Stars, Interstellar Medium and the Galaxy Commons^™

Simulations Of Magnetar Spin-Down Lifetimes Using Magnetic Braking Models, Sophie Wessel

Honors College Theses

The beginnings of magnetar lifetimes are not very well understood. It is important to improve our understanding of magnetar origins in order to investigate possible evolutionary connections to other classes of NS, such as X-ray dim isolated NSs (XDINSs). Here we follow in the steps of another paper1 in modeling the spin evolution of magnetars, utilizing two avenues of evolution: one involving exponential B-field decay, and the other involving suband super-exponential B-field decay. We replicate the results of the paper, utilizing Monte Carlo methods to generate and evolve synthetic populations of magnetars, which are then compared to the current known …

The Effect Of Nuclear Isomers On S-Process Nucleosynthesis, Jaad Tannous

All Dissertations

s-Process nucleosynthesis is a process in which stars produce elements of mass range A = 57 to 210. Since the days of B2FH, immense work has gone into quantifying and computing s-process yields and pathways. We expand upon said work along two fronts. The first front sets up the framework for proper treatment of nuclear isomers in network calculations. We apply the framework to study 85Kr, which is a pivotal isotope in the s-process chain that affects the abundance yields of Strontium and Rubidium isotopes. In particular, we are interested in the ratio of 88Sr/86Sr and 87Rb which are important …

Constraining Neutron Star Kicks Through Gravitational Wave Detection, James Phillips

Graduate Theses and Dissertations

Neutron stars have, on average, much higher proper motions than those of hot and bright O and B type main sequence stars. Thus, it is widely suspected that asymmetries in core-collapse supernovae provide a substantial kick to these compact objects at birth. Gen- eral Relativity predicts that such supernova asymmetries will generate bursts of gravitational radiation, though no such burst has been yet detected. Here we argue that the polarization amplitudes of those gravitational waves can be used to calculate the kicks imparted on that nascent neutron star. We begin by reviewing the evidence for natal kicks, then we describe …

Extraterrestrial - Why They're Almost Certainly Out There, Marcus Brown

2025 Student Academic Showcase

This was an essay I did for my English Composition II class. It’s evaluating an argument from a TED talk of my choice. The TED talk I chose for this writing project was "Extraterrestrial’s - Why They’re Almost Certainly Out There” by Chris Crowe talking about the many exoplanets out there in our universe and beyond. The presentation explains the different sizes, the atmosphere, and the number of exoplanets capable of hosting life. The statistics were used in this analysis like the amount of hydrogen dioxide on each exoplanet. I had to determine if Chris Crowe did a good job …

Contact Binary Stars: A Roadmap To Their Nature And Evolution, Larry A. Molnar

University Faculty Publications and Creative Works

Notre Dame Physics & Astronomy Dept. Seminar, March 18th, 2025 with students L. Carr, J. Darrow Former students: J. Lau, L. Henderson, A. Avery, G. M. Le, M. Blain

Rapid Mid-Infrared Spectral Timing With Jwst: Grs 1915+105 During An Mir-Bright And X-Ray-Obscured State, P. Gandhi, E.S. Borowski, J. Byrom, R.I. Hynes, T.J. Maccarone, A.W. Shaw, O.K. Adegoke, D. Altamirano, M.C. Baglio, Y. Bhargava, C.T. Britt, D.A.H. Buckley, D.J.K. Buisson, P. Casella, N. Castro Segura, P.A. Charles, J.M. Corral-Santana, V.S. Dhillon, R. Fender, A. Gurpide, C.O. Heinke, A.B. Igl, C. Knigge, S. Markoff, G. Mastroserio, M.L. Mccollough, M. Middleton, J.M. Miller, J.C.A. Miller-Jones, S.E. Motta, J.A. Paice, D.D. Pawar, R.M. Plotkin, P. Pradhan, M.E. Ressler, D.M. Russell, T.D. Russell, P. Santos-Sanz, T. Shahbaz, T. Shahbaz, G.R. Sivakoff, D. Steeghs, A.J. Tetarenko, J.A. Tomsick, F.M. Vincentelli, M. George, M. Gurwell, R. Rao

Publications

No abstract provided.

Line List For The A²Π−X²Σ⁺ And The B²Σ⁺−X²Σ⁺ Band Systems Of Caf, Léo Lavy, Peter F. Bernath, Adam Pastorek

Chemistry & Biochemistry Faculty Publications

The spectral analysis of molecule-rich asymptotic giant branch (AGB) stars is challenging. Although other calcium and fluorine bearing molecules are observed in the microwave and in the visible spectrum of AGB stars, CaF has never been detected, despite favorable chemical equilibrium predictions. Yet, measuring the CaF abundance could give more insight into the fluorine budget of AGB stars and allow better simulation of stellar spectra. In this work, we present an analysis of the visible spectrum of CaF obtained with a Fourier transform spectrometer. CaF A²Π−X²Σ⁺ and B²Σ⁺−X²Σ⁺ band systems were excited with a hollow cathode discharge. Using previous fluorescence …

Experimental Absorption Cross Sections For Zro, Léo Lavy, Peter F. Bernath, Manish Bhusal, Jacques Liévin

Chemistry & Biochemistry Faculty Publications

Absorption cross sections for ZrO are provided and can be used as a template to interpret spectra of S-type stars. The ZrO spectrum was measured in emission from a carbon furnace at 2700 K and calibrated using synthetic spectra of ⁹⁰Zr¹⁶O. A set of nearly isolated molecular lines has been used for the calibration. We also thoroughly review the literature on the spectroscopy of ZrO. Comparison of the experimental spectrum with currently available line lists revealed issues in ZrO spectral simulation. (a) Within band systems, the relative intensities are not always well reproduced. (b) We identify yet unreported band systems, …

Nonlinear Wave Dynamics In Asteroseismology With Application To Delta Scuti Stars, Mohammed Mourabit

Physics Dissertations - Archive

This thesis compiles the collection of works in nonlinear astroseismology and its implication to the δ Sct variable that we carried over the course of five years. With the advent of high-resolution space missions such as the Kepler and TESS telescopes, we were able to see significant progress in the field in recent years. Nonetheless the new technologies also brought an increasing number of observation that are seemingly contradictory to the linear theory of asteroseismology. In particular, we find the δ Sct variable, which eludes our models in terms of how varied we find they spectra for stars with very …

The Origin And Properties Of Ionized Gas In The Inner Milky Way Disk, Dylan J. Linville

Graduate Theses, Dissertations, and Problem Reports (ETD)

The interstellar medium (ISM) plays a crucial role in the evolution of the Milky Way and other spiral galaxies, but numerous gaps remain in our collective understanding of its properties. The now-complete Green Bank Telescope (GBT) Diffuse Ionized Gas Survey (GDIGS) and the ongoing extension, the GBT Diffuse Ionized Gas Survey at Low Frequencies (GDIGS-Low), offer the opportunity to study the ionized component of the ISM at unmatched sensitivity and resolution. In this dissertation I will utilize GDIGS and GDIGS-Low data to improve our understanding of discrete regions of ionized gas. I first use GDIGS to provide improved measurements of …

Stars, Statutes, And Sharing: Designing Global Ip Frameworks For Space-Based Discoveries, Ed Koellner

Marquette Intellectual Property & Innovation Law Review

As humanity stretches farther into space physically, commercially, and intellectually, contemporary legal frameworks are beginning to creak under the pressure. Intellectual property laws seem to be playing catch-up. Those laws were written for a world bound by borders and gravity, not for orbital labs, the Earth’s Moon, or AI-generated inventions drifting above the Earth.

This article takes a closer look at the increasingly complex intersection of space law, intellectual property, and artificial intelligence. This domain is no longer reserved for state-led missions or high-level treaties. Now and in the near future, a university lab or a private startup might be …

Boy Whose Head Was Filled With Stars: A Life Of Edwin Hubble (2021) By Isabelle Marinov, Maughn Rollins Gregory

Picture Books

Barely a hundred years ago, Edwin Hubble changed the way we understand the universe and our place in it more dramatically than almost anyone else has ever done. As this picture book biography shows, his mind-boggling discoveries can be traced back to childhood questions. The discovery that the world is bigger than we had imagined happens in many ways, and learning that we have some choices in deciding how new facts, new experiences, and new perspectives can matter to us is a necessary part of education.

The B³Π–A³Δ And B³Π–X¹Σ+ Band Systems Of Zro, Manish Bhusal, Peter F. Bernath, Jacques Liévin, Léo Lavy

Chemistry & Biochemistry Faculty Publications

The zirconium oxide (ZrO) b³Π–a³Δ system is a prominent source of opacity in the atmospheres of S-type stars in the near-infrared region. The emission spectra of ZrO, obtained at the National Solar Observatory located at Kitt Peak in Arizona, have been utilized to analyze this band system. A reanalysis of the 0–0 vibrational band of the b³Π–a³Δ transition has been carried out. For the first time, the vibrational bands with 1 ⩽ v ′ ⩽ 3 and v″ ≤ 4 for the same electronic transition have been rotationally analyzed using PGOPHER. Additionally, the 0–0 and 1–1 bands of the spin-forbidden …

A Time-Dependent Spectral Analysis Of Γ Cassiopeiae, Sean J. Gunderson, David P. Huenemoerder, José M. Torrejón, Dustin K. Swarm, Joy S. Nichols, Pragati Pradhan, Richard Ignace, Hans Moritz Guenther, A.M.T. Pollock, Norbert S. Schulz

Publications

We investigated the temporal and spectral features of γ Cassiopeiae’s X-ray emission within the context of the white dwarf (WD) accretion hypothesis. We find that the variabilities present in the X-ray data show two different signals, one primarily due to absorption and the other due to flickering like in nonmagnetic cataclysmic variables. We then use this two-component insight to investigate previously unreported simultaneous XMM and NuSTAR data. The results of model fitting find WD properties consistent with optical studies alongside a significant secondary, thermal source. We propose a secondary shock between the Be decretion disk and WD accretion disk as …

Archival Stellar Flare Follow-Up In Evryscope Observations, Tyler J. Thomas

Honors Undergraduate Theses

M dwarfs, the most abundant stars in the galaxy, are prime targets in the search for habitable exoplanets. However, their high flare activity may compromise planetary atmospheres, with Coronal Mass Ejections (CMEs) increasing this risk. Despite this, the relationship between M dwarf flares and CMEs is not well understood. This study uses archival data from Evryscope North and South, crossmatched with Sloan Digital Sky Survey (SDSS) and Gaia data, to investigate this relationship. This crossmatching demonstrated an abundance of stars within the 20 arcsecond Evryscope uncertainty. The analysis also revealed a modest excess of K1 and F9 type stars but …

Response Of Galactic Disks To Dark Matter Halo Triaxiality, Alex J. Hutton

College of Graduate Studies: Theses & Dissertations

In this study we examine the influence of dark matter halo triaxiality on the evolution of galactic disks. We do this by running a series of collisionless N-body models. In a first set of models we place the galactic disk within an oblate halo at various orientations and examine the resulting evolution. In our second set we construct fully self-consistent models of a stellar disk embedded within a spherical halo, with an impacting external dark matter dwarf galaxy. After evolving the simulations for a Hubble time, we examine the disk orientation and warping along with other quantities such as bar …

Classification Of Variable Stars Using Convolutional Neural Network, Abhina Premachandran Bindu

Dissertations and Theses

This research focuses on developing Convolutional Neural Networks (CNNs), for the process of classifying and identifying variable stars through the analysis of unprocessed light curves from Transiting Exoplanet Survey Satellite (TESS). As astronomical data is becoming increasingly complex, and as advanced missions deploy sophisticated instruments for data collection, both the quality and quantity of the data are improving at a rapid pace. This has created an urgent need to automate the analysis process using efficient and effective methods, such as those based on machine learning. While previous research has explored machine learning approaches, there has been limited focus on implementing …

M Star Opacities: The B³Π–X³Δ Band System Of Tio, Peter F. Bernath, Manish Bhusal, Mirek R. Schmidt

Chemistry & Biochemistry Faculty Publications

The spectra of titanium monoxide (TiO) are used to classify M stars. TiO experimental cross sections based on a high-resolution emission spectrum recorded with a Fourier transform spectrometer at the National Solar Observatory are used for the analysis of the TiO B³Π–X³Δ transition (𝛾' system). The 3–2 and 4–3 vibrational bands are analyzed for the first time, and the analysis of the 2–1 band is revised. The transition dipole moment function from an ab initio calculation is used to calculate the band strengths. These band strengths are used to produce a B³Π–X³Δ line list for the vibrational levels v' ⩽ …

Pulse-Profile Modeling And Spin–Orbit Alignment In A Suzaku Sample Of Accreting X-Ray Binary Pulsars, Silas G.T. Laycock, Rigel C. Cappallo, Pragati Pradhan, Dimitris M. Christodoulou, Biswajit Paul

Publications

We report pulse-profile modeling of a sample of 23 X-ray binary pulsars observed with the Suzaku X-ray satellite. These pulsars have spin periods ranging from 0.7 to 9400 s, and their X-ray emission is powered by the accretion from their stellar companions. We fitted each individual pulse profile with the Polestar geometric model, which accounts for X-ray emission from two hot spots modeled as a simple combination of fan+pencil beam components, including an approximation for gravitational light bending. In 14 of 21 cases, our measurements of the inclinations of the pulsar spin axes broadly agree with the corresponding inclinations of …

A Spectrum Of Light: Speculative Poetry Of Celestial Bodies And Astrophysics, Shannon Sosebee

Electronic Theses and Dissertations

This is a collection of speculative poetry with a focus on celestial objects within our solar system and larger bodies outside of our solar system, some of which are only theorized to exist. The author finishes the collection with introspective works, laying bare vulnerabilities and insecurities.

Detection Of The Orbital Modulation Of Fe Kα Fluorescence Emission In Centaurus X-3 Using The High-Resolution Spectrometer Resolve On Board Xrism, Yuto Mochizuki, Masahiro Tsujimoto, Richard L. Kelley, Bert Vander Meulen, Teruaki Enoto, Yutaro Nagai, Chris Done, Pragati Pradhan, Natalie Hell, Katja Pottschmidt, Ken Ebisawa, Ehud Behar

Publications

The Fe Kα fluorescence line emission in X-ray spectra is a powerful diagnostic tool for various astrophysical objects to reveal the distribution of cold matter around photoionizing sources. The advent of the X-ray microcalorimeter on board the XRISM satellite will bring new constraints on the emission line. We present one of the first such results for the high-mass X-ray binary Centaurus X-3, which is composed of an O-type star and a neutron star (NS). We conducted a 155 ks observation covering an entire binary orbit. A weak Fe Kα line was detected in all orbital phases at an equivalent width …

Sharp Periodic Flares And Long-Term Variability In The High-Mass X-Ray Binary Xte J1829−098 From Rxte Pca, Swift Bat, And Maxi Observations, Robin H.D. Corbet, Ralf Ballhausen, Peter A. Becker, Joel B. Coley, Felix Fuerst, Keith C. Gendreau, Sebastien Guillot, Nazma Islam, Gaurava Kumar Jaisawal, Peter Jenke, Peter Kretschmar, Alexander Lange, Christian Malacaria, Mason Ng, Katja Pottschmidt, Pragati Pradhan, Paul S. Ray, Richard E. Rothschild, Philipp Thalhammer, Lee J. Townsend, Joern Wilms, Colleen A. Wilson-Hodge, Michael T. Wolff

Publications

XTE J1829−098 is a transient X-ray pulsar with a period of ∼7.8 s. It is a candidate Be star system, although the evidence for this is not yet definitive. We investigated the twenty-year-long X-ray light curve using the Rossi X-ray Timing Explorer Proportional Counter Array (PCA), Neil Gehrels Swift Observatory Burst Alert Telescope, and the Monitor of All-sky X-ray Image. We find that all three light curves are clearly modulated on the ∼244 days orbital period previously reported from PCA monitoring observations, with outbursts confined to a narrow phase range. The light curves also show that XTE J1829−098 was in …

Constraining Accreted Neutron Star Crust Shallow Heating With The Inferred Depth Of Carbon Ignition In X-Ray Superbursts, Zachary P. Meisel

Faculty Publications

Evidence has accumulated for an as-yet unaccounted for source of heat located at shallow depths within the accreted neutron star crust. However, the nature of this heat source is unknown. I demonstrate that the inferred depth of carbon ignition in X-ray superbursts can be used as an additional constraint for the magnitude and depth of shallow heating. The inferred shallow heating properties are relatively insensitive to the assumed crust composition and carbon fusion reaction rate. For low-accretion rates, the results are weakly dependent on the duration of the accretion outburst, so long as accretion has ensued for enough time to …

Exploring The Structure Of Space Science Research In Mexico Using Science Mapping Tool: Citespace., Ibis Anette Moreno-Lozano, Humberto Carrillo-Calvet, Jose Luis Jiménez-Andrade, Ricardo Arencibia-Jorge

UTA Libraries Staff Publications - Archive

This paper presents an analysis of the knowledge structure of the Mexican scientific community in the field of Space Science in Web of Science, between 2000 and 2019. CiteSpace software helped to identify the influential papers in the domain. The findings of this study shed light on the historical development of Space Science in Mexico and highlight the country's scientific performance with the worldwide trend. Moreover, the study emphasized the importance of bibliometrics in understanding the scientific undercurrents of a discipline. By analyzing co-citation networks, the study identified prominent clusters and research fronts in the field, providing valuable insights into …

From Stars To Moons: Investigating Stellar Rotations, Planetary Interactions, And Exoplanetary Prospects, Rosario Cecilio-Flores-Elie

Dissertations, Theses, and Capstone Projects

The thesis is divided into two key sections. The first chapter presents the results of analyzing TESS light curves for 99 targets within the Carina-Near moving group. By deriving rotational periods, this analysis supports stellar age estimation, contributing to the broader efforts of the Backyard Worlds: Planet 9 citizen project in determining age parameters for 89 newly identified systems, including ultracool dwarf companions. These findings enhance our understanding of stellar rotation and evolution, offering new insights into the development of secondary co-moving objects like brown dwarfs.

The second chapter investigates planet-moon interactions within our solar system by examining mass ratios, …

Pulsey: Stellar Pulsation Models In Python, Andrew Ayala

Dissertations, Theses, and Capstone Projects

The era of the Kepler/K2 and TESS space-telescope missions has inundated the astrophysics community with photometric data for millions of stars with continuous observation and very high cadence. This data confirms that nearly every observed stellar source exhibits an oscillating luminosity, with stellar pulsation being the driving mechanism behind a large fraction of the cause. The result has been an explosion in the field of asteroseismology, where the recorded luminosity variations, or "light curves", of pulsating stars to probe their interior structures. By modeling observed light curves, we can constrain values of the physical stellar parameters producing them. The brightness …

Prospects For Time-Domain And Multi-Messenger Science With Axis, Riccardo Arcodia, Franz E. Bauer, S. Bradley Cenko, Kristen C. Dage, Daryl Haggard, Wynn C.G. Ho, Erin Kara, Michael Koss, Tingting Liu, Labani Mallick, Michela Negro, Pragati Pradhan, J. Quirola-Vásquez, Mark T. Reynolds, Claudio Ricci, Richard E. Rothschild, Navin Sridhar, Eleonora Troja, Yuhan Yao

Publications

The Advanced X-ray Imaging Satellite (AXIS) promises revolutionary science in the X-ray and multi-messenger time domain. AXIS will leverage excellent spatial resolution (< 1.5 arcsec), sensitivity (80× that of Swift), and a large collecting area (5–10× that of Chandra) across a 24-arcmin diameter field of view at soft X-ray energies (0.3–10.0 keV) to discover and characterize a wide range of X-ray transients from supernova-shock breakouts to tidal disruption events to highly variable supermassive black holes. The observatory’s ability to localize and monitor faint X-ray sources opens up new opportunities to hunt for counterparts to distant binary neutron star mergers, fast radio bursts, and exotic phenomena like fast X-ray transients. AXIS will offer a response time of < 2 h to community alerts, enabling studies of gravitational wave sources, high-energy neutrino emitters, X-ray binaries, magnetars, and other targets of opportunity. This white paper highlights some of the discovery science that will be driven by AXIS in this burgeoning field of time domain and multi-messenger astrophysics. This White Paper is part of a series commissioned for the AXIS Probe Concept Mission; additional AXIS White Papers can be found at the AXIS website.

Identifying The O’Connell Effect In Eclipsing Binary Stars, Nicholas Paolella

Computer Science and Information Technology Faculty

Data science techniques have wide-ranging applications throughout scientific explorations. One, is filtering astronomical data to better understand specific populations, such as binary stars. Specifically, binary stars that exhibit the O’Connell effect are worthy of study as this phenomenon is still not well understood. The O’Connell effect can be defined as the asymmetry of maxima in the light curves, as captured by the instrument, while observing the eclipsing binary system in question. There is significant data captured by NASA and curated by Villanova University, which enabled the investigation of eclipsing binary stars and the attributes of which may help identify the …

Rising Tides: An Analytic Modeling Code Of Tidal Effects In Binary Neutron Star Mergers, Alexander O'Dell, Maria Babiuc-Hamilton

Physics Faculty Research

Gravitational waves produced by binary neutron star mergers offer a unique window into matter behavior under extreme conditions. In this context, we analytically model the effect of matter on gravitational waves from binary neutron star mergers. We start with a binary black hole system, leveraging the post-Newtonian formalism for the inspiral and the Backwards-one-Body model for the merger. We combine the two methods to generate a baseline waveform and we validate our results against numerical relativity simulations. Next, we integrate tidal effects in phase and amplitude to account for matter and spacetime interaction using the NRTidal model and test its …

An In-Depth Analysis Of The Variable Cyclotron Lines In Gx 301−2, Nicolas Zalot, Ekaterina Sokolova-Lapa, Jakob Stierhof, Ralf Ballhausen, Aafia Zainab, Katja Pottschmidt, Felix Fürst, Philipp Thalhammer, Nazma Islam, Camille M. Diez, Peter Kretschmar, Katrin Berger, Richard Rothschild, Christian Malacaria, Pragati Pradhan, Jörn Wilms

Publications

Context. The high-mass X-ray binary system GX 301−2 is a persistent source with a well-known variable cyclotron line centered at 35 keV. Recently, a second cyclotron line at 50 keV has been reported with a presumably different behavior than the 35 keV line. Aims. We investigate the presence of the newly discovered cyclotron line in the phase-averaged and phase-resolved spectra at higher luminosities than before. We further aim to determine the pulse-phase variability of both lines.

Methods. We analyze a NuSTAR observation of GX 301−2 covering the pre-periastron flare, where the source luminosity reached its peak of ∼4×1037 …