Infrared Astronomy and Activities Dan Burns Los Gatos High School Lawrence Livermore National Lab [email protected]

Infrared Astronomy and Activities

Dan Burns

Los Gatos High School

Lawrence Livermore National Lab

[email protected]

http://education.llnl.gov/academies/?page=home

Overview

• What is Infrared Radiation (IR)?

• Discovery of IR

• IR Astronomy

• IR Observatories

• Classroom Activities

NASA/JPL-Caltech

• 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)

IR Characteristics

NASA/JPL-Caltech

Thermal Radiation• Emitted by materials with relatively strong molecular

or atomic bonds (ie solids and liquids)

• Every object with a T > 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-CaltechNASA/JPL-Caltech

William Herschel

• German Immigrant to England

• Discovered Uranus in 1781

• Catalogued Night Sky with Sister Caroline

• Discovered IR in 1800

NASA/JPL-Caltech

Herschel’s 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/objects/1876-565.asp

Student Herschel Experiment

• Materials: Copy Paper Box, Smaller Box, White Paper, Tape, Equilateral Glass Prism, Black Paint, Timer, 3 Thermometers, Sunlight!

• Time Required: ~ 30 minutes

NASA/JPL-Caltech

Equipment Setup

• 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

NASA/JPL-CaltechNASA/JPL-Caltech

Procedure Outline

• 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

NASA/JPL-Caltech NASA/JPL-Caltech

NASA/JPL-Caltech

Typical Results

NASA/JPL-Caltech

Why Infrared Astronomy?• Almost Everything Emits IR

• IR Passes Through Dust

• Exoplanets Easier to Detect in IR

• Distant Object’s Visible Light Redshifted

• Important Molecular Spectra in IR

Credit: ESA/ISO, SWS, A.F.M. Moorwood

IR Reveals the Invisible

Interstellar Dust Emits IRNASA/JPL-Caltech

Spitzer Shows a Warped Sombrero Galaxy

http://www.spitzer.caltech.edu/Media/mediaimages/index.shtml

Spitzer Reveals Stars and the Galloping Ghoul


IR Uncovers What is Hidden

Spitzer Space Telescope Reveals Star Formation in DR21

Visible

IR

NASA/JPL-Caltech

Spitzer Zooms into the Triffid Nebula


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

IR Detects Distant Objects

Visible Light from Very Distant Galaxies is Redshifted to IR

Important Molecular Spectral Lines are in IR

IR Space Observatory Reveals Water Molecules being Produced in Orion Nebula

Spitzer Detects Structures in Polycyclic Aromatic Hydrocarbon Dust


Detecting IR

• Near, Mid, and Far IR

• Atmospheric Absorption

• IR Observatories

NASA/JPL-Caltech


Near, Mid, and Far IR Bands

Visible Near Mid

NASA/JPL-Caltech

NASA/JPL-Caltech

Atmosphere Impedes IR Observation• Water Vapor Absorbs Some IR Wavelengths

• Atmosphere Emits its own IR Radiation

NASA/JPL-Caltech

Past, Present, and Future IR Observatories

IRAS

HSTESA Herschel

UKIRT

SST

NASA/JWST

SOFIA

NASA/JPL-Caltech


NASA/STScI

Infrared Processing and Analysis Center, Caltech/JPL. IPAC is NASA's Infrared Astrophysics Data Center

NASA/USRA

Student Activities

• Herschel Experiment

• IR Photo Album

• Solar Cell IR Detector

• Near IR Digital Camera

• IR Detection Cards

• Red Tide Spectrometer with LabQuest

http://spaceplace.jpl.nasa.gov/en/kids/sirtf1/sirtf_action.shtml

for activity

IR Photo Album Resources

http://coolcosmos.ipac.caltech.edu/videos/more_than_your/index.html

Cool Cosmos Website

Herschel Experiment Resources

• http://coolcosmos.ipac.caltech.edu/cosmic_classroom/classroom_activities/herschel_experiment.html for detailed activity

• www.sciencekit.com for prism (catalog # WW65664M00 $8.95) and thermometers (catalog # 6638910 $13.25 for 10-Pack)

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/activeAstronomy/activeAstronomy.html for detailed activity information

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

• Sony Nightshot Camcorder has switch to remove IR blocking filter

IR Filter Spectral Characteristics

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

Anti-Stokes Model

Phosphorescent Model

Red Tide and SpectroVis Spectrometers

•Red Tide and SpectroVis Spectrometers by Vernier•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 $1732, SpectroVis at $449•Optical Fibers are extra

IR Emission from a Green Laser

• Some Green Lasers allow IR at 802 nm and 1064 nm to leak out

• If IR reflects off surfaces that pass green it can be dangerous

• This IR can be measured with a simple experiment, see below for more info:

http://www.nist.gov/customcf/get_pdf.cfm?pub_id=906138

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 Planck’s relationship

Documents

Infrared Astronomy and Activities Dan Burns Los Gatos High School Lawrence Livermore National Lab [email protected]