Transcript Day 2 - IISME Community Site

DAY 1
Focus: Brown Dwarfs
Essential Questions:
What are brown dwarfs?
What can you learn from recognizable patterns in data?
Agenda:
• Warm up: Jigsaw Exercise (.ppt) (Part1)
• Write down what comes to your mind when you look at the poster and why. Do this within your
group be able to explain why.
• Students will join with three other group that has a different poster and piece all the clues
together and make a collective poster about ‘What is a Brown Dwarf’
• Collective poster should address –
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What is a Brown Dwarf?
What is its temperature?
Is Brown Dwarf same size as a planet and star?
If not then how is the brown dwarf different?
What objects in the universe are called cool? Is this a relative term? (some prior knowledge may be
needed)
What ‘missing links’ is the Missing Link poster talking about?
Each collaborative group presents their poster (Part 2)
Students will write in their notebooks /ejournal what they learned about Brown Dwarfs
Introduce my work at ucsd ‘Cool Star Lab’ (.ppt) (Part 3)
No astronomical objects between the large planets and low mass stars
First discovered in 1995
Is brown dwarf really a star?
Day 1 – Part 1
*
* Review the poster given to your table group and write down all that
comes to your mind and why as a group.(next slide has the four
posters)
* Get together with three other group who should have a different
poster than yours and add to your understanding of brown dwarfs.
* End product – group poster that addresses the following
1.
2.
3.
4.
5.
6.
What is a Brown Dwarf?
What is its temperature?
Is Brown Dwarf same size as a planet and star?
If not then how is the brown dwarf different?
What objects in the universe are called cool? Is this a relative
term? (some prior knowledge may be needed)
What ‘missing links’ is the Missing Link poster talking about?
* Present the poster to others in the group
Astro.washington.edu
DAY 1 – Part 1(Posters for the Jigsaw)
Bbogs.discovermagazine.com
en.wikipedia.org
eso.org
Day 1 – Part 3
Invisible Stars – Hidden World of Brown Dwarfs
Artist rendering of WISE 1828+2650 (a brown dwarf).
Credit: NASA/JPL-Caltech
Day 1 – Part 3
* Who? Dr. Burgasser
* What? Spectra
http://www.ipac.caltech.edu/outreach/Edu/Spectra/
spec.html
* How? Study BD in Infra Red spectrum
* Why?
* Link between planets and cool stars
* Clues to formation of planets
*
*The flux is the thing
* The message in starlight is entirely encoded within the
measured flux
* Flux = Energy received /m2 / sec
* Spectrum = flux variation with wavelength
* Star composition (what stars are made of)
* Star types (classification scheme)
* Star temperatures (stellar thermometer)
* Star rotation motion (Doppler effect)
* Star distances (standard candles)
* Magnetic fields, mass loss, …….
*
The Stars - as physical objects
* Observations
* Stars emit energy into space
* We know this because we can “see” them and light is a form of EM
radiation, and EM waves carry energy
We also know that some stars are brighter
than others – this relates to measured flux
The greater the flux, the brighter the star appears to us
Question:
Are brightness differences due to variations in stellar
luminosity or distance (or both) ?
* Stellar spectra
* Stars radiate most of their
Sun-like stars
EM radiation at UV, Visual
and IR wavelengths
* They also show distinctive
Absorption
lines
absorption lines due to
specific atoms (hydrogen,
helium,…) and in some cases
molecules in their outer,
cooler layers – an atomic
“thumbprint”
* Absorption lines can be used
to study stellar composition,
surface temperature …
Spectral classification scheme
Credit – Dr. Burgasser, UCSD cool star lab
Credit – Dr. Burgasser, UCSD cool star lab
Credit – Dr. Burgasser, UCSD cool star lab
Not Enough Brown
Dwarfs to account
for all dark
matter!
Credit – Dr. Burgasser, UCSD cool star lab
Credit – Dr. Burgasser, UCSD cool star lab
End Day 1 – Part 3
Day 2
Focus: Classification and Pattern Recognition
Essential Questions:
What is the basis of any classification?
How do you investigate patterns in a given data sample?
What can you learn from recognizable patterns in data?
Agenda:
• Warm up: As a table group come up with one way to group/classify
students in this classroom. Need to write down reason for this
grouping (Part 1)
• Each table shares out their reason for classifying students
• Students get a set of spectra and they have to come up with a way
to bin them into groups and make preliminary inferences based on
the grouping.(Part 2)
• Students check with other groups and share the total number of
groups and the basis for the classification
• Students come up with why the spectra are similar for some and
different from others. Questions they would like to explore.
• Students will also use opacity cards to match with the spectra of
brown dwarf to determine what molecules may be present in brown
dwarfs.
Day 2 – Part 1 (example of how to group objects if students need it)
Example – How to classify/group a given set of objects (in this case buttons)
Day 2 Part 2 -
*Students get a stack of spectra cards (10 – 12/group)
* Students need to classify the spectra and complete the flow chart.
(this is an exploratory/discovery activity so no instruction should be
given to student about how to classify). If students insist on need
help ask how would they classify the spectra just by looking at them.
* (for teacher) The quick and simple way to group spectra is to hold up
one spectra to the light and put another over it to see how well the
two match and classify accordingly. If it matches same class if not
then another class. You look for similar pattern in the spectra. I have
attached a slide to explain what is in the spectra card
* Check with other groups how many groups they have and the basis
for the grouping. They will combine their grouping to come up with a
classification for the whole class (see notes)
* Students also share what questions they would like to explore about
brown dwarfs and spectra
* Students will use opacity cards to figure out what atoms/molecules
may be present in the spectra – (how to details in another slide)
Day 2 Part 2 Spectra Cards
1
* About the spectra cards
* fλ = normalized flux for the object
* Flux is the energy received per unit area per
second, fλ is the energy received per unit
area per second per wavelength
* Wavelength is measured in micron same as
micrometer(µm).
* 1 µm = 10-6 m
2
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Overlap one spectrum on another and
look for an approximate match in the
pattern..
* There are 80 individual spectra in the file
teacher should print and cut it up and divide
into stacks of 10 or 12 to be given to group
of students
* Students will classify spectra by holding two
spectra at a time to the light to check for
match.
* Will end up with three distinct class of
spectra.
* Students will complete flowchart provided
and compare results with other groups in
class
Day 2 Part 2 Opacity Card
* About the opacity cards
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Spectrum Card
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Take the spectrum card and overlap with opacity
card look for matching dips. You are not looking for
an exact match. In the case above two dips match
and gives us clue that water molecule is present in
this brown dwarf spectrum. .
Each student group will be given a set of 6 opacity cards
σ = opacity
Opacity is the removal of energy from a beam of photons
as it passes through matter.
We can also define opacity as the amount of light that is
able to get through when passing through an atmosphere
of a given molecule.
High opacity less light makes it through meaning more light
is absorbed by the molecules present in the brown dwarf.
Low opacity means more light makes it through
Wavelength is measured in micron same as
micrometer(µm).
1 µm = 10-6 m
There are six opacity cards for different molecules. Print
and cut it up into individual spectra.
Student will match them to their spectra to figure out
which molecules have a strong presence in each class of
brown dwarf.
Best is to hold the opacity card over a spectrum card and
look for matches. This is not an exact match best to check
if parts of the two spectrum have the same absorption
(dips) at the same wavelength.
In the spectrum card on the right a little before 1.5 µm and
2.0 µm the absorption feature matches with the
absorption at same wavelengths in the water molecule
opacity card above it.
Day 2 Part 2 -
*For teacher:
* End of spectra classification will result in three distinct
set of
spectra.
* Matching with the opacity cards will determine what molecules are
present in the atmosphere of the different classes of brown dwarfs.
*For Students:
* Regroup students and let them record in their journals …
* How many different groups of brown dwarfs did they have?
* What was the basis for the grouping?
* How did they identify molecules present in the brown dwarf atmosphere?
(should describe comparison of spectra of brown dwarf with known molecule
spectra /opacity cards.
* Discuss how they can quantify relative presence of a given molecule between
different classes of brown dwarfs ( if most of the absorption lines in the
molecule matched the brown dwarf or only some of the absorption lines in
the molecule card matches the brown dwarf spectra card
Day 3 -
*Outside class research/physical notebook/ ejournal
on Edmodo (maybe done as an in class research)
* Use info from the previous class to add to the understanding
of Brown Dwarf and answer the following questions -
1.
2.
3.
4.
5.
6.
How many classes of brown dwarf are known?
What is the range of temperatures for Brown Dwarf?
Why was it difficult for brown dwarfs to be discovered?
What are the brown dwarfs a link to?
What current technology is used to study brown dwarfs?
What are brown dwarfs - stars/planets/something else?
Explain
* (students will be provided a basic web link list for research
on and Edmodo site, word document
(SummativeAssessmentResearchInstruction)of web link is
included in attachment)
Day 4
Focus: Decipher brown dwarf spectra
Essential Questions:
* What information can you get from the brown dwarf spectra?
* What is the relationship between spectra and composition of the
brown dwarf atmosphere?
Agenda:
* Warm up:
Compare the spectra of the given star and planet to that of the
brown dwarf and predict the composition of the planet’s atmosphere.
* Students work collaboratively to understand the questions they
researched.
* Students work on their presentation
* Presentation group has to be a two student group at minimum and 5
student group at a maximum
* Presentation can be in the format of a poster, song, jeopardy or any
other approved format of your choice.
* It should address all parts of the rubric
*
Day 5
Focus: Showcase understanding of Brown Dwarf
Essential Questions:
* What clues would tell you that a given spectra is a brown dwarf?
* What clues in a spectra will tell you that it does not belong to a
brown dwarf?
Agenda:
Warm up –
Be ready to present your work on brown dwarf.
* Students will make a group/individual presentation about
brown dwarfs to the class.
* Take questions from peers and teacher.
* Class thanks each group post presentation and question
answer session
* Students share what they did well and where they feel they
need to improve