Purpose:
In these exercises, we
made use of a telescope to find and observe a variety of astrophysical objects
in the night sky. First we learned how to set up and focus the telescope, then
how to focus in on a single object in the night sky. We used star charts to
find our targets.
Supplies
Needed:
· A
free app for Android and iPhones like StarChart
· A
telescope (provided by your instructor)
· Paper
for note-taking
· Messier
catalog and star-charts
Introduction:
The invention of the
telescope 400 years ago, and its first use by Galileo Galili to look at the
sky, changed our perceptions of the heavens forever. Since then telescopes have
changed a lot, from the first refractive telescopes using lenses, to reflecting
telescopes using mirrors. The very first reflecting telescope was designed and
built by Isaac Newton. Today, the biggest telescopes are made with mirrors and
segments of mirrors spanning 10 meters in diameter. Within the next two
decades, the next generation of telescopes will come online with primary mirror
diameters stretching 25-40 meters across.
At Baker Observatory we
have eight-inch primary mirror telescopes for you to use, with tracking motors
to maintain the position of stars in the eyepiece. We also have two 16-inch
telescopes and one 14-inch telescope used for research by out faculty.
Procedure:
A. Setting
Up the Telescope
1. Identify
a group of students to work with, so that there are enough telescopes per
student to go around.
· Gates Bartz and Brooke Masterson
2. First
of all, take extreme care in handling this expensive equipment. Give your eyes
time to adapt to the darkness. Use only the red flashlights available at the
observatory to preserve your night vision.
3. In
the lockers your instructor will open for you, select your telescope and the
corresponding tackle box. They will be labeled with the same number, so they
belong together. The telescope is heavy so take care in moving it, it might be
easier if two people carry it together.
4. Select
one of the metal stands outside to work from and carry your telescope to it.
You want one of the stands that is completely flat on the top. Settle your
telescope on the center peg sticking up from the stand. This will keep it in
place.
5. Once
your telescope is settled on the peg, have another member of your group search
through the tackle bow to find three short screws. DO NOT LEAVE YOUR TELESCOPE
UNATTENDED UNTIL IT IS FULLY SECURED TO THE STAND. These three screws are
placed underneath the telescope. They go through the underside of the plate on
the stand, and into the corresponding holes in the underside of the telescope.
You may have to twist the telescope until the holes line up.
6. Next,
search the tackle box for a power chord and plug it into the corresponding
place in the telescope. There should be a power outlet on the telescope stand
for you to plug the other end into. After you have plugged in your telescope,
find the control pad and plug it into its corresponding spot as well. Don’t
forget to turn on your telescope. (The switch might be covered up with some
tape to block off the LED light.)
7. Now
that your telescope is secured and powered up, you can move the center piece
that contains the mirror. Either twist the cap/dial on the side of the
telescope to allow the center piece to swing upward, or use the control pad to
move it upward.
8. There
are two lens caps to remove (one from either end of the telescope). DO NOT LOSE
THESE. In the tackle box, you should find a wide and shallow lens piece that
will screw onto the small end of the telescope. There is also an elbow piece
bent at a right angle that you will attach to the first piece. Finally, you
will choose a lens that ends in an eyepiece to complete your telescope (Your
instructor can tell you which one). All of these pieces have lens caps on both
ends. Remove them before assembling the pieces together, but again DO NOT LOSE
THEM.
9. Now
that your telescope is all put together, point it to a random place in the
night sky. Looking through the eyepiece, you can see if the stars are clear or
fuzzy. If the stars look like “donuts” you may need to focus your telescope.
You can do this by twisting the middle ring around the eyepiece. You can adjust
this until the stars come into focus.
B. Observing
the Night Sky
1. From
the following list of objects (and the messier catalog in your lab packet),
pick one object to observe in your group. It is best to start with a bright
object like the moon or a bright star or planet, and work your way to fainter
and fainter objects as you gain more experience in each lab.
a) Part
of the Milky Way
b) Andromeda
Galaxy
c) Orion
Nebula
d) Jupiter
e) Saturn
f) Mars
g) The
Moon
h) A
double star
i) An
open cluster, including the Pleiades and Beehive Clusters
j) A
globular cluster
k) A
planetary cluster
l) Any
other object approved by the instructor
2. Using
your star finding app or chart, locate your object in the finder-scope (the
little telescope piggy-backing on the main telescope). Center your object in
the crosshairs of your finder-scope. Once the telescope is aligned in the
direction you want it, find your object in the eyepiece of the big telescope.
This is not easy the first time, and takes practice. Use your hands to
carefully nudge the telescope in one of two directions to search the nearby
part of the sky to find your target.
3. Answer
the following questions about:
M40: A
Binary Star
a) Draw
what you see. If the object is bright enough, take a picture with your phone up
against the eyepiece, and include that in your report.
b) Make
notes about distinguishing characteristics and properties of what you are
looking at. For example, if you are looking at a binary star, how far apart do
they appear to be? Can you see if the two stars have different colors?
· The two stars are a short distance apart, and appear to be near to
the same bluish color. However, the lower star in the pair is clearly larger
than the other star.
e) How
bright is your object? What would you estimate the magnification is of your
eyepiece?
· The binary star system is very bright. The magnification of the
eyepiece has to be something around 100 times at least. This binary star system
still appears relatively small, but is entirely invisible to the naked eye. Not
only can we see the star with the telescope, we can actually resolve it into
the two separate stars of this binary system.
f) Can
you see more stars than you can see with your eye? Particularly with the
Milky Way? Why is that?
· Yes. I can see many more stars with the telescope than with the
naked eye. Many that are too faint to be seen with the human eye can be seen only
with the telescope.
g) If
you are looking at a star, a cluster of stars, or a binary star, why can’t we
see the surface of the stars? Hint: calculate the angle a star’s surface has on
the sky, given the typical distance to a star and the typical size of a star in
diameter.
· Because the star is so far away and so small, it is difficult to see
the surface.
h) If
your object is changing in brightness, why is that?
· Ours was not changing a whole lot, but it would be “flickering” in
brightness due to disturbances in the Earth’s atmosphere.
The Orion Nebula: A
Stellar Nebula
a) Draw
what you see. If the object is bright enough, take a picture with your phone up
against the eyepiece, and include that in your report.
· The Orion nebula is one large star surrounded by a cloud of glowing
bluish (because of the light from the star) dust. Near the nebula are another
three smaller stars off in a line to its bottom right.
e) How
bright is your object? What would you estimate the magnification is of your
eyepiece?
· The nebula is very bright. The magnification of the eyepiece has to
be something around 100 times at least, because the nebula is extremely faint
and fuzzy to the naked eye, but clear and bright in the telescope.
f) Can
you see more stars than you can see with your eye? Particularly with the
Milky Way? Why is that?
· Yes. I can see many more stars with the telescope than with the
naked eye. Many that are too faint to be seen with the human eye can be seen
with the telescope.
g) If
you are looking at a star, a cluster of stars, or a binary star, why can’t we
see the surface of the stars? Hint: calculate the angle a star’s surface has on
the sky, given the typical distance to a star and the typical size of a star in
diameter.
· Because the star is so far away and so small, it is difficult to see
the surface.
h) If
your object is changing in brightness, why is that?
· Ours was not changing a whole lot, but it would be “flickering” in
brightness due to disturbances in the Earth’s atmosphere.
4. Once
your instructor gives the okay, take down and put away your telescope.
Conclusion:
During this lab, we once
again set up the telescopes at Baker Observatory. This was easier the second
time. During the time allotted to us, we closely observed the Orion nebula, and
the binary star system M40. One of the biggest problems we faced was finding
objects to observe, as most were below the horizon and out of visibility.
However, as I said, we did manage to observe M40 and the Orion Nebula. Below is
some more information about these two objects, beyond what can be seen with the
telescope alone.
The
Orion Nebula:
I credit all of the
information to NASA. The Orion Nebula is known as M42 and it is only 1,500
light years away. The nebula’s flowing
gas surrounds hot young stars as they are forming in a huge molecular
cloud. It is a great opportunity for
people to see how stars are born because it is the closest area in our galaxy
that is making young stars, and it is a large star-forming region. It’s also great to view because the nebula’s
energetic stars have blown away the dust that would have obscured our
view.
This nebula is located in
the constellation Orion, and (for obvious reasons) often referred to as the
Orion Nebula. A fun fact is that, due to
the closeness of the nebula and absence of dust blocking our view, this nebula
is often visible to the naked eye if the person looking is not in or near a
large city. It was the first object of
its kind to be photographed.
M40:
M40, or Messier 40 was
discovered first by Charles Messier in 1764. He found the binary star while
searching for a nebula in the area reported by Johannes Hevelius. While he
couldn’t find the nebula that was described, he did record the binary star
system. It was then recorded again later in 1863 by August Theodor Winnecke.
Since this time, there has been significant evidence gathered by two different
astronomers, Brian Skiff in 2001 and Richard L. Nugent in 2002, about the M40
star system. Both astronomers found evidence that it is much more likely M40 is
simply an optical double star than a real binary star system. This means that
the two stars are, in reality, very far apart and only look close together from
our perspective here on Earth.
A
real binary star system is when two stars are formed together at the same time
and orbit each other. Their orbit can usually be seen from Earth in where they
either circle each other or transit in front of one another. This is also one
way to measure various characteristics of one star or the other, by measuring
how much the luminosity decreases when one star crosses the other’s path from
our viewpoint. Also, if one star is older (and larger) than the other, the
stars can transfer mass from one to the other if the smaller star’s gravity is
strong enough and the older star is large enough. This can effectively shorten
the life span of the younger star, by increasing its mass and leading to a nova
(or supernova depending on the type of star it is).
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