Madisen Johnson

Research

H₂ Formation and Destruction

Research Advisor: Dr. Blakesley Burkhart (Rutgers University)

Molecular hydrogen plays an important role in the formation and evolution of stars and galaxies. The star formation rate is strongly linked to with molecular hydrogen but it has not been determined whether this star formation is trigged by the cooling of gases through formation of molecular hydrogen or if self-gravitation occurs before cooling takes place. In order to answer these questions, further observations of the HI to H₂ transition are needed to understand the relationship between the formation and destruction rates of molecular hydrogen and the star formation rate. We are currently using the simulation of the Clouds of Theseus (Jefferson et al. 2021) to investigate these mysteries.

Cold HI in the Interstellar Medium

Research Advisors: Dr. Snezana Stanimirovic (University of Wisconsin-Madison) and Dr. Min-Young Lee (Korean Astronomy and Space Science Institute)

Molecular clouds and the populations of stars they form are important to the formation and evolution of galaxies. Molecular clouds from out of the surrounding diffuse interstellar medium (ISM) through the transition of atomic hydrogen (HI) to molecular hydrogen (H₂). In this process the cold atomic gas, also known as the Cold Neutral Medium (CNM) plays a particularly important role due to its ability to efficiently sheild and form molecular gas. To investigate the properties of the cold HI gas in and around molecular clouds we employ the use of the TIGRESS simulation (Kim & Ostriker 2017).

Solar Wind Helium Abundance

Research Advisor: Dr. Yeimy Rivera (Harvard-Smithsonian Center for Astrophysics)

Properties of minor ions, like He²⁺⁺, in the solar wind are imprinted with properties of source regions on the sun as well as mechanisms connected to heating and acceleration of the solar wind. This makes them sensitive markers of the solar wind's origin and formation at the sun. Using the Solar Probe Cup on the Parker Solar Probe (the closest we have ever been to the sun!), a detailed analysis of particle velocity distribution functions can help to investigate periods where significant and persistent helium peaks are observed to determine distinctive characteristics of the solar wind during these periods.