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Abstract VV 191 is a nearby (z∼ 0.05), overlapping (occulting) galaxy pair, where a multiple-armed spiral galaxy is backlit by an elliptical galaxy. The overlap is used to derive and map dust attenuation in two James Webb Space Telescope NIRCam filters (F090W and F150W) and one visible-band Hubble Space Telescope Wide Field Camera 3 filter (F606W). We present maps of the attenuation in each filter, the ratio of total to selective attenuation with a near-infrared (NIR) color excess, $R_{\widetilde{VI}}$, and the NIR attenuation curve power-law index,α, approximated via Monte Carlo resampling methods. The maps trace the optically thin outer disk of foreground galaxy VV 191b at ∼100 pc physical resolution. We find the distributions of attenuation and $R_{\widetilde{VI}}$to be close to log-normal, and the distribution ofαto be close to Gaussian throughout the disk and in high signal-to-noise ratio areas of VV191b. We analyze three spatially resolved handpicked regions in the far outer disk that are well backlit by the background galaxy. 

Stellar pulsation features provide valuable insights into the internal structure and evolutionary states of stars. In this study, we model stellar pulsations for first-overtone RR Lyrae variables, to constrain the effects that helium abundance variations have on the emitted light curves and the radial velocity curves. We model our variables using the hydrodynamic code, Radial Stellar Pulsations (RSP) from the Modules for Experiments in Stellar Astrophysics (MESA). Our results will compare light curves taken in the V-band and from TESS data to determine if the variations in light curve shapes can be accounted for by variations in the helium abundance. In particular, we will look at the brightness and pulsation phase for the compression humps observed during pulsation cycles. The compression hump is a bump in luminosity seen in some RR Lyrae variable stars, which is caused by interactions between moving stellar layers. It may be sensitive to changes in stellar composition, including the helium abundance, because the overall amount of material in the layers of a star may influence the timing and extent of interactions. By systematically adjusting the helium abundance in the models and comparing the results to real stellar luminosity data, we aim to explore how these variations influence the magnitude and timing of the compression humps. Understanding these underlying pulsation mechanisms is crucial for improving the use of pulsating stars as standard candles in cosmological measurements. 

IRAS 12397+3333 is a narrow line Seyfert 1 galaxy (NLS1) discovered as a bright soft X-ray Active Galactic Nucleus (AGN) during the ROSAT All-Sky survey. Although it exhibits a soft X-ray spectrum it shows a high degree of optical polarization. These findings make IRAS 1239+333 interesting because the high polarization is an indication of significant attenuation of the line of sight. However, the soft X-ray spectrum suggests no or only minimal intrinsic absorption. This may reveal more insight into the classification of Seyfert galaxies. In order to investigate this further, IRAS 1239 has been monitored by Swift multiple times since 2005 and has been observed by XMM-Newton in 2005 and 2019. In my poster I will present preliminary analysis of this data and discuss possible interpretations. 

Neutral hydrogen, HI, is the largest component of the interstellar medium, and is known to provide strong measures of galaxy kinematics. LADUMA (Looking At the Distant Universe with the MeerKAT Array) is a new HI survey that promises to push our direct detections of HI content to higher redshifts than ever before (z~1.3). By combining the initial LADUMA L-band data with the publicly available Galaxy Zoo/DESI catalogs we aim to explore the relationships between HI content and various measures of galaxy morphology. Here we present our research plan as well as initial results. 

Interstellar dust present in the interstellar medium creates a challenge when investigating galactic properties due to the reddening and scattering - i.e., attenuation - of light. Attenuation laws have been found to be a critical uncertainty in all astronomy, as it has been shown to vary across different sightlines, leading to different attenuation curves throughout the literature. This is especially true for low mass disk galaxies, where dust attenuation and its role in constraining galaxy spectral energy distributions (SEDs) remain poorly understood. Spatially resolved dust attenuation in these dwarf galaxies will be investigated using the technique of overlapping - occulting - galaxy pairs: the practice of calculating dust using the light lost in the galaxy pair overlap when a foreground galaxy overlaps a more distant background galaxy. In an occulting galaxy pair, the latter backlights the dusty structures in the nearer foreground galaxy. Hubble Space Telescope (HST) broadband imaging from the optical to infrared of multiple nearby dwarf (z < 0.09; M* < 1010 M⊙) occulters. With the high resolution of HST, highly accurate dust extinction maps will be constructed pixel-by-pixel among the scale of molecular clouds in the overlap region of the foreground galaxy with hundreds of independent lines-of-sight. Mapped dust attenuation in dwarf galaxies will provide vital information that is needed to investigate their properties such as SEDs, star formation, and their dust physics of the ISM. 

Telescopes such as the Rubin Observatory and Euclid Space telescopes find more and more low mass galaxies as time passes by. However, the link between small dwarf galaxy light and star mass is currently unclear. We recently found out that there are clear differences between stellar mass depending on star formation history (SFH), according to an article published by Mithi A. C. de los Reyes. This is shown in artificial data and we can show this using real observed data. Therefore, using the Galaxy And Mass Assembly (GAMA) survey, we will compare mass estimates for small dwarf galaxies with the utilization of four different methods. We seek to find out if these methods agree. Or do they not agree? What happens when a galaxy is so small it only has a few million suns of stars inside? Are there stars missing? Using jupyter notebooks and python, we can compare the GAMA data and make plots and comparisons to answer these questions. 

Dark matter plays a crucial role in shaping the structure and development of galaxies. Understanding how dark matter interacts with visible matter provides key insights into the fundamental processes that drive galaxy formation and evolution. The Illustris TNG-50 simulation provides detailed modeling of the formation and evolution of galaxies from shortly after the Big Bang and accounts for a wide range of physical processes that influence this formation. This offers the opportunity to investigate how galaxies and their structures evolve over time and the role of dark matter in this process. Using a two-point correlation study of baryonic matter in Milky Way-like galaxies in TNG-50, we seek to understand if two-point correlation signals change over time. More specifically, we aim to determine whether specific length scales of dark matter structures leave detectable imprints on a galaxy's stellar distribution. Additionally, we will investigate whether galaxies in TNG-50 exhibit asymmetric structures in stars and/or dark matter, and examine how these asymmetries evolve before and after major merger events. This is achieved by developing code to identify the symmetry axes of disk galaxies in TNG-50, aiming to explore whether the principal axes of dark matter and stellar distributions align or if any misalignment changes over cosmic time.