Download 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

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
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Lecture Notes: Dr. M. Richards
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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…
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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??