Stars, Interstellar Medium and the Galaxy Commons^™

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 …