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Overview

Hubble Telescope Analysis of H II Regions and Planetary Nebulae Aaron Svoboda – The University of Northern Colorado Robert Rubin – NASA Ames Research Center. Overview. Background - H[II] Regions and Planetary Nebulae The Science Involved Our Work- Reduction and Analysis of Hubble Data

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Overview

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  1. Hubble Telescope Analysis ofH II Regions and Planetary NebulaeAaron Svoboda – The University of Northern ColoradoRobert Rubin – NASA Ames Research Center

  2. Overview • Background - H[II] Regions and Planetary Nebulae • The Science Involved • Our Work- Reduction and Analysis of Hubble Data • Conclusion

  3. H II Regions • H[II] refers to singly ionized hydrogen • The “birthplace” of stars • Central star emits ionizing radiation • Plasma is created through photoionization

  4. Orion Nebula • Stromgren Radius • Proplyd

  5. Planetary Nebula • Results from a dying star with leftover mass < 1.4 solar masses • Former Red Giant • White Dwarf star emits ionizing radiation • Plasma is created through photoionization

  6. NGC 6210 “The Turtle Nebula”

  7. NGC 6818 “The Zorro Nebula”

  8. NGC 2022

  9. More than Just Pretty Pictures • Measure electron and ion temperature • Calculate chemical abundances • Observing emission lines

  10. WFPC2 Wide Field Planetary Camera High spatial coverage-Low dispersal resolution STIS Space Telescope and Imaging Spectrograph Low spatial coverage-High dispersal resolution Hubble Space Telescope Spectrographic Instruments:Acronyms Are Our Friends!!

  11. Orion Nebula

  12. “Saturn” Nebula

  13. Notation • Line number refers to the wavelength of the emission line in Angstroms • 5008 refers to a line with wavelength 5,008 Angstroms or 500.8 nanometers

  14. Checking Instrumental Accuracy • Take the ratio of the 5008 to 4960 emission lines • Due to electron transitions from the same upper energy level • Ratio is independent of gas temperature • Theoretically shown to be 2.984 • Experimentally found to be 3.008 • Error due to scattering

  15. Electron Temperature vs. Position along the STIS slit The electron temperature is calculated using the ratio of the 5008 to 4364 emission lines

  16. Electron Temperature overlaid on WFPC2 Image

  17. Average Temperature To- Average Electron Temp. Te- Local Electron Temp. Ne - Ionic Electron Density Ni - Volumetric Ion Density

  18. Average Electron Temperature vs. Radius

  19. Mean-Squared Electron Temperature Variation To- Average Electron Temp. Te- Local Electron Temp. Ne - Ionic Electron Density Ni - Volumetric Ion Density

  20. Mean-Squared Electron Temperature Variation vs. Radius

  21. Results and Conclusions • Average temperature of O[III] is 10,146 K • Mean-squared electron temperature variation is .0036 • Temperature across nebula found to range from 9,000 to 11,000 K

  22. Why Do We Care? • Provide insight into the evolution of nebulae • Discrepancy between chemical abundances deduced from observation of lines that are collisionally excited compared with those that are due to recombination • Large temperature variations across the nebula may explain why observations do not match theory

  23. What’s Next? • Density analysis • Analysis of NGC 1976 (Orion Nebula) • Find consistencies and contradictions in the data

  24. Acknowledgements I would like to express my deepest appreciation to Dr. Robert Rubin, Naman Bhatt, and Erik Shimshock as well as all of the physics faculty at UNC for making this research experience possible.

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