A Stellar Pas de Trois: Dynamics of Triple Systems in Common Envelopes
Alejandra Meza (2027) | Physics and Astrophysics
Alejandra Meza is a SURF L&S scholarship recipient and a third-year Physics and Astrophysics major. For her SURF project this summer, Alejandra is studying the dynamics of triple star systems in which a binary pair is engulfed within the expanding gaseous envelope of a dying star. Motivated by gravitational-wave observations from binary mergers, her research explores how these complex interactions can lead to high-energy transients with both gravitational and electromagnetic signals, helping to better understand the formation pathways of such events.
What made you choose this research project? How did your interest in your research topic emerge?
My research interests lie in high-energy astrophysics on the frontier between observation and computation. It is an exciting time in the subfield, as detections of high-energy astrophysical events, including those observed via gravitational waves, are increasing. Binary mergers are a known source of high-energy transient phenomena and are theorized to produce an electromagnetic signature if occurring in gas. My quest to better understand the stories behind these observed transient signatures led me to this project where I am simulating a triple common envelope event to find energetic signatures from a binary merger in gas.
What is your project about? How does it relate to issues or ideas you have been studying in your coursework?
My work this summer will be a continuation of my ongoing research with astrophysicists at UC Santa Cruz, initiating a research collaboration at UC Berkeley with theoretical astrophysicist Professor Wenbin Lu. I am exploring how the evolution of triple systems in which a binary is embedded within the gas-filled envelope of an aging single star can lead to highly energetic transient signatures with electromagnetic counterparts. The post-main sequence expansion of the single star leads to the engulfment of the binary, creating a dense gaseous envelope around the orbiting objects and initiating a common envelope event.
Depending on the system’s properties, the binary may merge within the envelope, survive as a tighter pair, or be disrupted, leading to a three-body interaction with the core. These interactions could produce thermonuclear explosions if white dwarfs are involved, or accretion-powered transients if black holes or neutron stars are involved, potentially generating gravitational-wave signals with electromagnetic counterparts. A key question is whether collisions occur while the envelope is still present, which could surround the transients with hydrogen-rich material and influence their observational signatures. Studying the evolutionary pathways of triple systems provides an organic pathway to expand our understanding of common envelope evolution in higher order systems as well as the formation channels of observed high-energy transients.
What are you most excited about this summer? Will your research entail travel, access to special collections, or experiments?
I am excited to engage with the SURF community, learn from its diverse perspectives, and contribute my insights on high-energy astrophysics and the evolution of triple systems. I look forward to furthering my research on the evolution of three body systems under the mentorship of Professor Wenbin Lu.
What do you hope to learn from this experience? What would success look like for you? What challenges do you anticipate confronting?
SURF offers the opportunity to grow my research skills and approach to scientific collaboration at UC Berkeley, combining access to a top astrophysics program with a supportive mentorship network, preparing me for graduate school and beyond. I aim to leverage the mentoring available this summer to advance the depth and impact of my research, fostering a greater sense of academic belonging as a student and researcher. Furthering my research at UC Berkeley will deepen the scientific rigor of my work and support the development of theories grounded in both observation and computation.
I am excited to engage with the challenges presented by my research. One central challenge I anticipate is finding the physical parameters to keep the gas-filled envelope of the massive star from becoming ejected during the energetic interaction between the three objects. Triple systems are inherently chaotic, and the evolution of a binary embedded in the envelope of an aging single star can produce a wide range of outcomes. The interactions among the three bodies can lead to mergers, collisions, or the ejection of one of the stars, with each outcome occurring with different probabilities. This scenario is rare but highly significant because it can produce observable high-energy transients, gravitational wave events with electromagnetic counterparts, or other unusual astrophysical phenomena.
What do you hope comes out of this research? What impact do you hope your research will have?
Common envelope evolution has primarily been studied as a binary evolution problem. Studying this phenomena in the context of binary-single interactions provides an alternative theoretical basis for observed GW signatures and their electromagnetic counterparts in compact binary systems, contributing to our understanding of common envelope evolution in higher order systems. I expect to continue my research into the academic year, writing up my results, and producing a paper I will seek to publish. I hope my research will ultimately provide a new theoretical framework that links observed transient signatures to the dynamics of triple systems.