Download Unit 5 - Stars

Learning Goals:
 How do stars differ from moons and planets, and from
one another?
 How does the classification of stars help us understand
how they evolve over their lifetimes?
 What are the different types of stars?
 What happens when different types of stars die?
 Why is it important for us to understand stars?
Bellwork and FYI + questions. = 9 Minutes (2 songs)
 Bellwork and FYI. = 9 Minutes (2 songs)
Classifying Stars
Questions of the day
 What characteristics help us organize stars
into groups?
 Who determined those characteristics and
how?
We are going to start with the
WHO DETERMINED THESE
CHARACTERISTICS?
We are going to learn
about the most
important person in
the field of star
classification.
 Take notes on what
you believe to be
important. I wont tell
you exactly what to
write down. There will
be multiple test
questions about this
person
Classifying the stars has helped in all
studies of the structure of the
universe. No greater problem is
presented to the human mind.
-- Really Smart Scientist
Education/Awards
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graduated from Wellesley College (1884)
became a student of astronomy at Radcliffe College (1894)
received an M.A. from Wellesley College (1907)
received an honorary doctorate from the University of
Delaware (1918)
was the first woman to receive a doctor of astronomy degree
from Groningen University (1921)
was the first woman to receive an honorary doctorate from
Oxford (1925)
received an honorary doctorate from Wellesley College (1925)
received an honorary doctorate from Oglethorpe University
(1935)
received an honorary doctorate from Mount Holyoke College
(1937)
Annie Jump Cannon
(1863-1941)
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born in Dover, Delaware on December 11, 1863
Annie suffered a handicap in her youth and was
very hard of hearing
At Wellesley College she pursued physics &
astronomy
After graduation, she became an expert in the
new field of photography.
Annie loved to travel and in 1892 she traveled
through Europe taking pictures with her new
box camera
 Annie created a booklet of photos and prose from
her trip. It was published and used as a souvenir
for the Chicago World Fair in 1893. It was titled In
the Footsteps of Columbus. While at home Annie
became unhappy with the way her life was
heading and wrote the following in her journal:
 “I am sometimes very dissatisfied with
my life here. I do want to accomplish
something, so badly. There are so many
things that I could do if I only had the
money. And when I think that I might be
teaching and making money, and still all
the time improving myself it makes me
feel unhappy and as if I were not doing all
that I can.”
 After her mother's death in 1894:
 Annie returned to Wellesley as an
assistant in the physics department and
 became a student of astronomy at
Radcliffe.
 took part in the first X-ray experiments
in the country
 began her work at the Harvard College
Observatory.
 Annie observing in 1895 through a 4-inch
reflecting telescope.
This picture was taken during the 1895-1896 academic
year. This is the laboratory of then Wellesley
professor and renowned physicist and astronomer
Sarah Whiting.
 Annie Cannon at
Oxford in 1925. She
was the first woman
to ever receive an
honorary doctorate
from this institution.
It was awarded for
her contributions to
astrophysics.
 In 1896 Annie was hired by
Professor Edward Charles
Pickering, director of the
Harvard College
Observatory, to catalogue
variable stars and classify
the spectra of southern
stars.
Some of the women were referred to as “computers”
because they handled star classification and complex
data reduction. They were paid 50 cents an hour.
Other women who worked there as assistants were
referred to as “recorders” because they recorded the
data..
Stellar classification according
to line patterns began. This
was not easy to do. Annie
excelled because of her
sharp eye and memory. The
following image is one
photographic plate
containing stellar spectra.
For this particular field she
averaged 3 stars a minute.
She ended up categorizing
over 350,000 stars in her
career
Now we are going to figure out
WHAT CHARACTERISTICS HELP
US ORGANIZE STARS?
Classifying Stars
 What properties could we use to classify
stars? Why?
 Temperature
 Color
 Size
 Spectrum
Classification of Stars
-historical
 Originally- # classification… 1= bright,
6=dim
 Remember Hipparchus?
 Then….
Then- spectrum analysis…
strength of Hydrogen,
starts at A,
goes through the alphabet
Classification - current
Use: Spectrum,
Temperature, and Size
*It was easier to just rearrange the
letters than to reclassify
everything…
 Get rid of repeated
properties
 Put in temperature order
 Temperature and Mass
relationship
 Temperature and stellar
life cycle relationship
ABCDEFGHIJKLMNO
AB
FG K M O
Stars are classified by:
Spectral Class (color , temperature, spectral lines)
- O,B,A,F,G,K,M
-O:Blue, B:Blue/white, A:white, F:yellow/white, G:yellow, K:orange, M:red
Temperature (range within class)
-0, 1,2,3,4,5,6,7,8,9
-0=hottest, 9=coolest
Magnitude (brightness and size)
-0, I, II, III, IV, V, VI, VII
-0 –hypergiants, I –supergiants (Ia and Ib), II-bright giants, III
–normal giants, IV- subgiants, V- main sequence (dwarf), VIsubdwarf, VII-white dwarf
What characteristics do these
stars have?
 B8 I – Rigel
 K5III – Aldebaran
 M2I – Betelgeuse
 F5 IV - Procyon
 A1V – Sirius
 G2V- Sun
 O9.5II -- Mintaka
Classifying Stars
 What characteristics help us organize stars
into groups?
 Who determined those characteristics and
how?