Is this project an undergraduate, graduate, or faculty project?
Undergraduate
Project Type
individual
Campus
Daytona Beach
Authors' Class Standing
Brianna Johnson, Senior
Lead Presenter's Name
Brianna Johnson
Lead Presenter's College
DB College of Arts and Sciences
Faculty Mentor Name
Edwin Mierkiewicz
Abstract
This project focuses on measuring the Lyman continuum photon luminosity (Lc) of diffuse H II regions using multi-line observations from the Wisconsin H-Alpha Mapper (WHAM). Previous work by Sahan & Haffner (2016) analyzed the λ Ori region in Hα, [S II], and [N II], which I build on by refining assumptions about distance, extinction, and background emission, as well as extending the analysis to additional regions such as Perseus. To define the extent of each H II region, I identify the brightest Hα beam and select surrounding beams within 0.25σ of that peak. I then applied two different approaches to estimate the emitting region. The first follows the original circular approximation used in earlier work. The second is a beam-union method that directly combines the selected WHAM beams without forcing the region into a circular shape, allowing for a more realistic representation of irregular structure and beam overlap. Applying both methods to the λ Ori region, I find Lc ≈ 7.25 × 10⁴⁸ photons s⁻¹ using the circular approach and Lc ≈ 7.79 × 10⁴⁸ photons s⁻¹ using the beam-union method. Overall, this work provides a more flexible framework for estimating ionizing photon output in non-spherical H II regions. By applying this method across multiple regions and emission lines, I aim to better constrain the role of massive stars in shaping the ionized interstellar medium.
Did this research project receive funding support (Spark, SURF, Research Abroad, Student Internal Grants, Collaborative, Climbing, or Ignite Grants) from the Office of Undergraduate Research?
No
Measuring Lyman Continuum Photon Luminosity in H II Regions
This project focuses on measuring the Lyman continuum photon luminosity (Lc) of diffuse H II regions using multi-line observations from the Wisconsin H-Alpha Mapper (WHAM). Previous work by Sahan & Haffner (2016) analyzed the λ Ori region in Hα, [S II], and [N II], which I build on by refining assumptions about distance, extinction, and background emission, as well as extending the analysis to additional regions such as Perseus. To define the extent of each H II region, I identify the brightest Hα beam and select surrounding beams within 0.25σ of that peak. I then applied two different approaches to estimate the emitting region. The first follows the original circular approximation used in earlier work. The second is a beam-union method that directly combines the selected WHAM beams without forcing the region into a circular shape, allowing for a more realistic representation of irregular structure and beam overlap. Applying both methods to the λ Ori region, I find Lc ≈ 7.25 × 10⁴⁸ photons s⁻¹ using the circular approach and Lc ≈ 7.79 × 10⁴⁸ photons s⁻¹ using the beam-union method. Overall, this work provides a more flexible framework for estimating ionizing photon output in non-spherical H II regions. By applying this method across multiple regions and emission lines, I aim to better constrain the role of massive stars in shaping the ionized interstellar medium.