Flavors of Light

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Flavors of Light
your new friends R I V U X G. and R O
Y G. B I V (ROY G. BIV is RIVUX G.s little
brother.)
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The Electromagnetic Spectrum
1 micron
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Flavors of Light
RADIO radio, TV cellphones microwaves cool
clouds microwave background SETI lots H2O, O2
INFRARED heat snakes YOU! star formation cool
stars planets emit some H2O, CO2 CH4, CFCs
VISIBLE human eyes Sun normal
stars galaxies planets reflect lots O2 (a
little) asphalt absorbs
UV tan hot stars corona ISM none O3
X-RAY imaging neutron stars black
holes AGN IGM none O3
GAMMA nuclear power bombs same
as X-rays supernovae bursters none O3
familiar astronomical reach
Earth? blockers
wavelength increases LEFT frequency
increases RIGHT energy increases RIGHT
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Atmospheric Windows
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Which Wavelength? What Science?
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Telescopes
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Ground Observatories

• desired attributes of good observatories
• 1. dark avoid light pollution
• 2. dry avoid clouds, rain, snow
• 3. high avoid atmosphere
• 4. stable atm reduce turbulence
• world-class observatories
• North America Hawaii, Arizona,
  California
• South America Chile
• Africa South Africa
• Australia outback
• Antarctica South Pole
• (Europe) Canary Islands (off coast of
  Africa)
• Asia Japan
  (radio)

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Basic Light Equations
speed of light equation c ? ? ? is the
wavelength (Å, nm, microns, m, km) ? is the
frequency (Hertz Hz cycles/sec) photon
energy equation E h? energy constant X
frequency telescope resolution equation res
0.25 ? / D res is the resolution in arcseconds ?
is the wavelength in microns D is the telescope
diameter in meters
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Astronomical Measurements
want to know measurement units answer
is Astrometry distance parallax arcsec parsecs
speed (across) proper motion arcsec/yr km/sec
( dist) masses orbits years,
arcsec M? associations proper
motion arcsec/yr members Photometry flux brightn
ess magnitude watts/m2Hz luminosity brightness
mag dist watts temperature brightnesses magni
tudes K eclipses, spots, weather changing
mag yes or no Spectroscopy temperature spectrum p
hotons vs ? K composition spectral
lines photons vs ? yes or no abundance line
widths photons vs ? fractions speed
(in/out) line shifts photons vs ? km/sec
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Measuring Stars with Astrometry
Astrometry is measuring the position of light
sources. proper motion parallax
orbital motion
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Astronomical Measurements
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Parallaxes CTIOPI
Cerro Tololo Inter-american Observatory Parallax
Investigation
NOAO Surveys Program AUG 99 to JAN 03 SMARTS
1 Consortium FEB 03 to DEC 05 SMARTS 2
Consortium JAN 06 to JAN 09
1.5m OPT spectroscopy IR imaging survey
1.3m OPT/IR imaging
1.0m OPT imaging 0.9m
OPT imaging astrometry
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CTIOPI 0.9m Astrometry
Field/Scale 6.8' field at 401
mas/pixel Targets red, white, brown
dwarfs Brightness VRI from 9 to 19 Phase I
175 targets Phase II 202 targets Phase
III 102 targets (as of 26 JAN 2009) 479
total Precision I 2.24 mas for first 73
p Precision II 1.59 mas for latest 76 p
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Proxima Centauri Field
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Proxima Movie
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Proxima Centauri Parallax
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Questions about Jao et al. 2005
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