Date of Award
Master of Science (MS)
Liliana Rivera Sandoval
Juan P. Madrid
Mario C. Diaz
AM CVn systems are an exotic class of compact objects with ultra-short orbital periods, in which a primary white dwarf accretes material from a helium-rich degenerate or semi-degenerate donor. The study of these systems has implications for binary stellar evolution theory, the future low-frequency gravitational wave astronomy, and accretion physics under extreme conditions. The physical mechanism behind the anomalous energy momentum transport that explains their optical behavior is poorly understood, and the proposed models based on thermal and tidal instabilities do not accurately reproduce the observations. In this thesis, we exploit the capabilities of the Transiting Exoplanet Survey Satellite to analyze a sample of known and candidate AM CVn systems, in order to explore the impact of other mechanisms, such as enhanced mass transfer from the donor, on the variability of these systems. For the prototype, AM CVn, we have identified and characterized the time evolution of a rich spectrum of periodic signals. We identified an anticorrelation in the power between the apsidal and nodal superhumps, alternating on timescales of months. Additionally, we have detected several unexplored low-frequency signals, and we found that the positive and negative disk precession periods are among the most important photometric periodicities. Regarding the outbursting system KL Dra, we have constructed a well-sampled, long-term light curve, enabling reliable measurements of its super outburst properties, and which will be valuable for testing existing models. By combining ground-based observations, we have accurately determined the evolution of KL Dra’s recurrence time, identifying an increase compared to previous reports. In our investigation of the superhump period’s time evolution, we have found a distinct power profile pattern in the spectrogram for outbursting systems. Furthermore, we report the detection of superhump periods in one recently confirmed AM CVn and three AM CVn candidates with unknown orbital periods, which strongly suggests that the candidates belong to the AM CVn class. Additionally, we document the presence of superhumps outside of the plateau stage in two of these systems. Finally, the superhump periods in three of these systems share identical values, implying nearly identical orbital periods despite their diverse outburst behaviors, suggesting that other system parameters play a significant role in the dynamics of the accretion disk.
Salazar Manzano, Luis E., "Time-Domain Analysis of Accreting Ultra Compact White Dwarf Binaries from Continuous Space-Based Observations" (2023). Theses and Dissertations - UTRGV. 1401.
Available for download on Sunday, August 31, 2025