Date of Award
Spring 6-13-2025
Degree Type
Thesis
Degree Name
Master of Science (MS)
Department
Physics
First Advisor
Anuj Sarma, PhD
Abstract
Magnetic fields likely play an important role in star formation, yet their influence remains poorly understood due to the observational challenges in measuring them. The only direct method for measuring magnetic fields is through the Zeeman effect, the splitting of spectral lines in the presence of a magnetic field. Water masers, which trace high-density shocked regions, are known to occur throughout some of the earliest stages of the star formation process. They provide an excellent opportunity to observe the Zeeman effect. However, Zeeman detections in H2O masers have so far been limited primarily to isolated, high-intensity maser lines with simple velocity profiles. This thesis presents a study of the Zeeman effect in the star-forming region NGC 7129 FIRS2, which hosts water masers with velocity-blended components. Two maser spots were observed toward this source; they were designated as maser A and B. Maser A was fit with four Gaussian components, and maser B with two Gaussian components. Statistically significant Zeeman detections were made in three of the four components of maser A and one component of maser B. These detections yielded significant line-of-sight magnetic fields of 26-66 mG, well within the range of fields detected in H2O masers. Using an empirical relation from the literature for field strength vs. density, and under the assumption that the field is amplified in proportion to the gas density, we conclude that the post-shock particle density behind the outflows in NGC 7129 FIRS2 is 108 cm−3, in agreement with models that predict that H2O masers are excited in gas with densities 108-109 cm−3. We also find that the shock velocities in this region are well over 30-50 km s−1, and conclude that the outflows from the protostar in NGC 7129 FIRS2 are causing fast, discontinuous, J-shocks. Finally, we find that the magnetic energy density dominates over the kinetic energy density by at least an order of magnitude, indicating that the fields are likely playing a dynamically significant role in regulating the outflows in this star-forming region. We conclude that even though the detection of the Zeeman effect in velocity-blended maser spectral line profiles is challenging, we can still obtain reliable magnetic field measurements that can be used to evaluate the role of the magnetic field in star-forming regions.
Recommended Citation
Beltran, Marina Bethann, "ZEEMAN EFFECT OBSERVATIONS OF WATER MASERS IN THE STAR FORMING REGION NGC 7129 FIRS2" (2025). College of Science and Health Theses and Dissertations. 569.
https://via.library.depaul.edu/csh_etd/569
SLP Collection
no