Sabrina Marbut Appel

About Me

As of September 2024, I am an NSF Astronomy and Astrophysics Postdoctoral Fellow, hosted at the American Museum of Natural History. As an NSF Fellow, I am working on understanding star cluster formation and evolution using simulations, with a focus on the role of protostellar jet feedback. I use the simulation framework Torch, which bridges MHD, N-body, and stellar evolution codes through AMUSE.

I completed my PhD thesis in the summer of 2024 at Rutgers University. While at Rutgers, I worked with Prof. Blakesley Burkhart on understanding and developing analytic models of star formation. My graduate work focused on comparing simulations of star-forming regions to analytic models of star formation and included analyzing existing simulation data, running new simulations, and working on code development.

You can read more about my current and past research under the research tab or take a look at my CV here.

In addition to my research, I am dedicated to making the field of astronomy a welcoming and supportive community. During my time as a graduate student at Rutgers, I was significantly involved with the Rutgers Minorities in Physics and Astronomy (MiPA) group at Rutgers, including serving as an officer of the group for multiple years. As a graudate student, I also served as a TA for multiple undergraduate courses, and mentored an undergraduate researcher. You can read about my service and outreach work here and about my current and previous teaching and mentoring work here.

I grew up in Salem, Oregon and recieved an International Baccalaureate (IB) diploma from South Salem High School in 2013. I graduated with a B.A. in Physics from Reed College in May 2017 where I also took extensive coursework in English literature and danced as often as I could. I grew up around horses and I love the mountains! I have been dancing (including ballet and Irish dance) for most of my life. In my free time, I love to play the flute, bake, and knit, and I am a voracious reader, especially of science fiction and fantasy.

How to contact me:

You can email me at sappel at amnh.org. If for some reason that is unsuccessful, you can also reach me at sabrina.m.appel at gmail.com.

My ORCID is here: https://orcid.org/0000-0002-6593-3800

And you can find me on github as SabrinaAppel:
• GitHub

Research

Modeling Star Formation

My current research is focused on understanding star formation and how it is influenced by various physical processes. In particular, my work compares simulations of star-forming regions to analytic models of star formation. I am especially interested in the impact of different stellar feedback processes, such as protostellar outflows. My work includes analyzing existing simulation data, running new simulations, and code development for star formation simulations.

The following are a series of projection plots from the simulations used in our 2022 paper (Appel et al. 2022).

Movies of some of these simulations, as well as new versions of the simulations, can be found here.

Protostellar Jets in Torch

Over the last few years, I have developed a new module for implementing protostellar jets in Torch. Torch is a numerical framework that is optimized for simulating the formation of star clusters from the initial collapse of dense gas through gas expulsion and late stage cluster evolution (Wall et al.2019, 2020). Previous work with Torch has included various modes of stellar feedback, but not protostellar jets (e.g.,Cournoyer-Cloutier et al. 2023). By developing a new module to include protostellar jets, I can use Torch to explore the role of protostellar jets in star cluster formation and evolution.

Publications

† - indicates an undergraduate student mentee

Polak, B., Mac Low, M.-M., Klessen, R. S., Teh, J. W., Cournoyer-Cloutier, C., Andersson, E. P., Appel, S. M., Tran, A., Lewis, S. C., Wilhelm, M. J. C., Portegies Zwart, S., Glover, S. C. O., Wang, L., McMillan, S. L. W., "Massive Star Cluster Formation I. High Star Formation Efficiency While Resolving Feedback of Individual Stars", 2023, arXiv e-prints, arXiv:2312.06509, doi: 10.48550/arXiv.2312.06509

† Kiihne, A., Appel, S. M., Burkhart, B., Semenov, V. A., Federrath, C.,"Fitting Probability Distribution Functions in Turbulent Star-Forming Molecular Clouds", 2023, arXiv e-prints, arXiv:2305.11218, doi: 10.48550/arXiv.2305.11218

Appel, S. M., Burkhart, B., Semenov, V. A., Federrath, C., Rosen, A. L., Tan, J. C., "What Sets the Star Formation Rate of Molecular Clouds? The Density Distribution as a Fingerprint of Compression and Expansion Rates" 2023, ApJ, 954, 93, doi: 10.3847/1538-4357/ace897

Cournoyer-Cloutier, C., Sills, A., Harris, W. E., Appel, S. M., Lewis, S. C., Polak, B., Tran, A., Wilhelm, M. J. C., Mac Low, M.-M., McMillan, S. L. W., Zwart, S. P., "Early evolution and three-dimensional structure of embedded star clusters", 2023, MNRAS, 521, 1338, doi: 10.1093/mnras/stad568

Appel, S. M., Burkhart, B., Semenov, V. A., Federrath, C., Rosen, A. L., "The Effects of Magnetic Fields and Outflow Feedback on the Shape and Evolution of the Density Probability Distribution Function in Turbulent Star-forming Clouds", 2022, ApJ, 927, 75, doi: 10.3847/1538-4357/ac4be3

B. Burkhart, S. Appel, S. Bialy, J. Cho, A. J. Christensen, D. Collins, C. Federrath, D. Fielding, D. Finkbeiner, A. S. Hill, J. C. Ibanez-Mejia, M. R. Krumholz, A. Lazarian, M. Li, P. Mocz, M.-M. Mac Low, J. Naiman, S. K. N. Portillo, B. Shane, Z. Slepian, Y. Yuan, “The Catalogue for Astrophysical Turbulence Simulations (CATS)”, 2020, ApJ, 905, 14,

Service & Outreach

While I was a graudate student at Rutgers University, I was significantly involved in the Rutgers Minorities in Physics and Astronomy (MiPA) group, including serving as the Graduate Chair, President, and Past President at various points. MiPA is dedicated to furthering the interests of and developing a sense of community among members of the Rutgers Physics and Astronomy department who are underrepresented or historically marginalized in Physics and Astronomy. As a leader of MiPA, I helped to draft and implement a Charter and Code of Conduct for MiPA. I also founded the Equity and Inclusion Journal Club. Over my time with MiPA, I led or helped organize various events and initiatives.

For more about my service and outreach roles, please take a look at my CV.

Teaching & Mentoring

I believe teaching and mentoring are incredibly important and I find working with students to be deeply rewarding. As a graduate student, I served as a TA for several undergraduate courses of various levels. For instance, in the fall of 2022, I was a TA for an undergraduate Computational Astrophysics course where I helped juniors and seniors progress from the basics of coding in python to running astrophysical simulations.

In addition, I mentored an undergraduate student (now graduated!!), Avery Kiihne, on a research project investigating fitting methods for simulated column density PDFs. You can find their first paper here! For more about my previous teaching and tutoring experiences, please take a look at my CV.

CV

Click here to take a look at my CV. I will do my best to update it regularly.

This is a 3D volume rendering using yt of a protostellar jet in Torch. Over the past few years, I have developed a new module for implementing protostellar jets in the numerical framework Torch!

Disclaimer

Sabrina M. Appel is supported by the National Science Foundation under Award No. 2401740. This website includes material based on work supported by the National Science Foundation under this Award. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author (Sabrina M. Appel) and do not necessarily reflect the views of the National Science Foundation.

Contact

• GitHub

Elements

i = 0;

while (!deck.isInOrder()) {
    print 'Iteration ' + i;
    deck.shuffle();
    i++;
}

print 'It took ' + i + ' iterations to sort the deck.';