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Pulsar Properties Sorting Card Activity (In the Context of giving the SPOT presentation)
Introduction: This activity introduces students to properties of pulsars and the trends and
correlations to be found between properties. We recommend that you do this activity BEFORE
you talk to students in detail about pulsar properties. This activity was developed for use by
undergraduate students who outreach into schools, and give the pulsar SPOT presentation. To
aid them we have created a little script. Feel free to use this script as you see fit.
Script: “During the presentation we talked about how pulsars can help us detect gravitational
waves. Do you remember what a pulsar is? [it is a star that acts like a lighthouse in space; it is
detected on Earth by radio telescopes, etc.]
Pulsars are very interesting stars, and astronomers study study their different properties. I’m
going to hand each of you (or each pair of students) a card that lists the properties of a specific
pulsar. For this activity, this is YOUR pulsar.” [hand out cards]
“Everyone look at your pulsar card. What are some pulsar properties that you see? [get
students to tell you some properties, ex: name, spin period, age, etc.] Let’s talk about some of
these properties, starting with something familiar: Age. That’s how old the pulsar is. And
distance – that makes sense, it’s how far away the pulsar is.
What about spin period? [get student ideas] That’s how fast it spins. And the Change in Spin?
That’s how much the spin rate slows down over time.
What about magnetic field? Pulsars have super strong magnetic fields – generally over 100
Trillion times the strength of your typical refrigerator magnet.
Also, apparent brightness is how bright it appears in the sky. And if it has a companion, that
means there is another star nearby, and that star and the pulsar orbit each other.
Okay, so astronomers collect all this information about pulsars – what can we learn? Good
scientists look for patterns. Let’s see if we can find any patterns in all of this pulsar data.
Let’s try sorting our pulsars by[pick a property— in this example we chose Age]. We’ll have the
youngest pulsars over here (on one side of the room), and we’ll have the oldest pulsars over
here (other side of the room). Work together to put yourselves in order by age of your pulsar.
[give students time and help]
Okay, let’s see if any other properties seem to correlate with age.
[Have the students look for these and discuss amongst themselves, then report out.]
Info for teachers/mentors: You can prompt them through questions : “Raise your hand if your
spin period is less than 1 second. Raise your hand if your spin period is greater than 1 second.
What do we notice? [Get students to volunteer some information] It seems like the older
pulsars spin slower. Does that make sense? Yeah, it makes sense for pulsars to slow down over
time. What about change in spin? The older pulsars are rotating slowly, but are they also
slowing down faster than the younger pulsars? What about the REALLY OLD pulsars
What about magnetic field? What are some magnetic field strengths of the young pulsars? [get
students to tell you]. And what are some magnetic field strengths of the older pulsars? Do you
think there is a correlation between age and magnetic field strength?
Let’s try arranging ourselves by a different property [could let students choose]. How about
spin period? Repeat looking for correlations [again, could ask students to choose]. One
correlation is that really quickly spinning pulsars (i.e. those with very short spin periods), are
more often found with a companion. This has led astronomers to deduce that maybe the
companion star can dump material onto the pulsar and cause it to spin up.
[Continue sorting and searching for correlations] What about distance and apparent
brightness?
Are there properties that are not correlated?”
[Notice that some properties are NOT correlated.]
Conclusion: “So, by tracking pulsar properties and exploring how these properties are or are
not related, we have been able to learn about pulsar properties and deduce information about
how pulsars change over time. “
Follow- up: Have students visit the ATNF catalog and plot pulsar properties against each other
http://www.atnf.csiro.au/research/pulsar/psrcat/
Scroll to the bottom and enter two properties you would like to plot, and then click plot for an
interactive graph: