Open Clusters

Open ClustersOpen Clusters

Allan HarrellAllan HarrellEdgar ToledoEdgar Toledo

Tenaya PusleyTenaya PusleyCarmen De MartisCarmen De Martis

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

What is a star?What is a star? A giant ball of gasA giant ball of gas HydrogenHydrogen Emits lightEmits light Different colors and Different colors and

sizessizes

How do stars form?How do stars form? Form from clouds of Form from clouds of

dust and molecular dust and molecular hydrogenhydrogen

Gravity collapseGravity collapse

Why doesn’t a star continue Why doesn’t a star continue collapsing?collapsing?

Hydrostatic Hydrostatic EquilibriumEquilibrium

Gravity pushes in….Gravity pushes in…. Pressure pushes Pressure pushes

out…out… Create an Create an

equilibriumequilibrium

What are open clusters?What are open clusters? Young starsYoung stars Same chemical Same chemical

compositioncomposition Same AgeSame Age DistanceDistance Bound by gravityBound by gravity Form in spiral and Form in spiral and

irregular galaxiesirregular galaxies

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

About Main Sequence StarsAbout Main Sequence Stars

Stars spend most of their life in the main sequence, about 90%Stars spend most of their life in the main sequence, about 90% Our sun is 5 billion years into its main sequenceOur sun is 5 billion years into its main sequence The larger the star, the less time it will spend on the main sequenceThe larger the star, the less time it will spend on the main sequence Main sequence stars maintain brightness and energy through fusionMain sequence stars maintain brightness and energy through fusion

Fusion is important!!Fusion is important!!

1.1. Fusion creates energyFusion creates energy

2.2. Energy raises temperatureEnergy raises temperature

3.3. Temperature makes atoms move fasterTemperature makes atoms move faster

4.4. Faster moving atoms increase pressureFaster moving atoms increase pressure

5.5. Pressure fights against gravityPressure fights against gravity

http://www.star.ucl.ac.uk/groups/hotstar/images/life_cycle.jpg

““What happens in a high What happens in a high mass star?”mass star?”

- Shorter lifetimesShorter lifetimes- Consumes fuel fasterConsumes fuel faster- Fuses more elements.Fuses more elements.- Fusion of iron consumes energy Fusion of iron consumes energy

instead of giving off energy.instead of giving off energy.

Fuel fusionFuel fusion

http://physics.uoregon.edu/~jimbrau/BrauImNew/Chap21/FG21_05.jpg

““Supernova explosion”Supernova explosion”

http://imgsrc.hubblesite.org/hu/db/2004/29/videos/d/stills/3/image.jpg

““What happens after death”What happens after death”

It either becomes a:It either becomes a:Black hole Black hole

or a or a Neutron star.Neutron star.

http://dante.physics.montana.edu/ns_interior.jpg

““Black Hole”Black Hole”

http://www.wvp-consulting.com/astronomy/images/blackhole.jpg

ObservationsObservations::

Used the Lick Nickel 40 Used the Lick Nickel 40 inch telescopeinch telescopeObserved remotely with Observed remotely with the help of Elinor Gates the help of Elinor Gates Took images of 4 open Took images of 4 open clustersclusters



http://www.ucolick.org/graphics/nickel_lg.jpg

CCDs:CCDs: Basic tools of astronomical Basic tools of astronomical

imaging imaging Grids of light bucketsGrids of light buckets Colorblind Colorblind 3 different filters allow us 3 different filters allow us

to see color (red, green, to see color (red, green, and blue)and blue)

Same as the digital Same as the digital cameras that you may owncameras that you may own



Isochrones:Isochrones:

““Freeze Freeze frame” of a frame” of a clustercluster

Reveals age Reveals age of clusterof cluster

Made by Made by computercomputer

X=color and temp.

Y=brightness

Which Isochrone Matches the CMD?A.

This one! Correct! :)

B.

(CMD) (ISOCHRONE)

d=10d=100.2 ( m-M+5-Ar )0.2 ( m-M+5-Ar )

How to calculate the distance:

Distance

Apparent Mag.

Absolute Mag.

Due to dust

(from CMD)

(from isochrone)





i



M11 M11

Color MagnitudeColor Magnitude DiagramDiagram

• 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 earth1.6 billion years old

My Color My Color Magnitude Magnitude DiagramDiagram

Open Cluster

NGC6939

NGC 6819NGC 6819Apparent Diameter: 5 arc min.Apparent Diameter: 5 arc min.

““NGC 6819”NGC 6819”Open star clusterOpen 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”Isochrone” “CMD” for NGC 6819 for NGC 6819

NGC 6791NGC 6791 Observed and Observed and

recorded data for recorded data for NGC 6791NGC 6791

7.6 billion years old7.6 billion years old Looking at Looking at

isochronesisochrones 4972 parsecs (3.26 4972 parsecs (3.26

light years = 1 light years = 1 parsec)parsec)

IsochronesIsochrones

Puzzles from NGC 6791Puzzles from NGC 6791 It’s really oldIt’s really old Metal richMetal rich

Sun

NGC 6819

NGC 6791

NGC 6939

NGC 6705

We would like to thank:We would like to thank:CFAOCFAOLaura Chomiuk Laura Chomiuk Kathy CookseyKathy CookseyDaisy Corral Daisy Corral Liz EspinozaLiz EspinozaEmily FreelandEmily FreelandElinor GateElinor Gate

•John MartinJohn Martin•Hilary O’BryanHilary O’Bryan•Jay StraderJay Strader•Gene SwitkesGene Switkes•Vay HoangVay Hoang

Open Clusters

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