Infrared Astronomy and Activities

1
Invisible Waves

• Infrared Astronomy and Activities
• Dan Burns
• Los Gatos High School
• Lawrence Livermore National Lab
• dburns_at_lgsuhsd.org

2
Overview

• What is Infrared Radiation (IR)?
• Discovery of IR
• IR Astronomy
• IR Observatories
• Classroom Activities

NASA/JPL-Caltech
3
IR Characteristics

• IR is bounded by Visible Light and Microwave
  Radiation
• Wavelengths from about 0.7 to 350 microns
• Primary Source is Thermal Radiation
• Humans can sense it with nerves in skin
• Snakes can see IR with Pits (Pit Vipers)

NASA/JPL-Caltech
4
Thermal Radiation

• Emitted by materials with relatively strong
  molecular or atomic bonds (ie solids and liquids)
• Every object with a T gt 0 K emits thermal
  radiation
• Produced by random motions of charged particles
• Radiation peak, usually in IR, can be used to
  determine temperature

NASA/JPL-Caltech
NASA/JPL-Caltech
NASA/JPL-Caltech
5
William Herschel

• German Immigrant to England
• Discovered Uranus in 1781
• Catalogued Night Sky with Sister Caroline
• Discovered IR in 1800

NASA/JPL-Caltech
6
Herschels IR Experiment

• Investigated heat of colors in spectrum
• Temperature increased from violet to red
• Placed a thermometer beyond red, this measured
  greatest temperature increase

http//www.sciencemuseum.org.uk/on-line/treasure/o
bjects/1876-565.asp
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Student Herschel Experiment
NASA/JPL-Caltech

• Materials Copy Paper Box, Smaller Box, White
  Paper, Tape, Equilateral Glass Prism, Black
  Paint, Timer, 3 Thermometers, Sunlight!
• Time Required 30 minutes

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Equipment Setup
NASA/JPL-Caltech
NASA/JPL-Caltech

• Paint Thermometer Bulbs Black
• Trim and Tape Thermometers Close Together
• Cut Opening for Prism and Mount it
• Tape White Sheet of Paper to Bottom of box

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Procedure Outline
NASA/JPL-Caltech
NASA/JPL-Caltech
NASA/JPL-Caltech

• Position Box and Prism so Spectrum Shows
• Record Shade Temperature
• Place Thermometers, 1 each in Blue, Yellow, and
  IR
• Record Temperatures at 1 minute intervals for 5
  minutes

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Typical Results
NASA/JPL-Caltech
11
Why Infrared Astronomy?

• Almost Everything Emits IR
• IR Passes Through Dust
• Exoplanets Easier to Detect in IR
• Distant Objects Visible Light Redshifted
• Important Molecular Spectra in IR

Credit ESA/ISO, SWS, A.F.M. Moorwood
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IR Reveals the Invisible
NASA/JPL-Caltech
Interstellar Dust Emits IR
13
Spitzer Shows a Warped Sombrero Galaxy
http//www.spitzer.caltech.edu/Media/mediaimages/i
ndex.shtml
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Spitzer Reveals Stars and the Galloping Ghoul
http//www.spitzer.caltech.edu/Media/mediaimages/i
ndex.shtml
15
IR Uncovers What is Hidden
Visible
Spitzer Space Telescope Reveals Star Formation in
DR21
IR
NASA/JPL-Caltech
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Spitzer Zooms into the Triffid Nebula
http//www.spitzer.caltech.edu/Media/mediaimages/i
ndex.shtml
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IR Discovers Dim Objects
UK IR Telescope Discovers Brown Dwarfs and
Potential Free-Floating Planets in Orion
Image courtesy of the U.K. Infrared Telescope,
Mauna Kea Observatory, Hawaii
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IR Detects Distant Objects
Visible Light from Very Distant Galaxies is
Redshifted to IR
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Important Molecular Spectral Lines are in IR
IR Space Observatory Reveals Water Molecules
being Produced in Orion Nebula
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Spitzer Detects Structures in Polycyclic Aromatic
Hydrocarbon Dust
http//www.spitzer.caltech.edu/Media/mediaimages/i
ndex.shtml
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Detecting IR

• Near, Mid, and Far IR
• Atmospheric Absorption
• IR Observatories

NASA/JPL-Caltech
Image courtesy of the U.K. Infrared Telescope,
Mauna Kea Observatory, Hawaii
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Near, Mid, and Far IR Bands
NASA/JPL-Caltech
Visible
Near
Mid
NASA/JPL-Caltech
23
Atmosphere Impedes IR Observation

• Water Vapor Absorbs Some IR Wavelengths
• Atmosphere Emits its own IR Radiation

NASA/JPL-Caltech
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Past, Present, and Future IR Observatories
HST
ESA Herschel
NASA/STScI
IRAS
NASA/JPL-Caltech
Infrared Processing and Analysis Center,
Caltech/JPL. IPAC is NASA's Infrared Astrophysics
Data Center
SST
UKIRT
NASA/JWST
Image courtesy of the U.K. Infrared Telescope,
Mauna Kea Observatory, Hawaii
SOFIA
NASA/USRA
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Student Activities

• Herschel Experiment
• IR Photo Album
• Solar Cell IR Detector
• Near IR Digital Camera
• IR Detection Cards
• Red Tide Spectrometer with LabQuest

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IR Photo Album Resources

• http//spaceplace.jpl.nasa.gov/en/kids/sirtf1/sirt
  f_action.shtml for activity

27
Herschel Experiment Resources

• http//coolcosmos.ipac.caltech.edu/cosmic_classroo
  m/classroom_activities/herschel_experiment.html
  for detailed activity
• www.sciencekit.com for prism (catalog 3038400
  8.95) and thermometers (catalog 6638910 13.25
  for 10-Pack)

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Solar Cell IR Detector Resources

• www.radioshack.com for Mini Audio Amplifier
  (Catalog 2771008 14.99), Solar Cell (Catalog
  277-1201 13.99),
• 6 Cable (Catalog 42-2420 3.29)
• http//www.sofia.usra.edu/Edu/materials/activeAstr
  onomy/activeAstronomy.html for detailed activity
  information

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Near IR Digital Camera

• Webcams, Digital Cameras, or Camcorders
• Remove IR Blocking Filter from CCD
• Install IR only pass filter (Wratten 87c, exposed
  color negative, or floppy disk)
• Reassemble and view the world in Near IR

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IR Filter Spectral Characteristics
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IR Detection Cards

• 2 Types of Materials can Produce Visible Light
  When Exposed to IR from a Remote Control
• Anti-Stokes Material Absorbs 2 or More Photons
  for Every Visible Photon Emitted
• Phosphorescent Material Must be Exposed to
  Visible Light First
• See Activity from KSU Physics Education Group

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Anti-Stokes Model
Phosphorescent Model
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Red Tide Spectrometer

• Red Tide Spectrometer by PASCO and Vernier
• Educational Model made by Ocean Optics
• Automatically reads the wavelength calibration
  coefficients of the spectrometer and configures
  operating software
• USB to PC or Mac interface no external power
  requirements
• The Red Tide starts at 1049

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California Science Standards

• Earth Science 2d Students know that stars differ
  in their life cycles and that visual, radio, and
  X-ray telescopes may be used to collect data that
  reveal those differences.
• Physics 4e Students know radio waves, light, and
  X-rays are different wavelength bands in the
  spectrum of electromagnetic waves.
• Chemistry 1i, 1j Students know the experimental
  basis for the development of the quantum theory
  of atomic structure and the historical importance
  of the Bohr model of the atom. Students know that
  spectral lines are the result of transitions of
  electrons between energy levels and that these
  lines correspond to photons with a frequency
  related hv). to the energy spacing between levels
  by using Plancks relationship