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
January the 7th of 2020.
Well, it is titled IC 405:
The Flaming Star Nebula.
So what do we see here?
Well, this is an example, not
just of one kind of nebula
but actually two different types
of nebulae that are shown here.
And it is known as the
Flaming Star Nebula.
Because we have the
bright star there,
which looks a little
bit purple in this image
and I'll talk about
that in a minute.
And it has the great flames.
The great reddish
orange flames around it.
Now the two different nebulae
are formed by this one star.
And the star is
known as AE Aurigae.
And that is the star there
that looks a little bit
purple towards the center.
The purple color is a
mixture of a couple of colors
of light in regular
and true color,
it would actually
look blue and would
be what we call a
reflection nebula
and is a nebula with some
dust that is reflecting
the light from this very
hot star hot stars primarily
emit short wavelength light.
That's where most of
their energy comes out.
And in fact, this
star emits most
of its light in the ultraviolet
portion of the spectrum.
And then that light is then
reflected by these dust grains
and the dust grains are
better at reflecting
shorter wavelengths.
So bluer lights are reflected.
So in the visible,
it would look blue.
Now it looks purple
here because this
is used as an image
that looks at three
different wavelengths of light
and then color codes them.
So the light of the various
different atom different atoms
that we're looking at are color
coded with different colors.
And that gives us the
image that we see here.
So we look at the emission of
things like hydrogen and oxygen
and sulfur.
And then each emission of
those specific elements
is given a specific color to
allow us to see the image.
And in this case, when you
get the purple color, which
is combining a red
and a blue gives us
that reflection nebula.
That's what we have for our
reflection nebula there.
Now most of it looks
very orange color
and a lot of that is
due to hydrogen gas,
hydrogen gas gives
off a red light.
And here color coded
more towards an orange.
And that is what we see here
with the orange color is
hydrogen emission the
ultraviolet radiation
from the star is ionizing
stripping electrons off
of the hydrogen atoms and
then it strips them off
and then it causes them
to - then they recombine.
And when they recombine
they will give off
the distinct red
color of hydrogen,
which happens to be color
coded here in an orange color.
Now, of course, the
color coding can
be done because some of these
would look similar colors
and allows us to distinguish
between the various different
types of elements that we see.
So we can see here.
And again what is called
the Flaming Star Nebula -
a couple different types of
nebulae The emission nebula
and a reflection nebula.
So that was our picture of
the day for January the 7th
of 2020.
It was titled IC 405:
The Flaming Star Nebula.
We'll be back again tomorrow
for the next picture previewed
to be Galaxies in the River.
So we'll see what that
is about tomorrow.
And until then have a
great day, everyone.
And I will see you in class.
