Greetings and welcome to the
Introduction to Astronomy.
One of the things
that I like to do
in each of my introductory
astronomy classes
is to begin the class with the
Astronomy Picture of the Day.
From the NASA website that
is APOD.NASA.GOV/APOD.
And today's picture for
June the 30th of 2020.
Well, it is titled Bright
Planetary Nebula NGC
7027 from Hubble.
So what do we see here?
Well, this is an example of
a planetary nebula, which
is something that happens at the
end of the life of a star much
like our own sun.
And what happens is
the star builds up
a core of heavier elements
starting with helium hydrogen
fuses into helium then
helium into carbon and oxygen
and neon.
And as that process
continues the core
will collapse down and
crush - crush itself
under its own weight
until it is compacted
to about the size of
the earth forming what
we call a white dwarf star.
Now this is a - And
then at that time.
Now, the outer layers will
be expelled out into space.
Now, what we're seeing here is
one of the very early stages
of a planetary nebula.
This is only based
on measurements
about 600 years old.
So the planetary
nebula phases are
relatively short lived
one lasting maybe
thousands of years anyway.
But this is a very
early stage of one.
So we can see the outer
layers the bluer areas
where we see a material that
has been pushed off from a star.
And we can see inner layers
where more things are still
going on gas and dust are still
being ejected from the star.
Now the process for
a planetary nebula
is still something that is
not completely understood
as to how this works.
When we look at the
planetary nebulae that exist.
We see a wide variety
of different types
and it may depend on
the exact structures.
So one of the thoughts
here is that maybe models
show that this could be
caused by a binary system
at the center.
So perhaps there are two
stars there, one of which
is beginning the
planetary nebula phase.
And then the interaction
of that with the other star
is then causing the
patterns that we see here.
Often we might think that
if it was just one star
it would just push
out material and would
look relatively symmetrical.
We do see some planetary nebulae
like that such as the Ring
Nebula.
So what we also
see more that are
quite complex like this one.
So it may have to do with the
actual workings of the star
or stars that are down
deep within this nebula.
And over time,
this will continue
to expand the outer
layers will continue
to expand outward into
space eventually becoming
seed material for new stars
and could we come back
in tens of thousands of years,
we would see the white dwarf
star left at the center.
And maybe that will
give us a better idea
of what actually
happened here as we begin
to continue to see
we continue to study
how the planetarium
carry nebulae work.
And again, most things
in astronomy one
of the difficulties is that we
can't sit there and watch one.
This has been a 600 year
process since it started
and it is thousands
of years to go.
So it is not something that one
individual astronomer or groups
of astronomers can study.
This has been going
on for centuries
and will continue for a
long time into the future.
So we have to require making
models and trying to understand
what could explain this.
But in terms of
timing, it just takes
too long for many
astronomical events
to be able to be observed
in a human lifetime.
So that was our picture of the
day for June the 30th of 2020.
It was titled Bright Planetary
Nebula NGC 7027 from Hubble.
We'll be back again tomorrow
for the next picture.
So until then, have a
great day, everyone,
and I will see you in class.
