Hi everyone. I'm Brian with the
Scientist in Every Florida School
program and in this edition of Science
Segments I'm excited to connect you to a
scientist to help you learn about
astronomy. What is your name and title?
Hi, my name is John Della Costa. I'm an
astrophysicist and researcher at Florida
Atlantic University.
What do you research and why is that
important?
So I actually study the very centers of
galaxies. We think that at the very
center of every galaxy in the entire
universe there is a supermassive black
hole. These are black holes that weigh
over a million to a billion times the
mass of our own Sun and I studied what
happens when matter actually falls into
those black holes so when a star comes
too close to a black hole supermassive
black hole or a gas cloud or dust cloud
comes too close it starts to spiral in
in what is called an accretion disk. It
forms an accretion disk which kind of
just looks like a big whirlpool falling
into the black hole and as that matter
actually falls into the black hole it
heats up and emits light and I actually
studied the light something from these
accretion discs and that is important
because if we can understand why and how
much light is coming out then we can
better understand the black holes and if
we better understand supermassive black
holes because supermassive black holes
make up the gap the backbone of galaxies
and galaxies make up the backbone of the
universe we can better understand how
black holes formed and therefore how the
rest of the galaxies evolved from the
very beginning to where we are today so
that's why it's important. Can you
briefly describe how people can predict
how the initial mass of a star
determines its evolution? Yeah so I
actually love this question. I'm a pretty
visual person so I brought a few models
belong today with me but basically the
initial mass of a star tells you what's
going to happen to it when it dies when
it when it's at the end of its life
what's going to happen to it so
basically the bigger the star the faster
it will go through its life and these
all of this starred the the slower it
will go through its life so and that is
because it's kind of counterintuitive
because you think a bigger star might
have more fuel to fuel the fusion that's
going on at the core but actually if it
has more mass more fusion is able to
happen in the core so the it's kind of
like a race car or a drag drag car going
down the strip it can it can go really
really quickly and really fast for about
half a second and then it will you can't
drive it any longer or a tiny star it
it's like an electric car it will it can
drive for miles and hundreds of miles
and and you don't even need to refill it
up so that's kind of the difference
between these two I have so let's
imagine that the Sun was the size of
this NASA golf ball here we can compare
all the other stars to our star because
we know it the best we know the Sun that
that's so this star right here is very
very tiny which means it will it will
live for a very very long amount of time
our star is fairly average it will live
for about 10 billion years where this
tiny star will live for over 60 billion
years okay it will live for 60 billion
years and when it dies it will turn into
a planetary nebula because it does not
have enough mass to turn into a
supernova when it explodes that the same
thing will happen to our own star the
Sun when it dies it will turn into a
planetary nebula and it will it doesn't
have enough mass to explode into a
supernova the next biggest star you just
call this tennis ball here this star
will live for about a billion years
it's not much bigger but it will it
lives a lot shorter of a lifetime 1/10th as much this will live for about
a billion years where the next the
biggest stars that we know of like this
basketball here these but these stars
can live they only live for about a
hundred million years and when they die
they turn into a supernova because they
have enough initial mass they turned
your supernova and what will be left
over
instead of planetary nebulae for these
smaller stars there will be a supernova
remnant that will be left over at the
end of its life and at and at the very
center of that supernova remnant there
will be a neutron star
and if we even have like a bigger star
like a beach ball sized star then that
star will actually won't be left over
instead of a neutron star will be a
black hole so these turn into planetary
nebula and white dwarfs be this type of
star turns into a supernova remnant and
a neutron star and the even bigger stars
turn into supernova remnants and black
holes so that's kind of how it all
depends on how much initial mass you
have and that will determine if you'll
die in a really cool explosion or just
kind of let your outer layers in the
star go. Thank you, John and
thank you all so much for watching. We
will see you next time. Thank you.
