TJO News
The Theodor Jacobsen Observatory Newsletter
A Quarterly Newsletter
Autumn/Winter 2006
What’s a Sunspot?
What did Charles See?
By:
Rachel MacDonald
Page 1
By:
Joe Huehnerhoff
Page 2
What’s a
Sunspot?
By:
Rachel MacDonald
A sunspot is a place on the
surface of the Sun that has a
cool temperature temperature and an intense magnetic
field. People have been interested in sunspots for
hundreds of years—Galileo
made drawings of sunspots
in 1612.
How cool is a sunspot? The
average temperature of the
surface of the Sun is about
10,000°F, and the average
temperature in the center of
a sunspot is 6400°F. Quite a
difference! This is why the
sunspots appear black to
us—have you ever seen
metal heated up, in person
or on TV? It gets hot
enough to burn you while it's
still black, so we think of it as being quite hot. But if
you keep heating it, it turns red, then orange, and
then almost white. This is what's going on with the
Stars: from Conception
to Birth.
By:
Brian Oldfield
Page 3
Efforts of a UW Undergrad: Uncovering the
mystery of a peculiar
‘winking’ star.
By:
Devin Silva
Page 4
sunspot and the rest of the Sun's surface. The normal surface is heated to the orange-white stage, but
the sunspot is so much cooler that it looks dark.
How intense is the magnetic field? On the surface
of the Sun the magnetic field is typically about twice
as strong as it is on the surface of the Earth. In the
middle of a sunspot, the magnetic field can be anywhere from 2000 to 4000 times as strong as the magnetic field on the surface of the Earth. This is something like the difference between the little magnets
you use to keep notes
on the refrigerator, and
the huge magnets on
cranes used by junkyards to pick up entire
cars.
Astronomy’s Impact on
Physics
By:
Lukas Svec
Page 5
the magnetic north pole of the planet. Unlike Earth's
field, the Sun's magnetic field routinely switches
polarity--what was the magnetic north pole becomes the magnetic south pole, and vice versa.
(Earth's magnetic field does switch, but not regularly, and only every few hundred thousand years,
so it's not the same kind of event.) The Sun's switching happens approximately every 11 years. What
does this have to do with sunspots? The sunspot
cycle is also approximately 11 years long.
At the beginning of their 11 year cycle, sunspots
form far from the Sun's equator (about halfway
between the pole and the equator). Throughout the
cycle, each new spot or group of spots forms a little
closer to the equator, until at the end of the 11 years
they are forming very near the equator. Then the
Sunspots are related to
the magnetic field of
the
Sun.
Magnetic
fields inside planets
and stars can be pictured as if they were
bar magnets that you
can buy at the hardware store. There is a
north magnetic pole
and a south magnetic
pole, and the field
stretches between them.
The Earth's magnetic field is what allows compasses
to work-–the needle of a compass is a magnet and
automatically aligns itself so that it points toward
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next cycle starts, and they
begin forming far from the
equator again. If you plot
this over a large number
of years, you get a diagram that looks like
someone laid pairs of
butterfly wings on either
side of the equator, one
pair after the next—this
appearance has earned
them the name "butterfly
diagrams" (see Figure 3 for
an example). Plotting them this way allows astronomers to easily see trends in both location and
size of the sunspots.
Sunspots always form in pairs--one in the northern
hemisphere and one in the southern hemisphere.
These pairs of sunspots are of different magnetic
polarity--if the one in the northern hemisphere is a
magnetic south, then the one in the southern hemisphere is a magnetic north. This polarity stays the
What Did
Charles See?
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• Long term trends in
sunspot activity could
affect climate here on
Earth (read about the
Maunder Minimum to
find out more).
same during one 11 year cycle. At the end of that 11
years, the magnetic field reverses (north becomes
south and vice versa), and the sunspots also reverse
polarity.
Why should we care about sunspots?
• Sunspots are related to
solar flares and other solar
activity that can impact
our satellite communications and other electronics.
• They're fascinating all by themselves! Why
should some places on the Sun be cooler than others? Why does the magnetic field change so often
and so regularly? These are all areas of current
research among astronomers.
• The more we learn about the Sun the more we can
learn about the Earth's formation, history, and future.
From that time on, Charles committed his life to
searching for comets. This led to the discovery of
several comets as well as other objects including
stars, nebulae, and even galaxies. Two objects he
discovered were comet 1763 Messier and comet 1764
Messier. The comets were named after the type of
object (comet), the year discovered, and the discoverer (Messier).
By:
Joe Huehnerhoff In 1769 Charles published the first edition of the
Charles Messier, that is.
But why should anyone
care about an old, longdead astronomer? The
answer is simply that out
of bewilderment and
passion for the sky Messier created one of the
most prominent astronomical
indices,
the
Messier Catalog.
aptly titled Messier Catalog.
This catalog was of stationary bright sky objects,
meaning it did not include
the comets he had discovered earlier. At the time of
publication the catalog
only had 41 objects. These
objects were referred to
with an M followed by the
object number, the first
object being M1. In the
following years he added
more and more objects,
finishing with 110. In 1774,
Charles started collaborating with Pierre MÈchain.
With the help of MÈchain
several more objects were
discovered adding to the
He was born on June 26,
1730, in the small town of
Badonviller. Young Charles saw wonderment in
the sky growing up in the
Photo credit: NASA and European Space Agency
Lorraine region of France.
(ESA)
When a great 6-tailed
comet
appeared
Messier Catalog.
(seds.org), he became even more captivated by the
heavens. At the age of 21 Charles took a mentorship Although people may not know where Charles
with astronomer Joseph Delisle. Delisle taught Messier was born, why he liked astronomy, or what
Messier the basics of astronomy including how to his first name was many people do recognize his
record the coordinates of the objects he observed cataloged items, such as M31 or M1. If you don't
(seds.org).
recognize the catalog number then the names may
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Photo credit: NASA and European Space Agency (ESA)
help. M31 is also known as the Andromeda Galaxy,
one of the most well known galaxies outside of our
own Milky Way. The Andromeda Galaxy is an
amazingly large (Sb type) spiral galaxy. It is the
largest galaxy of the family (or cluster) of galaxies to
which the Milky Way belongs. Andromeda is
250,000 light years in diameter and nearly 2.9 million light years away from our galaxy.
M1 on the other hand is a spectacular supernova
remnant now called the Crab Nebula. The original
supernova explosion was first spotted by Chinese
astronomers in 1054 A.D., but the remnant nebula
was discovered independently by Messier and John
Bevis. This viciously beautiful aftermath of an explosion can be found in the Taurus constellation. At
the center is a pulsating neutron star. The pulsar
rotates at a stunning 30 times per second. Emitting
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enormous amounts of x-rays, this pulsar has been
an excellent calibration source for x-ray astronomy.
When you are outside observing the sky on our
chilled Seattle nights and turning your telescope
heavenward be thankful to Charles Messier you
only need to look in a book to find some of the most
spectacular sights the nighttime has to offer.
Stars: From
Conception
to Birth.
By:
Brian Oldfield
Have you ever found yourself standing underneath
a starry night sky on a warm summer evening,
wondering where all those tiny points of light come
from? If you are far enough away from urban areasanywhere east of the Columbia river on I-90 and
west of Spokane- you can see the answer. The
bright band you see running across the sky from
horizon to horizon is part of the Milky Way, our
galaxy. If you look closely you will notice dark
patches within this band where
there appear to be no stars.
These patches are the result of
gas and dust which permeate
our galaxy, known as the interstellar medium. It is from this
collection of Hydrogen, Helium, and other molecules that
the stars which populate the
night sky are formed. But how
does this diffuse gas and dust
change from a dark patch in the
night sky into a bright star?
The interstellar medium is buffeted by strong forces such as
pressure and gravity. Much of
the time, the interstellar medium
is in a state where all the different pressures exerted on it balance each other - a state which is
known as hydrostatic equilibrium. An easy way to picture
this is blowing a soap bubble.
After you blow the bubble, and
while you're watching it float
away, the bubble is in hydro-
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For more information consider the following links:
www.seds.org - contains the Messier Catalog and
more information regarding Charles Messier
www.ipac.caltech.edu/2mass/gallery/messiercat.ht
ml - this is a 2MASS survey of the Messier objects.
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http://chandra.harvard.edu/photo/2002/0052/mo
vies.html - This site contains stunning movies of the
Crab Nebula taken by the Chandra X-Ray Observatory.
Images by: National Optical Astronomy Observatory/
Association of Universities for Research in Astronomy/
National Science Foundation
static equilibrium; the
pressure of the air you
blew into it (in order to
make it) is equal to the
pressure of the air surrounding it. Eventually
the hydrostatic equilibrium of the bubble will
be disrupted, for example, by a gust of wind.
As the wind presses
against one side of the
bubble the pressure
there increases and
leads to an imbalance
of pressure over the
rest of the surface of
the bubble, causing it
to pop.
variety of sources, such
as the collision of two
separate collections of
gas and dust or, perhaps
most
poetically,
the
death of a nearby star - a
supernova.
However,
unlike the soap bubble,
the cloud of gas and dust
doesn't pop. Because of
its huge size, the gravitational attraction each
dust molecule has for
each of the other moleThe Orion Nebula as seen by the Hubbell Space
cules causes it to instead
Telescope. Photo credit: NASA and European Space
collapse in onto itself.
Agency (ESA)
As the cloud begins to
collapse it may break up
into smaller clouds, each with the potential to form
a new star.
In a fashion similar to the soap bubble, the hydrostatic equilibrium of the interstellar medium can be So how does a giant collection of gas and dust
disrupted. The forces responsible for this can have a change from being cool to having temperatures far
greater than any we may see on
earth? To understand this we
must understand energy. Picture yourself standing on top of
a tall bulkhead at the beach.
What happens when you step
off of it? Yes, this is an easy
question, you fall down to the
sand below. As you stand at the
top of the bulkhead you experience a certain degree of attraction to the earth, and depending
on just how tall the bulkhead is,
this attraction gives you a certain amount of potential energy-- or energy that will lead to
motion given the proper conditions, such as stepping off the
bulkhead. The amount of potential energy you have while
standing on the bulkhead is the
amount of energy you would
have to expend to jump from the
sand below up to where you are
at the top. As you step off the
top of the bulkhead your potenThe Summer Milky Way. Photo credit: Wei-Hao Wang
tial energy changes into the
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energy of motion (called kinetic energy). When you
strike the ground the kinetic energy you've gained is
converted yet again, this time into energy in the
form of heat and sound, with most being absorbed
by motion of your arms and legs.
Going back to stars, before the clouds begin to collapse they have a certain amount of potential energy
that is converted into kinetic energy (motion) as the
particles come together. But unlike when you
jumped from the bulkhead, the cloud has no legs or
arms to absorb the energy within it. Instead, this
energy goes into heat which, when the cloud has
Efforts of a UW
Undergrad:
Uncovering the mystery of a
peculiar 'winking' star.
By:
Devin Silva
The last time you saw a truly impressive disappearing act was probably at a run of the mill magic
show, which left you wondering how on Earth the
magician pulled it off. Ultimately, you know it was
all just clever tricks with smoke and mirrors, but
what happens when an entire star decides to put on
a little disappearing act of its own? Since the summer of 2005, I have been trying to find an answer to
that question. My target: KH 15D.
And yes, to answer your first question, KH 15D is
the name of a star. Its name is nothing nearly as
exciting as Betelgeuse, Sirius, or Polaris, but KH 15D
makes up for its lackluster name with some rather
quirky behavior. Nestled snuggly in a young cluster
of stars, KH 15D appears to be engaged in an interstellar game of peek-a-boo, hiding itself from view
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collapsed as much as it can, will cause it to burn.
This burning is not that which you and I are familiar
with, but rather a form of nuclear fusion - the combining of two atomic nuclei - that only occurs at the
extremely high temperatures and pressures like
those found in stars. From the time this whole
process begins to occur to the point where a new
star begins to shine depends on the size of the star
which is forming. For the most massive stars called O-type stars - collapse occurs over hundreds
of thousands of years, whereas for smaller, less massive stars like our sun - a G-type star - the time is
closer to tens of millions of years!
If you are curious what newly formed stars look
like, find a telescope and look towards Orion. If you
look just below his belt, to the bright point in the
middle of his sword, you can see a recent area of
star formation called the Orion Nebula. Within the
Orion Nebula you can find young stars as well as
areas of current star formation. So remember, the
next time you find yourself standing underneath a
bright starry night sky, those dark patches you see
above you are not as boring as they might appear,
because someday they may just harbor a new generation of stars to adorn the night skies.
every 48 days. As a result, I have been spending the
last ten months trying to find a way to explain the
smoke and mirrors behind KH 15D's magical act.
causing extensive confusion. His willingness to
devote his time to help me through my project was a
major component to my success.
The first step towards achieving my goal was to At this point, ten months from the time I started the
review the work that had already been done by project, I have successfully developed a model for
previous astronomy
researchers.
After
thumbing
through
various journal papers about KH 15D, I
gained a basic understanding of what
professionals in the
field of astronomy
thought was going
on with the peculiar
star.
The overwhelming theory is
that KH 15D is actuNow you see it... Now you don't!
ally part of a binary
star system, meaning
it is locked in orbit
with a stellar companion. In addition, the two stars KH 15D that describes not only the motion of the
are most likely surrounded by a ring of dust and binary star system, but also the effects that the ring
gas. At this point in my research, I began to get a of dust and gas have on the light we receive from
the star. My model, though not entirely complete at
glimpse at the astronomical magician's big secret.
this time, sheds some light on the mystery behind
The reason that KH 15D periodically fades from our KH 15D and eventually should be able to explain
view is due to the fact that its orbit brings it behind the system completely. In the end, KH 15D's astrothe ring of dust, blocking the light from the star, and nomical smoke and mirrors are no match for pure
effectively making it disappear. Now that I knew science.
all of the tricks that KH 15D had up its sleeve, it
was time to try to come up with an accurate model For more information on undergraduate astronomy
to explain the system in detail and determine if my research opportunities available at the University of
Washington visit:
predictions were correct.
To get started on my model, I needed to expand
my knowledge of binary star systems. This is
where my faculty mentor, Eric Agol, came to my
rescue. At the start of my research project, my
exposure to astronomy was somewhat limited so
Professor Agol provided me with various resources
to expand my understanding of the topics I needed
to create my model. In addition, he took the time
to meet with me and discuss any areas that were
An artist's renditin of what the KH 15D system might look
like. courtesy of: www.astro.wesleyan.edu/bill/research/
kh15d/index.html
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http://www.astro.washington.edu/undergrad/proj
ects.html
For more information on KH 15D visit:
http://www.grammai.org/jhoffman/kh15d/
http://www.astro.wesleyan.edu/~bill/research/kh
15d/
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Astronomy’s
Impact on
Physics
By:
Lukas Svec
Astronomy typifies the ideals of scientific endeavor.
It is the pursuit of knowledge without immediate
concern for practical application. Even so, the
knowledge of the space we inhabit has provided us
with some important applications- particularly to
physics, the closest subject to astronomy.
To a large degree, astronomy is the observation of
light that travels to the earth. From this, we can
learn a great many general things about the particular solar body we are observing. We can learn the
type of object the light comes from, its size, its position, its path and speed, and in most cases the elements that make it up. Finding all this information
is hard in it of itself. It takes time, scientific instruments, and precision. The challenge is further magnified by the shear amount of solar bodies we can
observe. Even to the naked eye there are more stars
in the sky than can be counted in a single night.
Photo credit: NASA and European Space Agency (ESA)
Before the 1600’s, the main motivation for getting
into astronomy was to find patterns in the motion of
the heavenly bodies. There were clear patterns that
people found, but none of those patterns corresponded to the motions of objects on Earth. There
was a divide between the laws of space and laws on
Earth. Up until that time, the most advanced laws
up were discovered by Kepler in 1604. Using empirical data on the positions of the planets in our
solar system, he identified three laws that accurately
predicted their path and speed. More specifically, he
showed that the planets in our solar system traveled
along an elliptical path. Even though these laws
were accurate, they were self contained- they didn’t
tell us more than where a planet would be on a
given night- because it didn’t explain why they
moved the way they did.
About half a century after Kepler’s discovery, Newton came up with his own three laws that described
the motion of objects on Earth. One of the biggest
validations of his theory came from its agreement
with Kepler’s three laws. Furthermore, Newton’s
discovery provided an answer to why planets traveled in elliptical paths: a force, which they called
gravity, pulls objects toward each other. By using
astronomical data, Newton was able to show that
the laws governing motion on the surface of the
Earth are the same as those governing motion everywhere in the universe. Newton’s discovery was a
huge leap. It changed the way people perceived the
universe by allowing people to see space as a large
laboratory in which physics experiments could be
ran by observing the correct conditions.
One of the first and most famous applicable uses of
astronomy was in the verification of Einstein’s theory of general relativity in 1919. In 1915, Einstein
theorized that light doesn’t exactly travel in a
straight line. It bends due to gravity (toward heavy
objects) in the same way as a ball bends toward
heavy objects (like the Earth), except at a much
smaller amount. Such a small amount, in fact, that it
was not possible to notice this in an experiment set
up in a normal laboratory. The most convincing
experiment would have to be tested in space. Under the direction of Arthur Eddington, the leading
British astrophysicist of the time, astronomers
searched the skies for the right conditions. It took
four years for an opportunity presented itself in the
form of an eclipse.
allowed for stars to be seen, which acted as light
sources. When the sun moved closer to the stars, the
stars appeared to move away, which indicated that
light did indeed bend around massive objects- proving Einstein’s general theory of relativity.
It took three centuries for the knowledge
astronomy has gathered to find an important application to physics. It has almost been another century
after the verification of Einstein’s theory of relativity
and astronomy has become more and more applicable. The largest applications are yet to come when
we will no longer be limited to observing light from
afar, but when we find ways to retrieve samples of
the heavenly bodies efficiently and in quantities.
References:
Küpper, Hans-Josef. “Short life history: Johannes
Kepler,” 2000, einstein-website, 9 May. 2006
http://www.einstein-website.de/biographies/kepl
er_content.html
“People in the History of Astronomy,” 1997, 9 May.
2006
http://www.geocities.com/CapeCanaveral/Launc
hpad/4515/HISTORY.html#Einstein
Coles, Peter. “Eclipse that Changed the Universe,”
2005, firstscience.com, 9 May. 2006
http://www.firstscience.com/site/articles/coles.as
p
Since Einstein theorized that light bends when it
travels around heavy objects, an effect should be
noticeable by using sun, which is extremely massive. This would mean the experiment would have
to be run during the day. So in order to see light
bent around the sun, an eclipse had to occur. This
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