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
March the 2nd of 2020.
Well, it is titled Sharpless
308: The Dolphin Nebula.
So what do we see here?
Well, this is a cloud of
gas known as the Dolphin
Nebula for its distinct
shape and maybe the bulge out
to the upper left.
That may give the appearance
of a Dolphin's snout
and it is an example
of a nebula around
what is called a
Wolf-Rayet star.
Now the star here is actually
visible at the center.
The bright star at the center
is what is causing all of this.
And it is a very massive star.
Many more many times
the size of our own sun.
And is the type of
star that we expect
would eventually go
supernova and explode.
And this is thought to be
one of those earlier stages
where material that
has been pushed off
in earlier phases
of its evolution
is now being illuminated.
So the shock waves from the star
itself before long before it
explodes but of material
being expelled out then
will hit other material
in the interstellar medium
and will become excited
and caused to glow.
And you can see a number
of these shockwaves
especially up towards the upper
right as material condenses
together.
Now, what will happen
to this eventually
is that the star
will finally explode
and that star will
become a supernova.
This occurs when it builds
up an unstable core of iron.
iron is the most
tightly bound element
and could not be fused
into anything else.
So stars no longer
have an energy source.
Once they build
up a core of iron
and eventually the
pressures and temperatures
will get so much that the
entire core will disintegrate
and the whole star will
collapse down and then
rebound out in a massive
supernova explosion.
So something we
have to look forward
to over the next
million years or so.
But here we're looking
at an early stage.
And the blue coloring
is a false color
made from the emission
of oxygen atoms
when oxygen atoms are
excited or any atom.
They give off very
specific colors.
And here we're
looking at those that
have been given this
blue coloration for us
to be able to see
that kind of a glow.
So we see that oxygen
glow in the nebula
surrounding the Wolf-Rayet
star, which again, will likely
explode in a supernova with
the in a million years or so.
And that will then
again, completely
change the landscape of
what is going on here as it
tears itself apart.
So that was our picture of the
day for March the 2nd of 2020.
It was titled Sharpless
308: The Dolphin Nebula.
We'll be back again tomorrow
for the next picture previewed
to be Around the Moon.
So we'll see what that
is about tomorrow.
And until then have a
great day, everyone.
And I will see you in class.
