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a pulsar is the crushed core of an exploded star theorists have been trying to understand
the details of how pulsars work ever since they were discovered in 1967
especially how they emit precisely timed pulses at radio to gamma-ray energies now
new computer simulations are providing surprising insights a pulsar contains some of the strongest
magnetic fields known and can spin thousands of times a second that means it's a powerful dynamo
generating an electric field so strong particles are ripped out of the surface and accelerated into space new computer
simulations clearly show these incredible movements for the first time most of these particles are electrons
and their anti-matter counterparts positrons in these simulations their colors get lighter as
they attain higher energies electrons tend to race outward from the magnetic poles
positrons mostly flow out at lower latitudes along a relatively thin structure called the current sheet ultimately
these outflows lead to the formation of a powerful wind that extends far from the pulsar [Music]
magnetic field lines and the particles moving with them sweep back and extend outward as the pulsar spins
their rotational speed rises with greater distance but there's a wall created by the ultimate speed limit
the speed of light astronomers call this the light cylinder
matter can't travel at the speed of light so something has to give before the particles get this far just
before reaching the light cylinder these simulations show that a population of medium energy electrons scatter
wildly sometimes even back toward the pulsar some speed up others slow most eventually
slip past the light cylinder and head out into space the simulations
also show that a small percentage of positrons likely hold the secret to a pulsar's gamma-ray emission some of
these particles become boosted to tremendous energies at points within the current sheet where magnetic field lines meet
these simulations bring scientists one step closer to understanding the incredible physics
of pulsars something that has kept theorists busy for decades
Welcome
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well hello everybody this is scott roberts from explore scientific and this is uh the astronomical league
live segment number seven um and uh i'm uh i'm broadcasting remotely
uh from dallas texas today this is something that i knew i would have to do at one point or another
and um anyways i'm glad uh i could do it with you guys and ever
it's uh i'm we got a great group of people here uh of course
to my left as i see it uh there's terry mann on to my right is barbara harris um
down to the bottom right hand corner is carol orange carol is the president of the astronomical league uh and their
special guest haley wall okay who's going to be giving uh uh this presentation uh that uh terry will
terry mann will uh give the proper introduction for so anyways i'm pleased that you guys are
are watching today and um uh i think that uh you're going to really enjoy this
League Update
terry well thank you scott and thank you everyone for joining us it's a nice friday evening a lot going
on uh carol i am going to ask you to go ahead and get us started with any updates on
the league you might have or anything else you want to talk to us about thank you terry
i bring greetings on behalf of the astronautical league from the mid part of the country where we almost got blown away in the last two
hours but very heavy wind but it's all good the one thing that as we come out of the
pandemic which is so impressive uh we're really getting quite a light show and a show of nature for
example the last two days the annular eclipse many people on the east coast the other parts of the world
were able to see and such impressive images that are being shared the last few days they're
just really impressive so let's sort of a prelude to the two we've got coming up
2023 as well as the next total solar eclipse 2024 that's visible in the united states
thanks again to scott for graciously hosting this it has opened up lots of new possibilities this year for us
uh the virtual end of it and speaking of the virtual part of it uh this year as most of you probably
already know we're having a virtual convention in lieu of our regular
national convention which is called alcon 2021 virtual that makes sense doesn't it
and one of the things we're noticing and thanks terry and chuck allen for co-hosting that uh
co-chairing that event they have got a ton of excellent
speakers already lined up and another thing that's a little different from this at this convention besides being virtual
is that we've reached out to the member clubs and member societies across the country
and see if they would like to be represented and tell us more about their individual clubs and just
tell us what's going on with their clubs and many have graciously stepped forward uh with a door prize
to really put some very nice door prizes out there for the event and we're very appreciative for that
and if there's any clubs representatives who are listening tonight uh which i'm sure there's a ton of them
we would encourage you if you're able to do it as a club if you haven't already contributed feel free to get a hold of terry or
myself and we will tell you more details about it if you'd like to
showcase your club at the outcome virtual this year and the dates for that
event are the 17th 18th and 19th of august
i'm sorry 19th 20th and 21st terry i'll get me in trouble if i put the wrong dates in here and i should be in trouble
so we're going to have a each session we'll have will be each day
will be two sessions and we'll have a break in the middle for
a lunch and that sort of thing and i think everyone's really going to enjoy it so stay tuned on that i think that's about
it oh i want to also give credit to scotland explore scientific
for setting up the logistics electronically of alcon 2021 virtual and it's amazing
you know we thought if we had thought five years ago well we're going to be doing lots of online work uh
and the naysayers would have said oh that can't happen we won't get anybody to tune in well as we have noticed and this another
venue we have a lot more people sharing astronomy than we ever had when we were meeting face to face
so it's really been a good situation for us and i think that's about it terry
is there anything else you would like to add about outcome that's the general idea about that i will probably add more
about alkyne when i get to the questions because i've got a couple slides about but thank you carol you covered
quite a bit of it excellent i won't cover so thank you very much and
what i would like to do is to welcome david levy how are you doing
David Levy
david oh i'm fine sorry to be a little late i lost the link
but i found it no problem thank you for coming how about if you go ahead and restart us
i would really appreciate that okay thanks terry i i want to welcome
you all to the monthly astronomical league meeting and uh i'm going to quote a poem today
that comes from the amateur telescope making i think
it's book one and it's from a poem by c.a olson
it's called a piece of glass and it goes like this he labored late into the night
at early morning his task resumed to fashion best a disc of glass into a subtle curve not
deep but measured only by the shades of white from a simple pinhole made in foil revealing to his
practice eye imperfections infinitesimal until at last his skill produced a curve so
true the mind of men could not destroy the wavering of a breath just a piece of
blast was said but in that simple disc the heavenly host
of suns and stars yeah universes reveal their glory in the sky for us all
to ponder and adore thank you and back to you jerry
thank you david it's always a pleasure to have you here we appreciate it
Alcon Virtual
what i'm going to do now i'm going to share my screen because just as carol was speaking about alcon virtual i'm going to show some
slides and then i'm going to ask the questions for
tonight all right and as carol was speaking
about we have got an amazing amount of speakers here uh if you look down the list it is
amazing everything we've got going on and the speakers can kind of self-define their
selves alcon 2022 will be doing a little talk about what to expect because
i don't know about you guys i'm planning on going to albuquerque next year so it will be in albuquerque new mexico
and i see you laughing carol i'm going to be in albuquerque new mexico in
july of next year we have a virtual tour of the vla now when you look at
that because of the radio frequency they really can't per se do a virtual tour there so what
they're doing is online just like we're doing here they'll be showing things from socorro i believe
from their main office they'll have speakers they'll be presentations it will almost be the same thing as
being there but if you come to alcon 2022 we're going to be going there to visit i
do believe so this will kind of get you an idea of what to expect
and it is an incredible place and then we also have paul cox from slu now he will be giving
a talk during alcon but we are also going to have a global
star party saturday night which will probably start around 11
p.m eastern time and he is going to show some how sloo actually works
and one of the questions we are going to ask everybody is what would you like to see on slough
that night they have telescopes in the southern hemisphere and i have been working with that this is pretty amazing it's a
lot of fun to see what you can image you know the whenever they have it set on the
schedule so paul cox will be talking about that and giving us live views
on the global star party saturday night and if you're interested in being part
of showing live views saturday night please drop me an email at secretary
astro league dot org and we'll talk to you and see what's going
on and put you on a list and i will contact you as it gets closer to see what your cloud conditions are if
you've got some images you would like to show and we do have more speakers that will
be coming on our website is kind of a work in process or prop we're working on it all the time uh
we've put updates on we just updated again last night and we've already got more updates
so it's a constant turnover that we are adding here on the website the next thing i'd really
like you to look at is check out these prizes and check out this grand prize
that will be given away on saturday night that explores scientific has donated it is a gorgeous 127
millimeter mac cast green and this is beautiful
we also have and these are from the clubs i better go back another step carol had mentioned
the clubs have been donating door voices these clubs are incredible we appreciate so much
the individuals and the clubs that have stepped forward to do this as you can see we've got over four
thousand dollars right now in door prizes that have been donated by clubs it is
incredible um so we also have three different pairs of binoculars there's uh overwork
there's explorer scientific there's nikon we have an asir pro we have 10 gift
certificates now think about this these aren't the things that they say spend five hundred dollars will save you
one hundred dollars these are gift certificates they range anywhere from one hundred
dollars to two hundred and fifty dollars per gift certificate
we have a lot of them and we have more to add right now we have an orion 28 millimeter eyepiece
we've got books we'll have manuals we've got sky guides we have books that are coming in now
there's also a discount if you attend alcon 2022 there will be a discount on
the hotel if you would happen to win that door prize but check this out between with
everything going on there's such a variety here and as carol said we have it spaced
so hopefully we'll have at least an hour for a dinner break so we will start and
all of these times are in eastern time we will start at 3 p.m go to somewhere
between 6 7 come back at 8 pm and probably go till about
anywhere between 10 and 10 30 maybe 11 something like that and we will put the
schedule online as we really get it solidified we have
our speakers all confirmed but at the last minute we've had some that say hey
we need to change where we're at so we're swapping out positions on the schedule so we will have that online
shortly but please check out the website it is alcon virtual.org check it out
constantly it does change maybe a couple times a week at this point
and join us as carol said it is august 19th through the 21st and scott roberts will
be broadcasting this for us and again scott thank you for everything you have done you've done
amazing stuff it's it's our pleasure terry thank you we really appreciate it and we
appreciate everybody out there thank you for watching this and please attend
alcon virtual it will be a lot of fun so let's go to the door prizes tonight's
store prize is going to be the astronomical league travel mug there will be three winners
and each of those winners will win one of the mugs now send your answers in as soon as
possible because i will be announcing the winners right after our keynote this isn't like the global star party
where you have to wait till the end of the month this will happen all within this program tonight
and if you are a winner a representative of the league will contact you and please send your
answers to secretary astro league.org
and here we go first question name the largest known star in the night
sky and send your answers in quick
next question how much does or did a full nasa space suit cost
and the last question how many light years away is sirius the brightest star in the
night sky and that is the three questions please
send your answers to secretary at astroleague.org
thank you and i will go back next up is a very good friend of mine
and she has been she's worked on a project that i've never heard about before her name is barbara harris
Barbara J
she is a retired ob gyn physician and she has her own observatory called
the bar j observatory in central florida and she's had an interest in astronomy since high
school she got her first ccd camera in 1999
and wanted to dedicate most of her imaging to science she's been a long time member
of the double a bso and doing variable star photometry
so barbara i'm going to let you explain exactly what this is that you've done and how
you've done it because i think it's really pretty cool okay thank you terry i'm going to go
ahead and share my screen and basically what terry's talking about is a little project that i started
eight years ago um the project is
um a project concerning barnard star
uh barnard star um as many of you know is a
um a star in the constellation ophiuchus it's a red dwarf star six light years
away in fact it's considered the fourth closest star to our solar system like i said it's a
variable star which is how it came to my attention because i monitor
variable star brightness uh its brightness hangs around 9.6
magnitude in 1916 ee bernard measured its proper motion at
10.3 arc seconds a year and this makes it the
highest proper motion star uh relative uh to the sun
so i started monitoring it and decided that at 10.3 arc seconds a
year that with my setup it would move about seven pixels per year and i thought that
that would be easily demonstrated so every year around the beginning of uh
june i take an image of bernard starr mainly to do photometry
but i save these images and every year i sum up the images so that i can see the movement of uh
barnard star and uh this is my latest image uh i i did my latest uh
image around a week ago and as you can see there are eight little
stars here between 2014 and 2021 and each of those represents the
position of barnard star uh every year between 2014 and 2021.
and i thought it was a neat little project to do uh to demonstrate that that there is
activity in our our so our skies uh the stars aren't stationary it proves that that
they're not just sitting there that there is proper motion uh among the stars and most of the stars
um the proper motion is so small that we won't see movement in our lifetime but
barnard star is has such a large proper motion that you could in one year you're able
to detect movement uh of that star and uh besides detecting the movement i also
monitor it on a regular basis uh for its brightness uh
it it like i said it is a variable star and it has been shown to have at least
um one uh extrasolar planet so there is at least one planet uh
revolving around uh barnard star so it's an interesting star
um not just for its uh large proper motion but also because
there are at least one planet maybe more orbiting it so this was uh
is one of my favorite projects that i i like to do is to monitor barnard star and demonstrate its proper
motion every year
and i think you know i think that's what amazed me the most was i never really thought of seeing that we
would see a star move in our lifetime and i was not aware of this and until you talked to me about it she
showed that picture and i said what am i looking at that's that's really different so i think that's an amazing project
every year i kind of look forward to seeing bart's picture how the star has moved so thank you
barbara i appreciate that very much you're welcome i could just say just
something briefly terry we often hear that the north pole at some point the pole star will change
and yet barbara was able to show that demonstrate that there's more theoretical what we've been
hearing about the the polaris the north star uh so it's uh uh so it's interesting to see that you've
really demonstrated that barbara thank you it is pretty cool
so for now i would like to go to our keynote speaker her name is haley wall she is a physics
ph.d candidate at west virginia university studying pulsars
which are dense spinning neutron stars her work focuses on polarization or how
light from a pulsar gets twisted as it goes through space she works with nano grav
collaboration a team working on detecting gravity gravitational waves with pulsars
haley is very passionate about her science communication and in her spare time she enjoys baking
writing and doing jigsaw puzzles so now haley is going to take us on a journey
through the exotic world of pulsars so thank you very much haley i'm looking
forward to this thank you so much for the introduction terry and for having me tonight i'm
really excited to tell you about one of my favorite objects i've been studying them for eight years and
they still fascinate me so let me share my screen
all right
great so today i'm going to be telling you about pulsars they are these dense spinning
neutron stars and i'm going to be taking you on a journey everything from the discovery of the first pulsar
to weird emission properties of pulsars to how pulsars are used to do different
types of science so how many of you are familiar with
this anybody has anybody seen this
yes thank you so this is the the cover of the i think
it's 1979 joy division album and what you may not know about this cover
is that each of these little blips these these little bumps is emission from
a dense spinning neutron star each one of these is a single pulse from a pulsar so i see
this everywhere i was in las vegas a couple weeks ago for a wedding and somebody walked by with this on a t-shirt and i almost
stopped to take a picture but i didn't um but it's yeah it's
something in pop culture that not many people know is kind of an astronomical phenomenon
What is a Pulsar
so what is a pulsar a pulsar is a super dense magnetized neutron star that spins
at incredible speeds and i'll go through exactly how how dense in a minute it emits radio waves and
its light flashes past earth like a lighthouse and so its magnetic axis is offset from its
rotation axis and it emits a long expanded magnetic axis and so it wobbles
and passes us like a lighthouse pulsars are also incredibly precise
objects some of the fastest spinning pulsars which are called millisecond pulsars which i'll get into
rival atomic clocks in terms of how precise their pulses are so they're very very
regular so how extreme are these objects
so i mentioned that they're dense how dense a teaspoon would weigh as much as mount
everest and a thimbleful would weigh as much as earth's entire population
so in terms of density it's like taking something the mass of the sun which is 99.99
the mass of our solar system crushing it into the size of manhattan or just a small city so that's how dense
it is i mentioned they're magnetized how magnetic
they are a hundred million times earth's magnetic field so the magnetic field of the earth
or a magnetic field of a pulsar is about 10 to the 12th gauss whereas the earth's
magnetic field is about half a gauss at the distance of the moon a pulsar
would wipe out all of the data on all of the credit cards on earth don't worry the closest pulsar
is about 400 light years away but still these things are really crazy
and how fast do they spin about as fast as your kitchen blender uh so up to about 700
times per second so i'm just trying to okay
so i'm going to hopefully this will work have you listened to a pulsar
so if you look at the pulsar names they're basically their names are like
their phone numbers and so this just denotes the right ascension and the declination
of a pulsar and if some have b's some have j's b just means they were discovered before
1993 and jay denotes that they were discovered after 1993.
so i'm going to play you a pulsar sound so this is pulsar b0329
can you all hear that yeah it came through loud and clear okay
thank you okay so each little blip
is the sound of a pulse sorry so that that sorry for the
background noise um so that's one pulsar this is the crab pulsar which i'll get into a little bit later it spins a bit faster about 30
times a second so you can hear that you can barely make
out single rotations and then here's pulsar b1937 it's a
millisecond pulsar which is a different type again which i'll get into in a second and take a listen at this one
you can barely you can't even pick out individual rotations it spins almost 700
times a second i'm gonna put my headphones back on
really quick
so that's just to give you an idea of exactly how fast the pulsar spins they are they spin really really fast
Fun Pulsar Facts
so a couple other fun facts about pulsars uh their surface gravity is about a hundred billion times that of
earth so if you had a cat that weighed say 10 pounds on earth
it would weigh a trillion tons or so if you had a cat away 10 pounds on earth it would weigh a trillion pounds
on the surface of a pulsar that is a very fat cat the first planet outside our solar
system was actually found around a pulsar that's not something a lot of people know uh but that's just kind of one of my fun pulsar
facts that i like to share so how do we happen upon these crazy
The First Pulsar
neutron stars so in 1967 jocelyn bell a graduate student at
cambridge was built this homemade radio telescope and she wanted to search for quasars
so quasars what we now they're what we now know as these active galactic nuclei and so they're just
giant black holes eating tons of matter that shine really bright and so she was looking for the
scintillation of quasars and so what she would do every day is take data with her homemade
radio telescope and go through hundreds of feet a day of basically graph paper looking for
signals and so she happened upon a signal that was very periodic and
occurred about once every 1.33 seconds and so it was really precise
she had no idea what it was so she went to her advisor dr and anthony hughish and they tried to
figure it out together so they looked to see if it was television signals some kind of phone
signals if it was the corner of buildings and they couldn't find anything but they
figured out that it was moving with the stars and so it would come a little bit later every day
as the stars change so that kind of gave them a hint that it was extraterrestrial
and so they nicknamed the first pulsar lgm1 standing for little green man one
The Discovery
so that was in 1967 they published their discoveries in the journal nature which is a very
prestigious journal and they thought it was the result of oscillations of white dwarfs or
neutron stars and neutron stars had been predicted about 35 years earlier so
they kind of had an idea but didn't really know so later that year franco pacini
postulated that neutron stars could emit a beam of light that could be detected and in 1968 thomas gold put two and two
together and figured out the pulsars were these neutron stars that were emitting these beams of light
so the puzzle had been solved so in 1974 a nobel prize was given
for the discovery of pulsars to bell's advisor anthony hughish
and people like to call this the nobel prize because it was jocelyn bell who unfortunately did not get the nobel
prize that year but she did win another prize so in 2018 she was awarded the
Breakthrough Prize
breakthrough prize a three million dollar physics prize for the discovery of pulsars and she
actually used this money to help establish scholarships for underrepresented groups in science so i really like this headline it's very
sassy scientists wins three million dollar physics prize 44 years after a man
won the nobel for her discovery and when asked about this ask when asked about if she was upset
about not winning the nobel prize her answer was that astronomy had never been given at you
know any astronomical discovery had never been given a nobel present physics before and this really paved the
way for astronomers to to win this prize and so she's an incredibly humble person and
just really kind i got the chance to meet her she came to wvu a couple
a couple years ago and she's just an incredible person
Types of Pulsar
so there are a couple of different types of pulsars there are canonical pulsars which are
the regular or some people call them slow pulsars they though it's hard to think of a
pulse or a slow uh that rotate every couple of seconds so they can
they have periods of a half a second to about 20 seconds and then you have the millisecond
pulsars which spin more than 250 times per second so these are the really good um the
really precise ones there are a couple of pulsar like objects and pulses are like phenomena
Pulsar Objects
there are magnetars which have the strongest magnetic fields in the universe which are a thousand times greater than
a pulsar's and so those are very strange objects we know of a whole bunch of them
and there are rotating radio transits which are very sporadic pulsars they
emit very they do not emit very frequently their kind of peekaboo pulsars
was the the name that the discoverer gave to them
um and then there are frbs which are fast radio bursts which aren't an object
we're not quite sure where they come from yet but they are very very very bright radio
pulses that kind of look just just like an extreme pulsar pulse we think they're from
magnetars there was actually a paper released yesterday that catalogued 500 of these
fast radio bursts and tried to figure out where they came from and it's a very very vibrant
field of research right now uh the discovery of the discoverer of them uh duncan lorimer
is actually at west virginia as is the discovery of rotating radio transients uh which is mclaughlin who i work
with and so it's um western virginia is a very cool place to be
How Do Pulsars Form
so how do pulsars form so they form essentially form when a massive star runs out of fuel
and so when a star is born basically what happens is that you get this giant dust cloud
that starts to collapse and when there's enough pressure nuclear fusion will ignite
and so you have this pressure of gravity going inward and when this nuclear fusion kicks on it
releases energy by combining atomic nuclei so for instance hydrogen hydrogen into
helium and so that creates an outward pressure that balances the gravitational pressure
inward and balances the star so that it can keep fusing and keep living its life as a
star when iron is formed in the core of massive stars the energy that it takes to make iron is
greater than the amount that it outputs and so it's consuming energy in the core so it can no longer balance the gravity
that's pushing inward and so it begins to collapse and so all of that matter collapses inward and there's a giant
explosion that bounces off the core and it basically explodes
so what's left inside is a neutron star if it's a certain mass it can also be a
black hole if it's a greater mass but if it has the correct if it's
spinning and if it has a certain magnetic field then it will turn on and emit radio waves and become a pulsar
millisecond pulsars
millisecond pulsars are a little bit different so as pulsars emit energy in the form of
radio waves they eventually slow down and they
their rotation slows down over time and sometimes it can stop sometimes it can just slow and
the pulsar enters the pulsar graveyard and so it's basically no longer spinning but if
it has a companion which a lot of stars in the universe do then it will accrete matter off of that companion
and spin up the star and make it spin faster and faster so this is very much like an ice skater
who pulls their arms in and gets faster to conserve angular momentum and so this will form a millisecond
pulsar and this is what makes it spin very very fast and these are the pulsars that are really precise
clocks so what are pulsars made out of i
what are pulsars
actually explored this a little bit today and found out some some very neat stuff so pulsars are
neutron stars they are so dense that the atomic nuclei
are actually crushed down the protons and the electrons combine and
it's there's incredible pressure in it we don't quite know what is at the core but we do know that it has a very thin
atmosphere it's about one to two centimeters thick which is seems small but if you think it i mean
the pulse are a city size so it has an atmosphere a very thin crust it has an outer crust
uh and an inner crust and kind of what's in the middle here we're not quite sure of but one idea is that it's this weird
stuff called nuclear pasta and so what happens is that the
the atomic nuclei so the protons the neutrons get like stretched and squeezed and so
they get to this point where they look like gnocchi or spaghetti and they just form this weird
lattice and as you go deeper you get you turn from gnocchi to spaghetti to lasagna
then you eventually get like anti-spaghetti and anti-gnocchi i was researching this today and was
very hungry by the end of my my research but i we think that's right what's happening there we're not quite
sure what's at the center but this involves the equation of state of a neutron star
and just trying to figure out what's going on inside and there are ways that that we can probe that and i'll talk
about that a little bit later so how do we observe pulsars how do we
how to observe pulsars
observe these uh these radio waves so again pulsars give off radio emission
which have a very long wavelength and so we need a big dish to capture them
so we observe with big radio telescopes this is the arizo telescope in puerto rico
rest in peace arecibo it is unfortunately no longer with us and then we have the green bank
telescope actually here in west virginia that is the largest steerable radio telescope on the planet
pulsar telescopes
so pulsars are a worldwide thing and we have telescopes all around the
planet we have the fast telescope in china that's a the world's largest single dish
radio telescope we have the the lava telescope
in england we have the meerkat telescope in south africa we have the giant meter wave radio
telescope in india this is the park's telescope in australia and we have the very large array in new
mexico so as you can see pulsary telescopes don't all look the same radio telescopes can look very
different from a couple from an array to a big dish there are different ways
of observing pulsars so i wanted to touch on pulsar emission a little bit
pulsar emission
i'm really glad that the video talked about kind of what's going on with the emission because that's not something i actually cover so you got a kind of a
little taste of that so when looking at a pulsar each pulsar
is different in terms of its emission and so how we look at pulsars is to we
look at the pulsar beams and so the as a pulsar goes by we'll see if we
graph the energy of a pulse around this y-axis of the yellow and time on the x-axis
we can see that the energy of this pulsar basically
when the pulsar comes toward us and so we make this average profile which maps the energy over time
of this pulsar and so individual pulses may vary but over time this average
pulse profile is very very stable so pulsar emission can look a little bit
different based on what kind of pulsar you have this is one of the leading theories
for regular pulsars millisecond pulsars are very complicated
everything kind of goes crazy when you have this accretion process with
the magnetic field so this is just for normal pulsars so pulsar average profiles like you saw
can have different number of components based on how we see them so the
the theory is that this emission cone is made up of three different regions the core
the inner cone and the outer cone and so where our sight line crosses determines how many of these components
we see we don't know if all pulsars have all of these components but we think this is a
general structure so for instance if we cross through
all of the components we can have up to five components in the average profile and so you go through the outer cone
then enter then core then enter again and then outer and so you make a shape like this sometimes you only go through four of
them sometimes you only go through the two cones and so you can have four emission components sometimes you'll
only hit three sometimes it'll just be an inner cone core or inner cone
again we're not sure if all pulsars have all of these components but we think that that most of them do so
pulsar nulling
pulsars do very strange things that's one of my favorite parts about studying pulsars is that
there are a lot of things that we're not quite sure about yet and so that keeps things interesting one weird pulsar phenomenon
is nulling and so nulli is essentially when a pulsar turns off and doesn't emit so you can
see that this looks a lot like the joy division album cover but you can see this kind of
gray spot where you don't see any of these and so that's when a pulsar nulls it just doesn't emit so this could be caused by
something intrinsic within the pulsar or the magnetosphere or it could be just geometric or the pulsar is for some
reason turning away from us we just don't see anything so we're not quite sure but by getting a larger sample of nulling
pulsars we can we can try to figure that out so we're working on that
pulsar mode changing
so another thing that can happen is mode changing so i mentioned the emission pattern of a pulsar
and sometimes that can change so most of the time this pulsar for
instance can be in the red so when you when you observe it with a big radio telescope you'll see
this average profile but other times when you see it it'll look like the black profile so
this component grew a little bit this one stayed the same but this one grew a lot and so this along with nulling can be
periodic or it can kind of happen randomly we're not quite sure it can be different for different pulsars
sometimes this can happen for a couple of pulses every once in a while we're not quite sure this could be due
to magnetospheric effects something there's a lot of plasma and charges going on there or
some something with the inner neutron star so something maybe something with the nuclear pasta
pulsar swishing
so another really strange phenomenon that i'll just touch on is pulsar swishing so this is something
that i studied for four years in undergrad and i find very fascinating
so if you make so this is not an average profile but it's looking at the longitude of the emission
of the pulsar of the pulse and so you'll see this is just centered and so it
basically what what it means that this that this is straight is that it's being emitted from the same
spot on the pulsar but if you look over here it suddenly changes and comes from a different place
in the pulsar we're not quite sure why this has only happened in two different stars so this
is one of the stars this is the other it happens very very frequently in this star and
it can have different shapes it can go for different lengths there seem to be no pattern to this
there was a paper done a couple of years ago that looked at these swishes at different frequencies
so as you go to higher and higher frequencies you go closer to the star but lower frequencies you're farther
away from the star so if you look at these with high and low frequencies simultaneously
then when a swish happens at high frequencies a null happens at low frequencies which
really added to the puzzle which is very strange we think that they could either be due to a binary companion
or some kind of magneto effect and not quite sure if it was a binary
companion it would have to go around the star very very quickly so we're not quite sure that's still
something that we would hopefully like to to figure out
first exoplanet
so pulsars do cool things but there are also some very interesting pulsars themselves i'm just checking on the chat
to make sure there are no questions okay um so i mentioned that the first
exoplanet sorry i have a cat visitor um the first exoplanet was found around a pulsar it was around this pulsar b1257
it was discovered by dale frail and alexander bolson in the 1990s and actually two planets
one's three times earth mass and one is four times earth's mass and it's a crazy system we
don't know if there are we don't think that life could survive around tulsa planets we only know of a couple of
systems like this but this was the first one if anybody ever mentions exoplanets to you
pull this fact out of your back pocket another really interesting pulsar is the
Crab pulsar
crab pulsar so you've probably seen this gorgeous hubble image of the crab nebula so during the day once
in in china chinese astronomers looked up at the sky and basically said hey what's that because
there was something that basically exploded and was bright during the day and so
astr so astronomers and historians have tracked this back to the supernova of that
created this crab nebula and so you can see this really gorgeous
glowing nebula that has all of these different elements in it and it's lit up
but the thing that's lighting it up is this pulsar in the middle of it it's radiating energy and causing it to
glow and so this is one i think this is one of the pulsars that we can see in an optical
but this is the source of the energy of the pulsar so another kind of cool type of pulsar
Spider pulsar
is the are these spidery neutron stars if you know anything about spiders you've probably heard of a black widow
black widow's mate and then the female eater companion and we've kind of brought that into the
pulsar realm so black widow pulsars are in binary systems and they
their emission goes straight toward their companion and they basically obligate their companion with their radiation
uh there are also red back pulsars which are black widows but with a higher mass companion so i don't know if they totally oblite them
but we know that millisecond pulsars need to need to accrete from somewhere to spin
up and we think that these black widow pulsars could be the cause of some isolated
millisecond pulsars that we have so another really interesting system
Diamond pulsar
that i that i like is this diamond planet i don't know if you know this but about 400 light years
away there's a thousand carat diamond just hanging out in the sky uh that's about four times the size of
earth so there is this crazy planet that's the core of a white dwarf orbiting around
uh pulsar 1719 and it's possibly the core of a white dwarf
there are carbon white dwarfs and so if a pulsar is radiation
uh kind of obligates a lot of material what's left is the core of a white dwarf that happens to be compressed into a diamond
yeah again it's 400 light years away so we probably don't want to don't want to go there
Double pulsar
there's also this double pulsar system that's really interesting it's the only system of its kind and so you have these
two pulsars that are just beaming away and just going around each
other and so this is as you can imagine it's kind of a crazy system of crazy dynamics because you
have these really heavy neutron stars that are just orbiting each other and this actually won a nobel prize for
the prediction of gravitational waves coming from this is so much all which i'll touch on a little bit later
so one of my favorite pulsar effects of all time is this system that involves a pulsar and a
white dwarf companion so this companion orbits this pulsar
at a radius of about six hundred thousand kilometers so about twice the distance of the moon and the difference between the
semi-major axis and the semi-minor axis so you know call the semi-major this and the semi-minor this
is 3.7 microns which is 1 20th the width of a human hair so this is the
most astronomically perfect circle this is so the closest pulsar is about 400 light years away
so from hundreds of light years away we can tell that we can measure this perfect circle
and so this is the crit this is how precise pulsar timing is which i'll get into in a second
but this is 1 20th of a human hair what yeah exactly
so for those of you who aren't very familiar with space-time i'm going to get into a little bit of it so i just wanted to
give you a kind of a quick overview so back in newton's time gravity was
thought of as this invisible force that held objects together and held the planets around the sun
but einstein came along at the beginning of the of the 20th century and said hey that's
there is some kind of force here and it's this fabric of space time and so it's this 3d i guess 40 with time
but fabric but it's really easy to it's much easier for us to think of it in terms of
2d so like a 2d sheet and so what's going to happen is the way i like to think of it is
matter tells space time how to curve space time tells matter how to move and
so you get these really massive objects that create this dip in space-time
and then the space-time will tell the matter how to move so this is for instance the sun and the earth and
so if you have a really massive object and a much smaller object it'll go around so this is
exactly like what's going to happen if you've ever put a penny into one of those like big well things
at the mall it just goes around because that's the orbit that it follows and that's the the least energetic uh configuration and
so this is this is what's going to happen and so this curving of the fabric of space-time
causes gravity and it causes gravitational interactions and so as you can probably tell pulsars
are really really heavy and create a very deep well on the fabric of space time and so there's a lot that that we can do
with that so one concept that i've mentioned a couple times that i just want to introduce formally now
is pulsar timing and this is kind of exactly what it sounds like it's getting
the times of a pulsar and so millisecond pulsars are really stable we can predict
exactly when the light will get to us down to like i think it's like eight decimal places
it's it's nuts it's so precise and so we can study these types of arrival and
get a lot of information from them for instance we can use pulsars to
measure the mass of neutron stars so we can use this pulsar timing technique so this is
also the way that the first planet around a pulsar was discovered so as the pulsar and
the planet or in this case a companion move around the center of mass so
if you haven't taken a physics class recently then a center of mass is basically where there's kind of equal
mass on both sides so if you've ever tried to like put a broom on your finger then you're going to move it to the place where the center of mass is and
that's where it's balanced and so the same is true in in systems like this you're going to have basically the mass
orbiting around the center point and so like in the solar system the sun
will the sun actually orbits the center of mass even though it's basically within the sun but anyway you're going
to have the center of mass that both of these things are going to orbit around and so if we can get the times of
arrival of a pulsar very precisely what that's going to show us is when it's over here when it's at the
farthest point it's going to be a little bit farther from us and so the pulses are going to arrive
slightly later but if it's coming toward us well we can see a doppler shift in the pulses but also
it's going to come to us a little bit earlier and so by looking at that and by timing this pulsar
we can measure the amount of mass in the system eventually figure out the radius and do
all kinds of crazy things with gravity and figure out the mass of this neutron star
we can also use it to test einstein's theories so there's another crazy system called
the triple system where you have a pulsar this is it's it's dip in the fabric of space-time and you have these two white
dwarf companions and so we can track the light of the pulsar and time the pulsar to figure out how the
system is moving and so by doing that it can tell you about the gravity of the stars the amount of
essentially the the dip and space time that it creates and it can tell you a lot of things
about the system uh again einstein's theory zero kind of about space time
uh the major one and so we can test the strong equivalent principle which has to do
with gravity by looking at this pulsar system by using the times of arrival of these pulses and everything checks out don't worry
einstein has been proved wrong at least yet but everything checks out and so this is one of the strongest tests of the strong
equivalence principle so we can also use pulsars as
gravitational wave detectors so when massive objects are orbiting
around each other and when they get closer they lose energy and so that energy has to go somewhere
and so it's radiated out into the fabric of space-time and creates these ripples they're actually very very small this is
just exaggerated to show you but they will create these ripples just as the system loses energy
and so these gravitational waves can come from black holes two black holes orbiting
each other two neutron stars a black hole and a neutron star so a lot
of massive objects so you're probably thinking okay why do we need pulsars
ligo has discovered a ton of sources of gravitational waves so why why isn't that you know why isn't
that good enough so ligo can only detect gravitational waves from different sources so the way i like to
think of this is like the electromagnetic spectrum so you have different frequencies of light
you have radio waves you have x-rays you have gamma rays and you have all these different types
of light and you need different instruments to measure these so you have different sources of radio
waves some stellar objects you have really energetic bursts that are cert
sources of gamma rays and for instance you wouldn't use an optical telescope
to look for gamma rays because that's just it's the wrong frequency it's not you know the correct frequency
so you wouldn't you know use a radio telescope to look for or you wouldn't use a gamma-ray
telescope to look for the glow of infrared because it's just it's not built that way and the exact
same thing is true with gravitational waves so gravitational waves come at different frequencies
on this plot you see frequency and that's just the frequency of the gravitational waves
and h is the strain of the gravitational waves which is basically how much
the space time is stretched and squeezed as the gravitational wave comes along
so ground-based interferometers like ligo will only be sensitive can only see these
high really high frequency gravitational waves that are created from things like neutron star mergers and black hole
mergers but to look for gravitational waves from stellar mass compact binaries and
supermassive black hole mergers you need a space-based instrument like
lisa which is going up in the 2030s which is basically ligo in space
but if you want to look for the gravitational waves from super massive black hole binaries and
mergers and try to detect primordial gravitational waves which are just gravitational waves from
the the energy of the big bang you need pulser timing arrays and so if you want to learn about the population of
supermassive black hole mergers uh then you need these pulsar time areas to detect that
and you also have the cosmic microwave background which is light left over from the big bang and those can also be used to detect
primordial gravitational waves but we'll focus in on the timing rays for now
so the pulsars so there's a way that we can that we will know if a gravitational
wave passes between us and a star and the way that we know that is by creating what's called a hellings
and downs curve and so it might be a little bit small but plotted on this x-axis
is the angle between pulsars in the sky so for instance this angle or this angle
and so it's the angle between any two pulsars and this is the arrival time correlation it's just a factor that's
calculated from the times of arrival and so by looking at different pairs of pulsars
on the sky and by looking at their arrival times we can plot them and so if you plot a ton of pulsar pairs
on this this helens and downs curve then what you'll get is you will definitely
know that there is a signature of gravitational waves and that is is actually not as easy
as as it may seem um this takes a lot of data i work in
nanograv which is the north american nanohertz observatory for gravitational waves
it's just a north american branch that's trying to detect these and we're on our 15-year data set and so we
have 15 years of pulsar data we monitor pulsars every couple weeks
we have tons of times of arrival and we're still really trying to do this it takes
a lot of computational power a lot of people a lot of years of data in order to do this and this is a
giant operation that involves a lot of people and a lot of international collaborations actually so you have the
international pulsar tiny array which is a timing array from with people from all over the world
so you have nanograv which is in north america so we use arecibo green bank
uh the very large array in new mexico and the new chime telescope in canada to monitor pulsars
chime can actually time a couple of at times tons of pulsars every day and it's going to be very very
valuable you also have the european pulsar timing array which uses effelsburg in germany the sardinia radio
telescope in italy westerborg in the netherlands not say in
france and laval and the uk to monitor pulsars you also have the meerkat telescope in south africa that's
part of the south african pulsar tiny array you have the udi radio telescope and the
giant meter wave radio telescope in india so it's part of the indian pulsar timing array that's fairly new
you have fast which is the um which is the giant telescope in china that's doing work
and then you have the the parks telescope and a couple of other smaller telescopes
in australia that are working toward this and so by working with these international collaborations and
combining data which is a very very complicated process you can search for gravitational waves
and again by doing there's a lot of computational power involved a lot of data and data combination is really tough but
we're all working together to try to detect gravitational waves
so have we found anything yet uh maybe if anybody was at the american
astronomical society meeting in january there was a press conference about this we we might have discovered
gravitational waves not quite sure there's a possibility but we have some kind of strong signal
but we can't rule out all sources of noise so there might be some kind of thing in the
in space that's causing some kind of weird signal we definitely don't have a hellings and downs curve yet so we
definitely don't have pulsars on this curve but there there's something in that data so so
we'll have to see so what's the future of pulsars we
a new telescopes are coming on board all the time the chime telescope is a very powerful
new instrument and we're starting to time pulsars with fast and we really want to probe a neutron
star's interior using pulsar timing the nicer team the neutron star interior
composition experiment is is working on that try to get better measurements of the mass so we can ultimately figure out
exactly what is inside a pulsar and we would love to detect gravitational waves using pulser timing
so it's a possibility so can you get involved in pulsar work absolutely so one way to get involved in
pulsar work if you are either a student or a teacher
is through the pulsar search collaboratory and it allows high school students and teachers to look at real pulsar data just looking at plots like
this to try to detect pulsars and to try to search through a ton of data that we have so if you're
interested i can paste this in the chat and we can share it and that's how you can
you can get involved and yeah lots of pulsars have discovered been discovered by students so so thank you so much
and i will take any questions that you have um if you're on twitter feel free to follow me i do this
pulsar friday where i talk about a new pulsar topic every week so i will leave it at that and again
thank you so much for the invitation thank you that is amazing
oh i don't even know where to start can i ask a quick question you ask all
you want um haley um you said that
uh pulsars originate from massive uh stars so what differentiates
a star from whether it goes to a rotating neutron star versus a
black hole are our neutrons uh are pulsars precursors for black holes
so we're not quite sure if neutron stars are the precursor black holes um some neutron stars can
combine they might become a black hole but it's just the mass of the star so it depends on how much mass is in its core
and if it has a ton of mass just the basically the most massive a lot of mass
then it will collapse and it will have so much gravity that just everything will collapse and nothing
will be able to get out and so the answer to your question is that it depends on the mass of the star
does anybody else have any questions i'm i'm just you know dumbfounded by
you know the i mean really the truly exotic nature of these pulsars you know and and uh
it's just it's kind of a mind-bending just to think of of um you know
how extreme you know matter can become you know and so it's it's uh i find it
very intriguing and uh i would love to um you know
uh follow haley in her you know her broadcasts and stuff as she does
those are you doing them every friday uh basically every friday so i also
i'm starting to alternate between different topics and so once every friday i'll have a thread on
various pulsar topics i did the discovery of pulsars once um
how we can use pulsars to navigate with spacecrafts once i also have a blog that i do that
combines baking and pulsars which you wouldn't think combine but i like the great british
bake off and so i'll bake something from there and then turn it into a pulsar and then talk about pulsar science
so i also tweet those that's also a form of outreach that i do if you like baking you might want to
follow me but um yeah so every every friday will there will be something for pulsar friday
and i just found overall the way you describe them you know the uh they're just beautiful you know
strange and beautiful that's all i can say haley how did you become interested in pulsars just
curious so i went to the university of vermont for my undergrad it was kind of like a last minute add-on
school and i didn't go there for astronomy but i had done astronomy research in undergrad
and in high school a little bit i just did a tiny bit i went to a university like once every
week and just did a little bit of stuff but i found it fascinating and so i love the whole process with research and so i
came in and just just wanted to do research and so at the university of vermont the physics department is not big there
was only one astronomer at the time doing research and she happened to be doing pulsars and so i said i have no idea what a pulsar
is i haven't heard of them but i want to do research and so i jumped on the pulsar
train and haven't gotten off since i went to graduate school with the intention of studying pulsars
because they fascinate me every day and i just no matter how much i study them they're still fascinating well you certainly
come very far you're extremely knowledgeable thank you definitely you know what
really brings it kind of home to me and and this is probably minor but i'm one of those people that i learn best
when i can actually do something myself or hear something myself and when she played
the paul the sound of the pulsars i mean we we all know pulsars then that when
you can actually listen to different pulsars at different speeds
i mean for me that was really amazing to hear that because again you're talking motion
what's happening out there and that just really kind of blew me away i really enjoyed that so glad
yeah and hallie what time is your broadcast on twitter on friday uh i do them usually there'll be a
thread and so they're always up and so usually in the afternoons on friday eastern time sometimes in the
morning usually in the afternoons but again they're always up so you can go and just search for that
hashtag and you'll find them all but it's a really good way for me to to do a lot of pulsar outreach and to teach
people about pulsars because it's kind of a niche subject and not a lot of people know about them
but i i love sharing my enthusiasm for pulsars through that you did a great job that was an amazing
talk i really enjoyed that and one thing i do want to point out is jocelyn bell burnell
is speaking at alcon virtual her talk will be on saturday
august 21st at 3 15 p.m eastern daylight time so please
tune in for that i i can't wait i've never met her i can't wait to hear her speak
she she's got to be one of just amazing one of our many amazing speakers she is
phenomenal oh i bet i bet so so are there any more questions
all right hallie thank you so much that i really enjoyed that thank you so much me
oh anytime you're welcome anytime so um if there we go i'm gonna go ahead
and share my screen and go back to the questions
see where i left off oh yeah i went back up to check um what time jocelyn bell burnell was
speaking so um let's go back
there's the questions okay here's the answers um and i need to move everything out of
the way the largest known star in the night sky
is you y scooty the star is sought to be 1700 times the size of the sun
now it used to be they thought that vy canis majors was the largest star in the
sky it's kind of hard to be exact with something like this but anyway
the winner is josh novak and how much does a full nasa space suit
cost well it was 12 million at one time and 70 of that cost was for the backpack
and control module but that was in 1974. if you price these
today they would be an estimated 150 million dollars
yeah and andrew corkill is the winner on that question
the last question how many light years away is serious the brightest star in the night sky
and 8.6 light years away and the winner is israel monterosso so
thank you israel now somebody a representative of the league will contact the three winners
and get their information and we would like to invite you back for
astronomical league live eight which will be on july 9th
at 7 pm and you will join us right here awesome yeah and thank you
so does anybody else have any closing remarks you would like to make another outstanding uh
session of speakers and well done tyrion setting this up and scott you are welcome i was so
fortunate to have hallie come on i i am just amazed at that talk
i really have to let all that sink in because you know i know about pulsars but as hallie said a lot of people don't
know that much about pulsars and that information was easy to understand for me i mean as
easy as it could be for me to understand um and i just really enjoyed that talk hallie thank
you so much i know i just uh followed her on twitter because i'm fascinated by pulsar
definitely well everybody if there's nothing else i would like to thank each
one of you for being on here david levy thank you always good to see you
thank you thank you so much terry and i'm sorry i i had to be i was late today
but i was here and thoroughly enjoyed haley's talk yes and this entire meeting i look forward to
seeing you in july we look forward to having you here and no worries about being late that's not a
problem at all we're just glad you're here thank you and carol thank you thank you for
letting giving us some updates on everything going on barbara harris a pleasure as always
you're welcome we'll be talking to you and scott thank you again you have done so much
and we are really looking forward to july's uh alcon virtual and to
astronomical league live on july 9th so thank you all for being here and
thank you again to all the clubs all the people that have done donations and thank you to everybody listening we
really appreciate you being there all right that's awesome thank you terry good night everybody
good night good night good night bye bye bye
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