson Olivia Arrington

2. Introduction Pulsars are rapidly rotating neutron stars Pulsars are rapidly rotating neutron stars A neutron star is only ten kilometers in size A neutron star is only ten kilometers in size They are created in a supernova explosion near the end of a star’s life They are created in a supernova explosion near the end of a star’s life Pulsars spin at quick speeds ranging from milliseconds to seconds Pulsars spin at quick speeds ranging from milliseconds to seconds Single pulsars spin about once every second, and pulsars in binary systems spin thousands of times every second Single pulsars spin about once every second, and pulsars in binary systems spin thousands of times every second

3. Purpose To learn how to calculate the rotation period of a pulsar To learn how to calculate the rotation period of a pulsar To calculate the size of the pulsar’s orbit To calculate the size of the pulsar’s orbit To calculate the luminosity of the pulsar To calculate the luminosity of the pulsar

4. Methods Used NASA observations collected with the Chandra X-ray telescope Used NASA observations collected with the Chandra X-ray telescope Used the ds9 computer program to analyze the observations Used the ds9 computer program to analyze the observations

5. Materials DS9 computer program written by NASA DS9 computer program written by NASA DS9 instruction handbook DS9 instruction handbook Textbook: Horizons: Exploring the Universe by Michael A. Seeds Textbook: Horizons: Exploring the Universe by Michael A. Seeds Lecture Notes: Dr. M. Richards Lecture Notes: Dr. M. Richards Chandra X-ray Telescope archives: http://chandra.harvard.edu / Chandra X-ray Telescope archives: http://chandra.harvard.edu / NASA Chandra Education webpage NASA Chandra Education webpage http://chandra-ed.harvard.edu/activities.html

6. Procedures Load the light curve data from the Chandra archives Load the light curve data from the Chandra archives We measured the period directly from the light curve We measured the period directly from the light curve – Calculated the average period and standard deviation for the group. Light Curve: how light from the pulsar changes with time Light Curve: how light from the pulsar changes with time

7. Procedures The power spectrum finds any patterns in the light curve The power spectrum finds any patterns in the light curve – We calculated the period from the frequency: Period = 1. Frequency Frequency

8. Results Objects studied: Cen X-3, GK Per, Vela pulsar Objects studied: Cen X-3, GK Per, Vela pulsar GK Per Cen X-3 Star size = 6000 km Rotation period = 350.87 sec Star size = 10 km Rotation period = 4.807 sec

9. Results When we expand the power spectrum for Cen X-3, the peak looks broad When we expand the power spectrum for Cen X-3, the peak looks broad The light from the pulsar is blue-shifted and red-shifted because the pulsar is moving around another object The light from the pulsar is blue-shifted and red-shifted because the pulsar is moving around another object Measure the spin period and orbital period of Cen X-3 Measure the spin period and orbital period of Cen X-3 Pulsar moving away from us Pulsar moving towards us

10. Results Luminosity = 4  distance 2 x flux Cen X-3 Pulsar Vela Pulsar Size of star (km) 1010 Distance (light years) 26000800 Rotation Period (sec) 4.809 sec 0.089 sec Size of orbit 1.387 x 10 7 km — Flux or brightness (counts/sec) 66.8  1.1 12.6  1.1 Luminosity (ergs/sec) 7.55 x 10 36 9.07 x 10 32 Luminosity compared to the Sun 1970 x L sun 0.24 x L sun

11. Conclusions/ Further Research Astronomical clocks are found in many places in the sky. Astronomical clocks are found in many places in the sky. We studied the light curves of three astronomical clocks and measured their properties. We studied the light curves of three astronomical clocks and measured their properties. We calculated spin periods and confirmed that pulsars spin at very high speeds. They have periods from seconds to milliseconds. We calculated spin periods and confirmed that pulsars spin at very high speeds. They have periods from seconds to milliseconds. Future work: Future work:

12. Acknowledgements … Eberly College Of Science Eberly College Of Science Dr. Daniel Larson, Dean of Eberly College of Science Dr. Daniel Larson, Dean of Eberly College of Science Dr. Mercedes Richards Dr. Mercedes Richards Ms. Jody Markley Ms. Jody Markley Mrs. Annie Holmes Mrs. Annie Holmes Mr. Craig Keiser Mr. Craig Keiser Ms. Joanne Nash Ms. Joanne Nash UBMS Staff UBMS Staff

13. Any Questions?? Any Questions??