Open Clusters
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Transcript Open Clusters
Quic kTime™ a nd a
TIFF (Un co mp res sed ) d ec ompre sso r
ar e n eed ed to see thi s p ictu re.
Open Clusters
Allan Harrell
Edgar Toledo
Tenaya Pusley
Carmen De Martis
What is a star?
A giant ball of gas
Hydrogen
Emits light
Different colors and
sizes
How do stars form?
Form from clouds of
dust and molecular
hydrogen
Gravity collapse
Why doesn’t a star continue
collapsing?
Hydrostatic
Equilibrium
Gravity pushes in….
Pressure pushes
out…
Create an
equilibrium
What are open clusters?
Young stars
Same chemical
composition
Same Age
Distance
Bound by gravity
Form in spiral and
irregular galaxies
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About Main Sequence Stars
Stars spend most of their life in the main sequence,
about 90%
Our sun is 5 billion years into its main sequence
The larger the star, the less time it will spend on the
main sequence
Main sequence stars maintain brightness and energy
through fusion
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Fusion is important!!
1. Fusion
creates energy
2. Energy
raises temperature
3. Temperature
4. Faster
makes atoms move faster
moving atoms increase pressure
5. Pressure
fights against gravity
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http://www.star.ucl.ac.uk/groups/hotstar/images/life_cycle.jpg
“What happens in a high
mass star?”
-
Shorter lifetimes
-
Consumes fuel faster
Fuses more elements.
- Fusion of iron consumes energy
instead of giving off energy.
-
Fuel fusion
http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap21/FG21_05.jpg
“Supernova explosion”
http://imgsrc.hubblesite.org/hu/db/2004/29/videos/d/stills/3/image.jpg
“What happens after death”
It either becomes a:
Black hole
or a
Neutron star.
http://dante.physics.montana.edu/ns_interior.jpg
“Black Hole”
http://www.wvp-consulting.com/astronomy/images/blackhole.jpg
Observations:
Used
the Lick Nickel 40
inch telescope
Observed remotely with
the help of Elinor Gates
Took images of 4 open
clusters
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http://www.ucolick.org/graphics/nickel_lg.jpg
CCDs:
Basic tools of
astronomical imaging
Grids of light buckets
Colorblind
3 different filters allow us
to see color (red, green,
and blue)
Same as the digital
cameras that you may
own
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T IFF (Uncompres sed) decompres sor
are needed to s ee this picture.
Isochrones:
Y=brightness
“Freeze
frame” of a
cluster
Reveals age
of cluster
Made by
computer
X=color and temp.
Which Isochrone Matches the CMD?
A.
B.
This one! Correct! :)
(CMD)
(ISOCHRONE)
How to calculate the distance:
Due to dust
Apparent Mag.
(from CMD)
0.2
(
m-M+5-Ar
)
d=10
Distance
Absolute Mag.
(from isochrone)
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M11
Color Magnitude
Diagram
• y-axis = brightness
• x-axis = color
M11
• Around 2000 parsecs
• Around 6000 light years
• Mostly main sequence
stars
• 200 million years old
•What I found out :
5095 light years from the earth
1.6 billion years old
My Color
Magnitude
Diagram
Open
Cluster
NGC6939
NGC 6819
Apparent Diameter: 5 arc min.
“NGC 6819”
Open star cluster
According to my results:
-It is about 3/4 of the Earth’s lifetime old.
-It is about 7,603 light years away from us.
-Has a metallicity of about 2%---like Sun
“Isochrone”
“CMD”
for NGC 6819
NGC 6791
Observed and
recorded data for
NGC 6791
7.6 billion years old
Looking at
isochrones
4972 parsecs (3.26
light years = 1
parsec)
Isochrones
Puzzles from NGC 6791
It’s really old
Metal rich
NGC 6705
NGC 6791
NGC 6819
Sun
NGC 6939
We would like to thank:
CFAO
Laura
Chomiuk
Kathy Cooksey
Daisy Corral
Liz Espinoza
Emily Freeland
Elinor Gate
•John Martin
•Hilary O’Bryan
•Jay Strader
•Gene Switkes
•Vay Hoang