Alejandra Rosselli-Calderon theoretical astrophysicist

About Me Research Outreach Education Resources CV
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About me

Hi! My name is Alejandra Rosselli-Calderon and I am a Colombian-Italian astrophysics PhD student currently at the University of California, Santa Cruz (UCSC). I have a growing interest in high energy theoretical astrophysics and cosmology. I am currently working with Prof. Enrico Ramirez-Ruiz in the Astronomy and Astrophysics Department at UCSC. My recent work has focused on simulating binary and triple systems during mass transfer episodes such as Roche-lobe overflows and common envelopes.

I was previously at Brown University in Providence, RI, where I got my Master of Science in physics. I graduated with a Bachelor of Arts with highest honors in physics from Clark University in Worcester, MA, where I worked in experimental biophysics in Dr. Alexander P Petroff’s lab. As part of this lab, I studied collective dynamics of magnetotactic bacteria.

I am very passionate about diversity and social justice in STEM. I am always looking to improve my scientific communication skills through outreach, mentoring, and education classes.

I have had the incredible opportunity to be part of the Lamat institute both as a mentee and as a mentor. I deeply believe in achieving equal opportunity and access across the fields of physics and astronomy, and uplifting the voices of those who have been sidelined and ignored.

You can watch Prof. Enrico Ramirez-Ruiz, Rewa Bush and me talk about Lamat here.

Featured Projects

Star-BH

Star-Black Hole Binaries

In the realm of binary systems, I have focused on the interactions between stars and their companions as well as stars and their environments. My last work looks at binary systems comprised of a star and a stellar-mass black hole. I looked at the increase in the accretion of metals from the ISM onto the stellar companion in order to look for potential observable markers of heightened accretion. We find that old stars in binaries can potentially increase their observable metallicity from ISM accretion alone.

Read it here!
Binary BH in CE

Binaries in Common Envelope

One of my topics of interest is the interactions between stars over the course of their evolution. In this work, I look at common envelope evolution combined with stellar evolution and the dynamics of binary systems. I simulated a hierarchical triple systems by placing binary inside of a common envelope and evolving it with a hydrodynamics code (FLASH). I analyzed different stages of stellar evolution using MESA code to figure out the conditions for envelope ejection and inspiraling of a single object.

Here is the link!
Bacteria clustering

Bacterial Biophysics

As part of Dr. Alexander P Petroff’s Lab at Clark University, I studied the individual and collective dynamics of Magnetoglobus multicellularis, a species of multicellular bacteria that moves through the process of magnetotaxis. I worked on nullifying the magnetic field of the Earth by using a triaxial Helmholtz coil system, used Matlab to do video analysis of bacteria swimming and worked on developing a protocol to collect and clean samples of bacterial specimen. I compared the collective arrangement of bacteria colonies to a liquid crystal of active matter with self-assemblance.

Check it out!