Astronomy/Astrophysics

• Discovered the companion star in He3-1357 (the Stingray Nebula)
• Obtained the first spatially resolved images of the Stingray Nebula showing, more clearly than ever before seen, the collimation mechanism producing bipolar outflows
• Obtained the first visual image of Mira B (the companion star to Omicron Ceti)
  
• Calculated the Stingray Nebula's radius, expansion age, ionized mass, core mass and luminosity
• Imaged the inner torus surrounding the post-AGB star He3-1475, and measured extremely high velocities in its jets
• Developed a self-consistent model for He3-1475, showing that it links OH/IR stars having extreme outflow velocities with highly bipolar planetary nebulae
• Obtained the first spatially-resolved images of the planetary nebula M 1-58
• Discovered the torus and other circumstellar matter in the planetary nebula Hu 2-1
• Imaged the proto-planetary nebula IRAS 17441-2411, showing bipolar lobes on either side of a circumstellar disk
• Produced numerical hydrodynamic models of planetary nebulae with a variety of initial conditions
  • Demonstrated the progression of H₂ dissociation during the earliest stages of nebular evolution
  • Showed how nebular velocity, density, fractional ionization, and fraction of gas in molecules vary with time
  • Demonstrated the development of linear and non-linear v-r relations
  • Showed how the brightness of a planetary nebula varies over time during the early evolutionary stages
  • Demonstrated the development of doubly-peaked radial density profiles
  • Derived model emission-line profiles; showed how single-, double-, and triple-peaked profiles can be produced; showed how both sharply-peaked and flat-topped profiles can occur
  • Demonstrated pitfalls when interpreting emission-line profiles, particularly when determining expansion velocities
• Showed that H-alpha and microwave subflares could be caused by a distant solar flare (at the remote footpoint of a magnetic loop)
• Showed that 5 GHz solar radio bursts are co-spatial with hard x-ray bursts (suggesting repeated accelerations of electrons within the same magnetic trap)
• Detected polarization changes for successive radio bursts (indicating variations in the magnetic field geometry)
• Showed that almost all solar regions having reduced microwave emission lie along magnetic neutral lines and are highly correlated with Ha filaments
• Made radio observations that ruled out coronal density reductions as the explanation for solar filaments
• Detected time-variation of solar filaments on 1-day time scales
• Determined the height on the sun of a region of reduced microwave emission
  • Showed the height to be compatible with the bremsstrahlung absorption model
  • Showed the height to be incompatible with a cavity model or a hot filament model

Astrodynamics

• Showed that, for NASA's Tracking and Data Relay Satellites (TDRS), the solar reflectivity parameter, CR, varies seasonally due to the changing declination of the sun
• Determined the minimum quantity of tracking data needed for an accurate determination of the TDRS orbital elements
• Predicted the orbital decay and re-entry of the ISEE-1 and ISEE-2 spacecraft, showing the cause to be primarily lunar third-body perturbations

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