Pulsars: Astronomical Clocks In The Sky Team J: Ashley Randall Ashton Butts Priscilla Garcia Jessica Wilkinson Olivia Arrington Introduction Pulsars are rapidly rotating neutron stars A neutron star is only ten kilometers in size 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 Single pulsars spin about once every second, and pulsars in binary systems spin thousands of times every second Purpose To learn how to calculate the rotation period of a pulsar To calculate the size of the pulsar’s orbit To calculate the luminosity of the pulsar Methods Used NASA observations collected with the Chandra X-ray telescope Used the ds9 computer program to analyze the observations Materials DS9 computer program written by NASA DS9 instruction handbook Textbook: Horizons: Exploring the Universe by Michael A. Seeds Lecture Notes: Dr. M. Richards Chandra X-ray Telescope archives: http://chandra.harvard.edu/ NASA Chandra Education webpage http://chandra-ed.harvard.edu/activities.html Procedures Load the light curve data from the Chandra archives Light Curve: how light from the pulsar changes with time We measured the period directly from the light curve – Calculated the average period and standard deviation for the group. Procedures The power spectrum finds any patterns in the light curve – We calculated the period from the frequency: Period = 1 . Frequency Results Objects studied: Cen X-3, GK Per, Vela pulsar GK Per Cen X-3 Star size = 10 km Rotation period = 4.807 sec Star size = 6000 km Rotation period = 350.87 sec Results When we expand the power spectrum for Cen X-3, the peak looks broad Pulsar moving away from us Pulsar moving towards us 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 Results Cen X-3 Pulsar Vela Pulsar Size of star (km) 10 10 Distance (light years) 26000 800 Rotation Period (sec) 4.809 sec 0.089 sec Size of orbit 1.387 x 107 km — Flux or brightness (counts/sec) 66.8 1.1 12.6 1.1 Luminosity (ergs/sec) 7.55 x 1036 9.07 x 1032 Luminosity compared to the Sun 1970 x Lsun 0.24 x Lsun Luminosity = 4 distance2 x flux Conclusions/ Further Research Astronomical clocks are found in many places in the sky. 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. Future work: Acknowledgements… Eberly College Of Science Dr. Daniel Larson, Dean of Eberly College of Science Dr. Mercedes Richards Ms. Jody Markley Mrs. Annie Holmes Mr. Craig Keiser Ms. Joanne Nash UBMS Staff Any Questions??