The McMathPierce Solar Telescope Stellar Spectrograph

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The McMath-Pierce Solar Telescope Stellar
Spectrograph

• ESS 590 Winter 2007 Lecture

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Scientific Motivation
STIS observations of Io
Jovian System Io Plasma Torus
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Scientific Summary

• Oxygen and sulfur emission near Io
• Localized position of spots show dependence on
  orientation of Jupiters magnetic field
• Integrated intensity shows dependence on density
  of the Io plasma torus (work in progress)

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R 120,000 (?/??) at 6300 Å
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Grating basics
http//www.physicsclassroom.com/Class/light/U12L1b
.html
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Grating basics

• m ? d (sin(?i) sin(?m))

http//www.madsci.org/posts/archives/May2003/10533
50704.Ph.r.html
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Blazed grating

• Scattering surfaces are tipped at an angle to
  make scattering more efficient at a particular
  angle

http//grus.berkeley.edu/jrg/ins/node3.html
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• Stellar spectrograph echelle operated at order m
  36 for OI
• Get angular dispersion from derivative of
  diffraction angle wrt wavelenth
• High m ? high dispersion

R 120,000 (?/??) at 6300 Å
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Io OI line
Example spectrum 2002 Jan 26
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Io, Telluric and solar lines identified
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Fitting Software
3600 Io spectra, gt15,000 calibration images
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Clear Detection of Io OI Signal
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Variation in Ios OI brightness not quite where
you would expect in System III
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Why?

• Details of Ios orbit and torus

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Correlate Multiple Datasets

• STIS (when we had it)
• Ground-based torus images
• Ground-based Io OI
• Jovian aurora
• Jupiters mag field
• Spacecraft flyby
• Solar wind or jup mag field

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Cool things to do with the Io OI dataset

• Compare to Io volcanic record
• Compare to solar wind activity
• Compare to Io flux tube footprint on Jupiter
• Complement spacecraft data (a permanent in situ
  probe)
• Model of Io OI emission variation seems to work
  well assuming Io does not disturb the torus. All
  you need is a scaling factor, which does vary on
  different days

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Example Comparison 1997 Oct 14

• Increase in emission is unusually large in UV
  lines (but we dont have many observations)
• Increases like this in groundbased data are
  common
• Torus images were showing a knot in about the
  right place

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Observed Asymmetry in torus images, fall 1997
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Io OI model shows there should be a factor of
2, not 3 in brightening
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BUT that is using the old hand-reduced data

• Machine reduction with the same line list gives
  the same results

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BUT that is using the old hand-reduced data

• Machine reduction with expanded line list gives
  different results

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What does it all mean?