Yumi Choi (NOIRLab)
Refining Recent Star Formation Histrories in Low-Metallicity Dwarfs with Panchromatic HST Imaging

I will present results from the Local Ultraviolet to Infrared Treasury (LUVIT), a panchromatic HST program targeting resolved stellar populations in 22 nearby star-forming dwarf galaxies. Combining new UV through NIR imaging with archival data, LUVIT provides deep multi-band stellar catalogs across a wide wavelength baseline. I will highlight recent results from detailed CMD-based star formation history (SFH) modeling in ten of these galaxies. By jointly modeling UV and optical CMDs, we significantly reduce uncertainties in recent SFH measurements—especially over the past 1 Gyr—relative to classical optical-only approaches. I will also discuss the challenges posed by blue core helium-burning (BHeB) stars in low-metallicity regimes, and show how the inclusion of UV data improves BHeB-MS separation, mitigates model deficiencies, and enhances the reliability of recent SFR estimates compared to traditional Hα and FUV tracers.

Himansh Rathore (UA/Steward)
The LMC’s Bar - A New Probe of Disequilibrium Dynamics, Dark Matter and Galaxy Interactions

A recent collision between the Milky Way’s most massive satellites, the LMC and SMC, has left both systems morphologically perturbed and in a state of disequilibrium. This event makes these galaxies novel laboratories to study galactic dynamics and dark matter. We utilize precision astrometric observations of Gaia DR3 combined with detailed hydrodynamic simulations to explore the morphological and kinematic evolution of the LMC’s bar after a recent (~100-200 Myr ago), direct (impact parameter ~ 2 kpc) collision with the SMC. Using a new method to extract accurate star counts from crowded fields, we utilize Gaia data to place constraints on the LMC’s bar properties and compare them to the population of barred galaxies in the local universe. We demonstrate that the perturbed nature of the LMC’s bar (off-center from the outer disk, tilt out of the disk plane) is not only explainable by the recent LMC-SMC collision, but the bar tilt is in fact a direct probe of the SMC’s dark matter distribution. We utilize a semi-analytical framework to model the torques applied by the SMC on the LMC’s bar to place the first constraints on the SMC’s dark matter distribution prior to the collision. This study has broader implications to our understanding of galaxy evolution, establishing the Clouds as dynamic laboratories for bar dynamics and stellar/gaseous disk stability during galaxy interactions.