Magnetic fields (MFs) and cosmic rays (CRs) are decidely important aspects of galactic disk and halo evolution, however, their precise roles are not yet completely understood. While there are many simulations studying galactic evolution, few have deeply explored the exact impact of CRs and MFs in the evolutionary process. The current goal of our research is to learn more about how CRs and MFs contribute to the evolutionary process by looking at how MFs grow and change in the circumgalactic medium (CGM) under the influences of CRs. Using a suite of simulated, isolated disk galaxies, we investigated the role of CRs in MF growth and galaxy evolution by comparing different galactic models, each possessing slightly varied CR physics. We present the role of CR transport on the geometry, strength, and growth rate of MFs in these simulated galactic halos.

I conducted analysis of data from 11 high-precision elemental abundance analyses of twin-star binary systems from previously published studies and included our own data for one additional pair. The goal of my analysis was to see if there were any new trends related to the differential abundances (Δ[X/H]) versus other common parameters in addition to condensation temperature. I did not find significant trends for surface gravity or effective temperature, but there is a weak correlation between the differential abundances and separation between the binary stars. As the separation between the stars increases, the absolute value of the difference in abundance increases for all chemical species. This suggests that less abundant chemical species tend to show higher star-to-star differences in abundance. This weak correlation could suggest inhomogeneity in the molecular clouds from which the binary star systems had formed.

We present optical and infrared photometry of the T Tauri binary KH 15D acquired in the 2017/2018 observing season. The data were obtained from the A Novel Dual Imaging CAMera (ANDICAM) instrument on the 1.3m telescope operated by the Small Moderate Aperture Research Telescope System (SMARTS) at the Cerro-Tololo Inter-American Observatory (CTIO). KH 15D includes two young stars (A and B, with 0.72 and 0.74 solar masses, respectively) orbiting their common center of mass, surrounded by an inclined precessing circumbinary disk. The recent data reveals Star B gradually emerging from the trailing “fuzzy” edge of the disk and is now in a stage that is completely unocculted for the first time since the system’s discovery in 1995. We use time-series photometry, or light curves, to probe the composition of the disk, derive parameters of Star B, and demonstrate the overall mechanics of the system. Recent data also shows reddening during the egress of the last eclipse, proving that the trailing edge of the disk is transparent and consists of dust-sized particles. Additionally, the most recent data displays Star B at a brighter magnitude than ever than before, allowing us to calculate an apparent I magnitude of 14.079, which is 12% brighter than previously computed.

The Lyman-alpha power spectrum has previously been used to constrain the Universe’s initial conditions and particle constituents (such as the amount and mass of the dark matter) and the temperature of intergalactic gas (which constrains reionization processes). To further improve these constraints, we use another Lyman series transition (Lyman-beta). The Lyman-beta absorption cross-section is lower than that of Lyman-alpha so it probes the intergalactic medium at higher densities where Lyman-alpha features are saturated. Therefore, the Lyman-beta forest allows for a better measurement of the slope of the temperature-density relation, allowing additional constraints on reionization and the subsequent thermal evolution. In this work, we present an analysis of the Lyman-beta power spectrum using the VLT/XSHOOTER XQ-100 Legacy Survey.

Companion-affected mass loss complicates our understanding of evolved stars; for example, theoretical models predict up to 70% of all main-sequence O stars interact with companions at some point during their lifetimes, but the details of mass loss and transfer in binary systems are poorly understood. V367 Cyg is an eclipsing, low-mass binary system with a complex geometry that offers a unique opportunity to better understand mass transfer processes; the primary star has overflowed its Roche lobe, resulting in an accretion disk that surrounds the secondary star. Using new spectropolarimetric data of V367 Cyg taken with the University of Wisconsin’s Half-Wave Polarimeter (HPOL) at the Pine Bluff Observatory, I have resolved the behavior of the accretion disk by determining the position angle and intensity of the polarized light from the system as a function of orbital phase. Here, I will present an analysis of this data and discuss their implications for the mass-loss geometry of the system. By constraining the properties of this interacting binary, we can more precisely study the details of stellar mass transfer.

Galaxy clusters are collections of galaxies that form the largest gravitationally bound structures in the universe. Because these galaxies are clustered together, they undergo a wide variety of processes and operate under a multitude of mechanics, differing from non-clustered galaxies, like our own Milky Way. One such example is ram pressure stripping. A galaxy that falls through the hot and dense Intracluster Medium (the space between clustered galaxies) is subject to a "wind" force that can strip it of its gas, usually producing a long gaseous tail emanating from the galaxies causing it to be dubbed a Jellyfish Galaxy. This phenomenon can be incredibly impactful as it can "quench" star formation in the galaxy or, in other words, it can cause the galaxy to “die.” A galaxy is considered quenched when it has insufficient gas to form stars, and it is still not well understood why some galaxies become quenched and others do not. Learning more about this process can inform us on the life cycle of both the galaxies themselves and the cluster as a whole. We used the RomulusC simulation data, run on the NSF Blue Waters Supercomputer, which simulated a large galaxy cluster in high resolution. This simulation has allowed astronomers to study ram pressure stripping in a realistic setting for the first time. Comparing the results of this simulation to observations will supplement our understanding of galaxy clusters and the movement of matter in these colossal and highly dynamic systems.

Red supergiants (RSGs) are evolved massive stars that represent extremes, in both their physical sizes and their cool temperatures, of the massive star population. Effective temperature T_eff is the most critical physical property needed to place a RSG on the Hertzsprung-Russell Diagram, due to the stars' cool temperatures and resulting large bolometric corrections. Several recent papers have examined the potential utility of atomic line equivalent widths in cool supergiant spectra for determining T_eff and other physical properties and found strong correlations between Ti I and Fe I spectral features and T_eff in earlier-type cool supergiants (G and early K) but poor correlations in M-type stars, a spectral subtype that makes up a significant fraction of RSGs. We have extended this work by measuring the equivalent widths of Ti, Fe, and Ca lines in late K- and M-type RSGs in the Milky Way, Large Magellanic Cloud, and Small Magellanic Cloud, and compared these results to the predictions of the MARCS stellar atmosphere models. Our analyses show a poor correlation between T_eff and the Fe I and Ti I lines in our observations (at odds with strong correlations predicted by stellar atmosphere models), but do find statistically significant correlations between T_eff and the Ca II triplet (CaT) features of Milky Way RSGs, suggesting that this could be a potential diagnostic tool for determining T_eff in M type supergiants. We also examine correlations between these spectral features and other physical properties of RSGs (including metallicity, surface gravity, and bolometric magnitude), and consider the underlying physics driving the evolution of atomic line spectra in RSGs.

In the near future, spectrometers on extremely-large ground-based telescopes will conduct some of the first searches for life beyond the solar system. These telescopes will use high-spectral resolution observations of reflected light from nearby exoplanets to search for abundant oxygen in the exoplanet’s atmosphere. While photosynthesizers produce abundant O₂ on our planet, a planet that has lost its ocean may also have high atmospheric O₂ – even up to many times the Earth’s current abundance. This is because as the ocean evaporates, water vapor high in the atmosphere can be broken up by UV light from the star, allowing the hydrogen to escape to space and leaving the oxygen behind. Here we use a radiative transfer model (SMART) to generate high-resolution synthetic spectra of both Earth-like and ocean loss worlds to determine which spectral features can help distinguish the source of abundant oxygen in an exoplanet’s atmosphere. We compare atmospheric models of Proxima Centauri b, a planet orbiting a nearby star, to quantify the strength of absorption bands of different molecules. Based on these models, we found that the extremely high oxygen atmospheres resulting from ocean loss have strong suppression of oxygen bands due to additional broad absorption caused by the collisions of O₂ molecules, which is not present for the smaller amounts of oxygen generated by photosynthesis. We find that the presence of a strong oxygen band centered at 0.69 micrometers (µm) combined with the suppression of the oxygen band at 1.27 µm would indicate an ocean loss scenario and not a photosynthetic biosphere. These results emphasize the need for accurate models, and ground-based high-resolution spectrometers that are sensitive to wavelengths shorter than 0.7µm to detect diagnostic O₂ collisionally-induced absorption.

X-ray binaries consist of a star gravitationally bound to a compact object (white dwarf, neutron star, or stellar mass black hole). Matter from the star is pulled onto the compact object and accretes in a disk which emits high-energy X-rays. These objects have variability observable on human time-scales—days and weeks rather than millions of years—and provide insight into high-energy physics. In this project we analyzed the light curves of time-variable objects to identify candidate binary systems. We cross matched data from optical variability surveys such as ASAS-SN, ATLAS and ZTF with the ROSAT all-sky X-ray survey. We were able to confirm known cataclysmic variables (CVs) and active galactic nuclei, and also discovered new CVs. These methods will be useful in identifying these rare objects in LSST’s massive data set in a few years.

Neutron stars are extremely dense objects that are the remnant of exploded massive stars. The purpose of this project is to try to discover new neutron stars in orbit with normal stars. These new systems will improve our understanding of the processes of stellar evolution. To conduct the research, I cross-matched data from two different instruments, ROSAT and ZTF. ROSAT provides a comprehensive survey of the X-ray sky, while ZTF provides a real time stream of time varying optical sources. The combination of the two can identify neutron star binaries as they change in brightness. I continue to sift through the data on weekly basis to enhance the chance of finding new binary outbursts. By the end of this project, I expect to construct certain data filters that will result in the most outbursts. I expect to find a few objects that could potentially be what we are searching for.

The Zwicky Transient Factory (ZTF) is a telescope located at Caltech in southern California. It is part of a new generation of wide field survey telescope programs. With its 47 square degree field of view and the ability to cover 4200 square degrees per hour of the night sky, ZTF is equipt to complete its survey of the Northern hemisphere. ZTF takes photometric data in multiple color bands including visual (r and g) and (i) bands increasing the accuracy of data collected on an observed body. It’s limiting magnitude is ~21 allowing us to see deeper into our universe. We constructed a pipeline of code which pulls photometric data from ZTF and fits light curves for asteroids with previously reported orbital parameters. A light curve is a recorded fluctuation in light intensity of a variable body. As an asteroid rotates its albedo or surface reflectivity varies producing the variation in flux we measure as a light curve. From a light curve you can calculate many properties of the body such as period, diameter, and mass. Our pipeline fits the observed light curve for its period and, for a subset of the asteroids with previously known periods reported in the Light Curve Database (LCDB), we test the accuracy of the fitting process. Of the initial ~4000 asteroid samples, 437 had periods reported in LCDB. In this subset we matched ~60% of the reported rotation periods within 5%. We continue improvements on the pipeline, specifically in outlier rejection, in hopes to use our pipeline in future telescopes like the Large Synoptic Survey Telescope. As well as data collection hoping to fully resolve the Jovian Trojans, two asteroid groups that co-orbit with Jupiter.

The Time-Domain Spectroscopic Survey (TDSS) is the largest spectroscopic survey ever carried out specifically targeting variable objects. In this poster we consider the subsample of some 22,000 TDSS variables characterized spectroscopically as stars, and evaluate best methods for retrieval and analysis of light curve data from the Palomar and Catalina surveys. We analyze light curves using Python and the VARTOOLS code of Hartman & Bakos (2016). A combination of the VARTOOLS output, spectroscopic information from Sloan, and classification of periodic variables in Catalina from Drake et al. (2014) is used to guide future classification of the entire TDSS sample, including some discussion of the larger variable sample for which no significant periodicity is found. The particular patterns of each type of variable star we find can be used to learn more about stellar evolution and the physical processes taking place within stars. The discovery of new and unexplained types of variable stars can also act as a driver that leads astronomers to an explanation of the underlying mechanism behind it. The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. AST-1659473, and by the Smithsonian Institution.

We identified an optically varying light source in the night sky labeled PTFS1623al. In our search for interesting stars, this object caught our attention when we found that it was within the X-ray emitting region 1RXS J235728.5+671600. The light that came from the object varied by 2.5 magnitudes over a 96 minute period. An average light source only varies by a tenth of a magnitude over a week, month, or even a year time scale. The large change in magnitude over such a short period sparked our investigation. We confirmed this 2.5 magnitude variability with the Neil Gehrels Swift space based gamma ray observatory using the X-Ray Telescope as well as confirm a correlation between the optically varying source and the X-ray emitting source. Using the Keck telescope on Mauna Kea and the Low Resolution Imaging Spectrometer or LRIS we collected spectroscopic data. Spectroscopic data is a different way of viewing light where the individual molecules in the object radiate light at different wavelength allowing us to identify the specific elements in an object. Geometry of the object can also be identified by the shape of the spectral lines. We identified strong double-peaked Hydrogen and Helium emission lines with phase-dependent morphology. After reading through scientific literature and making comparisons, we concluded that the features present in the spectroscopic data are consistent with a magnetic cataclysmic variable, or a magnetic accreting white dwarf star. Accretion is the process of moving mass from one star to another, so this system is a binary system with an unknown donating star. A white dwarf and cataclysmic variable are two exotic classifications of a star with unique spectral characteristics. We present our observations and discuss their implications for our understanding of the system parameters.

We have built an air quality sensor to track smoke from wildfires at UW’s Manastash Ridge Observatory (MRO). The increasing number of wildfires over the last few years has raised concern that smoke may contaminate the telescope optics at MRO. Our goal is to measure the amount of smoke in the air at the site in real time. Our design consists of an Adafruit micro-controller connected to two dust sensors that connect to Wi-fi. We interviewed Edmund Seto, a professor at UW, since he has much more experience with building sensors. He suggested that we use multiple of the same device so that we could average the data or have a backup sensor if one were to stop working. Using Arduino code and Adafruit.io, we were able to code the micro-controller and connect the data to a Wifi-interface so we could watch the data come in. We are currently field testing the sensor in Seattle, but we expect to permanently install at the MRO this summer.

The James Webb Space Telescope (JWST) has the power to resolve many unanswered questions in the field of astronomy. The new telescope, which has taken many years and large amounts of resources to build, will have a limited lifetime so it is imperative that it is used as efficiently as possible. The unprecedented power of the JWST means that for the first time it may be possible to detect the clustering of high-redshift galaxies, and this could help to clarify uncertain details about the early universe. The purpose of this project is to determine the ability with which the JWST will be able to detect the clustering of early galaxies and the most efficient survey strategies for realizing this capability. Using simulation data, we are able to take into account JWST detectability limits and analyze clustering at different redshifts (z=6, z=8, and z=10). By comparing the simulation galaxies to a random test case, we have come to the conclusion that the clustering of high-redshift galaxies will likely be detectable with the JWST. Simulating different survey strategies then allows us to determine how to maximize the JWST's efficiency. The amount of time that the JWST spends pointed in a specific direction determines the depth of the survey. For a given amount of time, a deeper survey will be able to pick up on dimmer galaxies, but it will cover a smaller area. Our next step is to determine an ideal combination of depth and of area for the detection of early galaxy clustering at different redshifts in order to best plan for the JWST's launch.

We present a study on 13 years of HPOL optical linear spectropolarimetry of the famous star P Cygni. P Cygni is a Luminous Blue Variable, an important transitional phase in the lives of the universe's most massive stars. We revisit previous findings on the nature and variability of P Cygni's observed linear polarization and report on discrete features in P Cygni's observed polarization spectrum. Using this dataset we also test the assumption that line blanketing effects suppress all intrinsic polarization from strong emission lines. This assumption is vital in determining the wavelength dependence of P Cygni's intrinsic polarization. Our results allow us to constrain the geometry of the polarizing region to better understand the circumstellar material around P Cygni.