Transcript Pulsars: Astronomical Clocks In The Sky

Pulsars:
Astronomical Clocks
In The Sky
Team J:
Ashley Randall
Ashton Butts
Priscilla Garcia
Jessica Wilkinson
Olivia Arrington
Introduction
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Pulsars are rapidly rotating neutron
stars
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A neutron star is only ten kilometers
in size
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They are created in a supernova
explosion near the end of a star’s life
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Pulsars spin at quick speeds ranging
from milliseconds to seconds
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Single pulsars spin about once every
second, and pulsars in binary systems
spin thousands of times every second
Purpose
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To learn how to calculate the rotation period of a pulsar
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To calculate the size of the pulsar’s orbit
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To calculate the luminosity of the pulsar
Methods
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Used NASA observations collected with the Chandra
X-ray telescope
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Used the ds9 computer program to analyze the
observations
Materials
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DS9 computer program written by NASA
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DS9 instruction handbook
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Textbook: Horizons: Exploring the Universe by Michael A. Seeds
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Lecture Notes: Dr. M. Richards
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Chandra X-ray Telescope archives: http://chandra.harvard.edu/
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NASA Chandra Education webpage
http://chandra-ed.harvard.edu/activities.html
Procedures
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Load the light curve data from the Chandra archives
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Light Curve: how light from the pulsar changes with
time
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We measured the period directly from the light curve
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Calculated the average period and standard deviation for the
group.
Procedures
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The power spectrum finds any patterns in the light curve
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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
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When we expand the power spectrum for Cen X-3, the peak
looks broad
Pulsar moving
away from us
Pulsar moving
towards us
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The light from the pulsar is blue-shifted and red-shifted
because the pulsar is moving around another object
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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
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Astronomical clocks are found in many places in the
sky.
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We studied the light curves of three astronomical
clocks and measured their properties.
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We calculated spin periods and confirmed that
pulsars spin at very high speeds. They have periods
from seconds to milliseconds.
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Future work:
Acknowledgements…
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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??