Strong gravitational lensing combined with JWST resolution enables studies of star formation on ~10-100 pc scales at Cosmic Noon. As part of the JWST LEGGOS survey, we present an updated strong lens model of the galaxy cluster SDSS J1110+6459 (z = 0.659), which lenses the clumpy star-forming galaxy SGAS J1110 at z = 2.481 into a highly magnified ~17″ giant arc. Using JWST NIRCam imaging, NIRSpec spectroscopy, and archival HST data, we confirm and refine four multiply imaged background sources and map >20 star-forming clumps across each image of the primary arc. The model yields a total magnification of ~24 for the giant arc, with clump magnifications spanning ~4-19. Fractional magnification uncertainties across the arc range between 3-9%, with a ~2-8x improvement in clump magnification precision over previous work. This precision is enabled by the high density of JWST-resolved clump constraints, which tightly probe the underlying mass distribution. These results provide a foundation for resolving star-forming structure and studying galaxy growth at Cosmic Noon.

Faint stellar systems probe the low-mass end of galaxy formation and the boundary between star clusters and dwarf galaxies. We present the discovery and analysis of GHOSTS II, an unusual stellar system identified in archival HST imaging from the GHOSTS survey toward Messier 83 (M83). Although projected near M83, its stellar population indicates a distance of ~7.6 Mpc, showing that it is a background system and not physically associated with the galaxy. Using masked imaging and aperture photometry, we measure its structural and integrated properties. The system has a compact half-light radius of 31-33 pc, an absolute magnitude of M ~ -7, a color of ~0.46 mag, and appears isolated with no nearby host galaxy within ~1 Mpc. These properties place it in an unusual regime: compact and low-luminosity like an extended cluster, yet isolated and exhibiting a color suggestive of a younger, possibly star-forming population. GHOSTS II does not match known classes of stellar systems, and its properties provide insight into formation pathways, structural evolution, and dark matter at the lowest mass scales.

We analyze 1146 halos ( analogous to galaxy clusters) and over 14 million subhalos (analogous to galaxies) in the TNG300 cosmological simulation to test for velocity-luminosity segregation, indicating that brighter subhalos are kinematically cooler. Using a likelihood method, we measure the satellite sub halo velocity-dispersion-halo mass function (<rsat,lD - M2ooc) as a function of subhalo stellar mass threshold (Msat)- We first find the result of performing the likelihood analysis on subhalos within three-dimensional spheres with radius R 2ooc centered on the halos' Brightest Central Subhalos (hereafter referred to as BCGs). Then, we collect all subhalos in projected cylinders of radius R2ooc centered on the BCGs. We employ a velocity cut before performing likelihood analysis on the surviving subhalos. We compare the magnitude of the VLS in projected halos to that of the spherical halos, and find there is no statistically significant difference between the two. Notably, there is a substantial drop in the relation's normalization, particularly for subhalos with Msat > 1010 M0 . The slope of the relation remains fairly constant, while the scatter increases marginally with Msat·

Widespread star formation has been found in the halo of M82, a nearby edge-on spiral galaxy featuring a prominent nuclear starburst and strong gas and dust outflow. However, whether this phenomenon is characteristic of galaxies containing starbursts is still unclear. We investigate another nearby edge-on starburst galaxy, NGC 4631, which shares many similar physical characteristics to M82, to see if widespread star formation is a feature of a starburst galaxy halo other than M82. To do this, we take Hubble ACS photometry data of ten fields from GHOSTS covering the disk and halo of NGC 4631. We use an intensity contour over a DSS2-Red FITS image to define a mask for the NGC 4631 disk and nearby satellite galaxy. We use isochrones from PARSEC to define a region of the CMD corresponding to ’young’ (≤ 100 and ≤ 400 Myr) stars. We map these stars in RA-Dec space to determine how they are oriented throughout the thick disk and halo. We find significant numbers of young stars out to multiple kpc from the galactic plane. This provides strong evidence for widespread halo star formation in NGC 4631, which in turn suggests that such halo star formation may be a feature of starburst galaxies, and not a phenomenon unique to M82.

A new method for recovering the properties of bars has been developed and tested using edge-on-oriented N-body representations of barred disk galaxies. This process involves inferring a 3-dimensional mass distribution from a 2-dimensional surface brightness image. The recovered 3D mass distribution is then used to obtain the gravitational potential of the barred system. We use this gravitational potential to construct orbits of 30,000 stars within the system. Each orbit is superposed with different weights to best-fit the 2D surface brightness image and 2D Integral Field Spectroscopic data. We have validated this method for near-face-on oriented barred disk galaxies by constructing mock data from an N-body simulation of a barred disk galaxy with a moderately weak bar. We were able to correctly recover the bar pattern speed and supermassive black hole mass from the mock data using this method. Following this success, we apply this method to the barred spiral galaxy, NGC 4371, using data from both SINFONI and MUSE spectrographs.

We measure transverse proper motion velocities of LMC Wolf-Rayet (WR) stars using Gaia DR3 astrometry. The combined velocity distribution of WNh, O If*/WN, and WNL very massive stars (>100 M⊙; VMS) shows both slow, unejected objects (v⊥<10 km s−1) and stars dominated by fast, runaway velocities (v⊥>24 km s−1). This supports expectations that VMS ages are comparable to the dynamical ejection timescale (∼1.5 Myr). These kinematics share similarities with those of lower-luminosity, classical WNh, O If*/WN, and WNL stars, as well as the SMC field OB stars, suggesting that dynamical ejections may also dominate these populations. In contrast, both single and binary WNE stars are ejected populations that show single-peaked velocity distributions, suggesting a different ejection mechanism(s). We speculate that single WNE stars might result from explosive mergers onto the shell-burning layer, thereby stripping the H envelope. Binary WC stars appear to be faster (median v⊥=54 km s−1) and have higher luminosities than singles (median v⊥=38 km s−1), suggesting that single WC stars are not descendants of the binaries. Thus, the binaries are probably stripped by mass transfer, while the WC singles likely originate from another process. The high velocities of binary WC stars are consistent with some predictions that lower mass clusters generate fast dynamical ejections. Single WC and WN3/O3 stars have ambiguous kinematics, but both show high v⊥ (median ∼38 km s−1), possibly linked to their lower masses.

In order to properly characterize the planets a star may be hosting, first the parameters of the host star must be well-determined. π03 Orionis is a nearby star that is on NASA’s provisional list of 164 target stars for the Habitable Worlds Observatory (HWO) exo-Earth survey. We analyzed new long-baseline optical interferometric data from the CHARA Array with the MIRC-X beam combiner which, when combined with precise distances, spectroscopy and photometry, leads to improved constraints on the stellar parameters of π03 Orionis. Most notably, we were able to constrain the limb-darkened angular diameter to 1.490 mas ± 0.008. From this value, we calculated other fundamental stellar parameters.

Luminous Blue Variables (LBVs) are massive stars with evolutionary origins that remain poorly understood. Following the classification by Agliozzo et al. (2021) and kinematic analysis by Deman & Oey (2024) using Gaia proper-motion data shows that these stars exhibit distinct kinematic behaviors. Class 1 LBVs (with dusty nebulae) display accelerated velocities , and Class 2 LBVs (without nebulae) show no clear evidence of similar motions. One possible explanation is that the Class 1  velocities arise from binary evolution, in which the supernova explosion of a former companion imparts a velocity kick.  If this scenario is correct, such events may leave observable signatures in the surrounding interstellar medium, and the dusty nebulae around Class 1 LBVs may support this scenario. Identifying actual supernova remnants (SNRs) would be definitive confirmation. To evaluate this scenario, we investigate the environments of eighteen LBVs in the Large Magellanic Cloud (LMC) using the SIMBAD database and MCELS2 imaging survey. By identifying catalogued objects within a 3 arcminute radius and incorporating published proper motion data, we search for potential (SNRs) associated with our target LBVs. By comparing Class 1 and Class 2 populations, this study aims to test whether signatures of past supernova interactions are associated with high-velocity (Class 1) population and absent in the lower-velocity (Class 2) population.

Abstract not available

The James Webb Space Telescope (JWST) and its powerful infrared observing capabilities have opened the door for observation and analysis of the universe at cosmic dawn, with one aspect being the formation of large structures. The focus of our study is on identifying galaxy protoclusters using NEXUS, a JWST multi-cycle spectroscopic survey. We use NIRCam and NIRSpec data from epochs 1 and 2 from both the Wide and Deep tiers, which compose a catalog of galaxies up to z~8. This protocluster identification is accomplished using an adaptive linking-length Friends-of-Friends (FoF) algorithm to search for protoclusters with n > 4 members at redshift z > 4 with line-of-sight velocity dispersion of less than 5000km/s. This will help build the existing database of known protoclusters by adding analysis on new data and allow for more studies of protoclusters in the future. Out of the 20 most overdense protoccluster candidates, we found 3 containing galaxies with spectroscopic data. One of these protoclusters contains an additional galaxy with a spectral line observed in NIRCam data. We will continue analysis of this cluster to determine the redshift of member galaxies more accurately and refine a list of cluster members.

We present a surface brightness profile analysis of the nearby dwarf galaxy NGC 5102 to constrain the masses of its nuclear star cluster (NSC), bulge, and disk components. Accurate mass measurements in low-mass galaxies are essential for understanding supermassive black hole (SMBH) seeding mechanisms, as different formation scenarios predict widely varying black hole mass distributions and occupation fractions. Previous studies have demonstrated that indirect scaling relations can yield inconsistent SMBH mass estimates, particularly in low-mass systems, highlighting the need for robust, observation-based approaches. 

Using HST imaging combined with complementary ground-based data, we construct an azimuthally averaged surface brightness profile and decompose it into four components: an NSC, two bulge-like structures, and a disk. From the best-fit models, we derive total luminosities for each structural component and convert these into mass estimates using both constant and radially varying mass-to-light (M/L) ratios. Our analysis demonstrates how detailed surface brightness modeling provides a powerful, direct constraint on galaxy structure and mass distribution, offering an important benchmark for testing scaling relations and improving our understanding of black hole growth in low-mass galaxies.

We present a multi-wavelength analysis of the protoplanetary disk around T Tauri star T28 in Chameleon I star forming region using X-shooter and Spitzer/IRS spectra in tandem with UV and mid-infrared photometric observations. We use the hydrogen column density of the region to constrain the optical extinction. We derive the stellar radius from veiling measurements and model the accretion shock to obtain the mass accretion rate. We use irradiated accretion disk models and determine that the disk is pre-transitional with a cavity filled with optically thin dust extending to 10 AU. We find a decreasing Mg-to-Fe ratio with decreasing radius, and Mg rich silicates in the outer wall and disk.

Protoplanets can be difficult to detect in accretion disks of young stars due to the disk’s high opacity and the forming planets’ small size. A potential indicator of planet formation in the disk is a depletion of refractory materials in the accretion flows. This suggests that a protoplanet is accreting this material onto itself somewhere in the disk, leading to less of that material being accreted onto the star. Our goal is to determine the calcium abundance reaching the inner disk in a sample of nine accreting young stars (Classical T Tauri stars) in the Taurus star-forming region to find candidates for planet formation. We find the calcium abundance by comparing the ratio of the luminosities of the Hα and Ca II K lines and the mass accretion rate of each star to the predictions of a grid of magnetospheric accretion models with a range of abundances relative to solar following Micolta et. al. (2024). We measure the fluxes of Ca II K and Hα in the spectra we obtained with the MIKE spectrograph in the Magellan telescopes. Mass accretion rates of the stars were taken from Ingleby et. al. (2013), from which we also took low resolution continuum spectra from 2896.31A to 5696.56A obtained from the STIS instrument on board HST in the DAO program (Herczeg 2011), and stellar parameters. To find the line fluxes, we multiplied the equivalent widths measured in the MIKE spectra by the continuum flux, corrected by reddening. We determined the continuum flux for the Ca II K line using the DAO continuum. We used accretion shock models following Calvet & Gullbring (1998), fitted to the DAO fluxes and the flux at the J band, to estimate the continuum flux at Hα. We used distances taken from Ingleby et. al. (2013) to get the luminosities. We find that three of the nine stars have significant  calcium depletion, suggesting that they may have planets forming in their disks.

Despite the ubiquity of moons and rings in our own solar system, no exomoons or exorings have been confirmed to date. However, the presence of these non-planetary bodies around exoplanets is expected, raising the question of their detectability with upcoming high-contrast imaging missions such as the Habitable Worlds Observatory. Motivated by cases in the Solar System where moons or rings outshine their host planet at wavelengths in the UV/Visible/NIR,  we investigate the detectability of exomoons analogous to Triton and exorings analogous to Saturn’s rings using reflected light imaging with the Habitable Worlds Observatory. Our analysis demonstrates that icy rings and large icy moons can be significant sources of reflected light in the UV/Visible/NIR, making these objects detectable with the Habitable Worlds Observatory across a wide range of orbital separations and distances. These findings raise the need to further develop methods to disentangle exomoon and exoring signatures from exoplanet signals in observations because these sources will be blended and spatially unresolved. 

JWST allows precise spectrophotometric monitoring of substellar objects; these observations reveal the atmospheric variability of these worlds driven by mechanisms operating across multiple pressure levels. This same precision now permits extremely sensitive searches for transiting exosatellites, small companions which may orbit these worlds. Using a novel simultaneous dual-band search method to account for host variability, we demonstrate a search for transiting exosatellites in an 8-hour JWST/MIRI LRS lightcurve of the nearby (2.0 pc) substellar binary WISE J1049-5319 AB, containing two ~30 Jupiter-mass brown dwarfs viewed near edge-on. We detect no statistically significant transits, however, our injection-recovery testing demonstrates sensitivity to satellites as small as 0.275 R⊕ (0.96 Io-radii or ∼1 lunar radius), creating transit depths of ~300ppm, and with satellite-to-host mass ratios >10^-6. This method creates a path forward for detecting objects analogous to the Jovian moon system around directly imaged brown dwarfs, free-floating planets, and wide-orbit exoplanets, dozens of which are already scheduled for JWST light curve monitoring. In our Solar System, each giant planet hosts, on average, 3.5 moons above this mass ratio, suggesting that the regime JWST now probes will be well populated with such companions. This technique, and the sensitivity it possesses, is a critical step toward detecting exosatellites and ultimately enabling constraints on the occurrence rates of small terrestrial worlds in orbit of 1-70 Jupiter-mass hosts.

Abstract not available

NGC 1275 is the brightest central galaxy in the Perseus cluster. The active galactic nucleus (AGN) within NGC 1275 is notable for its strong and variable radio activity, likely tied to the production of radio jets that inflate large bubbles in the hot intracluster medium. High spatial resolution X-ray imaging can separate the AGN from the bright ICM, but monitoring the mass accretion rate onto the black hole and establishing disk–jet connections in NGC 1275 requires high-cadence monitoring. Here, we report on X-ray monitoring of NGC 1275 using data taken over 20 years with the Neil Gehrels Swift Observatory. Subtracting the ICM in each observation allows X-ray emission from accretion onto the black hole to be traced reliably, with typical flux errors of ∼ 3%. Sharp flaring by a factor of ∼ 2 over mere days is detected starting on MJD 59956 (2023 Feb. 21). The profile of the flaring is inconsistent with simple predictions for tidal disruption events. The mass of the black hole in NGC 1275 is debated, but the flares imply an emission region consistent with r ≃ 170 (t/1 day) (MBH /108 M⊙) GM/c2. Overall, our results indicate that coordinated, moderate-resolution X-ray imaging and spectroscopy and radio monitoring could effectively trace disk–jet connections in the AGN that most vividly impacts large-scale structure, and be extended to additional cluster AGN using Swift, XMM-Newton, NuSTAR and future X-ray missions. 

We analyze a luminous ultraviolet and X-ray transient in a galaxy at z≈0.79, coincident with the galaxy nucleus. Archival XMM-Newton data reveal persistent X-ray emission, while Swift observations detect a strong ultraviolet flare (LUV∼4×1045 erg s-1) and an X-ray increase of ∼30×. The high luminosity, nuclear location, and large variability are consistent with a tidal disruption event (TDE). However, the presence of pre-flare X-ray emission suggests an active galactic nuclei (AGN), raising the possibility of a TDE occurring in an already active system or extreme AGN variability.

The Nancy Grace Roman Space Telescope’s Coronagraphic Instrument (CGI) will provide the first opportunity to directly detect mature giant exoplanets in reflected light. However, such detections are expected to be challenging, as most known radial velocity planets lie near the limit of CGI’s sensitivity. In contrast, exorings of these planets, analogous to Saturn’s ring system, are likely to be much more accessible. Our modeling shows that rings can outshine their host planets by one to two orders of magnitude or more in many cases, making them easier to detect than the planets themselves. These signals, however, complicate the interpretation of reflected-light measurements, since the contributions from the planet and rings will be blended and the presence of rings will not be known a priori. As a potential method to disentangle these signals, we model reflected-light phase curves of ringed and unringed planets. Ring systems produce a distinctive signature, with four extrema per orbital phase curve instead of the two expected for unringed planets, enabling robust confirmation of rings with multi-epoch CGI observations. As a demonstration, we simulated CGI observations of Eps Eri b (3.5 AU, 1 M_jup) with a Saturn-like ring system, showing that such a configuration would be detectable with CGI. These results suggest that the brightness of rings may expand the pool of viable CGI targets to include planets previously thought to be beyond its reach. We conclude that CGI is poised to provide the first observational constraints on the prevalence of Saturn-like rings around giant exoplanets.

In the crowded center of the Milky Way, it is difficult to pick out specific objects for spectral and energy analysis. To extract scientifically meaningful observations about astrophysical objects, we must perform Blind Source Separation (BSS). However, traditional BSS methods struggle to extract smooth separations in busy areas. In this work, we introduce DOGS (DOuble Gaussian Mixture Model with Starlets), a flexible BSS framework that exploits GMM probability fitting for multiple levels of starlet structure. The framework first splits the background from compact objects, then splits foreground objects into independent components. We use this framework to evaluate the spectral properties of distinct physical objects: the black hole Sgr A*, a pulsar wind nebula, star cluster, and the plasma environment in which they are embedded. The adaptable nature of the DOGS framework excels in analysis of more complex spectral structures, such as splitting the pulsar wind nebula from its tail. Our results show the generalizable potential of this method for astronomical observations with any energy distribution.

A luminous quasar has recently been discovered to anchor an overdense, large-scale protocluster in the early universe (z=6.6). Discovered near the end of the Epoch of Reionization, this structure offers astronomers insight into the growth of early supermassive black holes (SMBHs) and the formation of galaxies and clusters. In this study, we search for active galactic nuclei (AGN) within the protocluster to reveal their role in galaxy/cluster formation. Our study utilizes data obtained with JWST/NIRSpec through GO2028 to identify 379 galaxies in the field of view and search for signs of AGN (i.e., broad emission lines) in the protocluster. The field galaxies fall into a redshift range of 0.002 to 8.34, with 12 between 6.5 and 6.7 (the quasar redshift). 110 galaxies show H-alpha and/or H-beta emission lines, and 110 galaxies show [OIII] emission lines (12 at the quasar redshift). None of the galaxies at the quasar redshift show signs of AGN. We are currently performing more detailed analyses of the galaxies in this field in order to refine our understanding of AGN activity in protoclusters and environmentally dependent galaxy evolution.

A deeper understanding of the masses of galaxy clusters, which consist of both baryonic and dark matter, will lead to better constraints on cosmological parameters. Because cluster masses are not directly measurable, we can determine the masses of galaxy clusters by estimating their internal dark matter velocity dispersions, which are inferred from velocity dispersions of satellite galaxies within each cluster. However, because satellite galaxies are biased tracers of dark matter density and velocity fields, a velocity dispersion bias is introduced. Recent cosmological simulations indicate a ‘brighter is cooler’ effect: galaxies with larger stellar mass exhibit a slightly smaller normalization in the velocity dispersion-total mass scaling relation than galaxies with a smaller stellar mass. We confirm this expectation on a percent-level by utilizing empirical data from large surveys within an ensemble velocity likelihood (EVL) model.

The evolution of massive stars still holds many mysteries. It is known, however, that most will be in interacting binary systems at some point in their lifetimes, and classical OBe stars are no exception. These special stars are massive Hα emission-line stars thought to originate via mass transfer in a close binary pair. Furthermore, it is hypothesized by, e.g., Dorigo Jones et al (2020) that field OBe stars are accelerated by the supernova of a previous companion, based on the velocity distribution of classical OBe stars in the SMC. We aim to corroborate these findings with the velocity distribution of a sample of Be stars in the LMC. We obtain the proper motions of our sample stars from the latest Gaia catalog and discard unreliable data using photometric and astrometric uncertainties. The local peculiar velocities are then calculated by accounting for the systemic velocity within 5’ of each star. We then show that the velocity distribution of LMC Be stars is consistent with SMC OBe field distribution.

Hot Jupiters are giant gaseous exoplanets in close orbits to their host stars with high (T>1000 K) atmospheric temperatures, providing the best opportunity for observational characterization of any type of exoplanet. One technique, high-resolution emission spectroscopy, provides insights into their atmospheric dynamics and composition through detailed measures of spectral features. In particular, hot Jupiter atmospheres exhibit large day-night temperature differences, such that the emitted spectra vary depending on the region of the planet under observation. Three-dimensional models of hot Jupiter atmospheres predict complex temperature structures, but it remains challenging to determine how varying properties across the visible hemisphere contribute to the disk-integrated emission spectrum. In this project, we have adapted code to calculate regional spectra and analyze the spectral features using 3-D atmospheric models of the quintessential hot Jupiter WASP-76 b. We focus on CO and H2O lines in our analysis as they are dominant sources of opacity in hot Jupiter atmospheres, and equilibrium chemistry predicts large (for H2O) or small (for CO) changes in abundance with varying regional atmospheric temperature. We find regional differences in spectral features and use this to link the distinct chemical and thermal structures in different regions of the planet to their influence on particular spectral features. We also explore how these spectral features vary with orbital phase. Our work will impact how data from high resolution emission spectroscopy of hot Jupiters is interpreted, ultimately to understand the 3-D structure of a hot Jupiter atmosphere in more detail.

We verify the existence of four satellite dwarf galaxies of the nearby spiral galaxy NGC 2683, initially identified as candidates in the Exploration of Local VolumE Satellites (ELVES) survey and subsequently imaged with the Hubble Space Telescope (HST) as part of a follow-up SNAP program.  We perform point-spread function photometry using the DOLPHOT stellar photometry package and apply completeness cuts informed by extensive artificial star tests. Additional color–magnitude cuts are used to isolate the red giant branch (RGB) stellar populations of each satellite. Structural parameters, including half-light radius, ellipticity, and position angle, are derived via Markov Chain Monte Carlo fits of exponential and Sérsic surface density profiles to the spatial distribution of resolved RGB stars. Distances are estimated using measurements of the tip of the red giant branch (TRGB). Our results confirm the existence of all four candidate galaxies and reveal a diverse range of structural properties consistent with known dwarf satellites in the Local Volume.

Currently there is a gap in the detection of (sub) stellar companions transiting low mass stars. 

Project 1 - We aim to explore the detectability threshold of these companions in the Rosette Nebula for the Nancy Grace Roman Telescope. We used an injection-recovery pipeline on a JWST lightcurve for the Rosette Nebula and concluded that adopting a 7σ detection threshold is acceptable for transit detection in Rosette.

Project 2 - We aim to explore the detectability threshold of these companions in the Upper Scorpius (Upper Sco) cluster for the Nancy Grace Roman Telescope. We approximated astrometric precision values for various stars in Upper Sco using the Roman ETC. We plan on determining the lower limit of companion mass as a function of separation of our host-companion system. We conclude that the estimated companion mass detection limit for late M-type stars and young brown dwarfs (BDs) in Upper Sco falls in the range of ∼1 Neptune Mass to 0.3 Jupiter Mass.

Although protoplanetary disks are mostly cold, there are FU Orionis outbursts during which the disks become hotter and more luminous than their central star. Independently, there is evidence of solar system materials that must have been heated to temperatures far in excess of the environments in which they are typically found. These topics are explored in two phases: (1) A summary and analysis of FU Orionis properties as found in literature, with a critical examination of discrepant results, and (2) use of numerical simulations to study the possibility that localized high-temperature events could result from a large object plunging through the disk at radii much larger than those where FU Orionis outbursts occur.

Cold, faint stellar companions, such as brown dwarfs, provide critical insight into the processes that govern stellar and substellar formation and evolution, particularly as members of higher-order multiple systems where their occurrence remains poorly constrained. Recent high-contrast imaging observations with MagAO-X revealed E Hya, an evolved K giant previously known as a single star, with two previously unknown faint point sources near the host, suggesting the possibility of E Hya to be a hierarchical triple system. Notably, the faintest point source appeared significantly fainter at shorter wavelengths, indicating that it is very red and cool, properties consistent with a brown dwarf. We present multi-epoch astrometric measurements to assess if the companions are bound and photometric analysis across multiple filters to constrain their respective spectral types. We also developed and implemented a data reduction and calibration framework tailored to MagAO-X high-contrast imaging data for precise astrometric and photometric analysis. In combining gravitational analysis and spectral characterization, we evaluate whether E Hya represents the first confirmed evolved giant hosting both a stellar and brown dwarf companion in a hierarchical triple system, and discuss the implications for substellar formation and dynamics in higher-order systems.

New JWST observations of massive galaxy clusters have revealed populations of globular clusters (GCs) out to z~1.0. These unprecedented observations present a new opportunity to test models of globular cluster evolution at earlier epochs. In this work, we present model globular cluster populations around brightest cluster galaxies (BCGs) in IllustrisTNG-100 and 300 throughout six epochs of evolution.  We investigate how properties of the globular cluster population evolve over time and search for observable signatures to test the model. Specifically, we look at how the GC mass function and surface density profile change with time by fitting a power law to each distribution. By comparing these distributions with related observable quantities such as the luminosity function and the observed surface density profile, we can begin to evaluate the model at past epochs.

We investigate the radial dust distribution in the protoplanetary disk of PDS 70 using multi-component spectral energy distribution (SED) modeling. By combining infrared spectra from Spitzer IRS and JWST MIRI with photometric data, we constrain emission from the inner wall and optically thin disk regions. While IRS data is well fit by a two-component model, MIRI requires additional components, revealing increased radial complexity in the dust distribution, consistent with dust transport processes such as radial drift and other mechanisms shaping the inner disk structure.

Mrk 1310 is a nearby Seyfert-1 galaxy that has received little attention in the UV and X-ray bands. We report on a systematic examination of optical, UV, and X-ray monitoring observations taken with the Neil Gehrels Swift Observatory, and pointed X-ray observations made with Chandra, NuSTAR, and XMM-Newton. We find that the UV and X-ray flux is variable by a factor of a few on time scales of just days. This remarkable behavior suggests that Mrk 1310 may harbor a changing-look active galactic nucleus (CLAGN). The pointed X-ray observations reveal fluxes that span 1.5 orders of magnitude over two decades. Over this time, weak, putative Fe K alpha emission lines appear to vary in centroid energy, often displaying red-shifts. We discuss our findings in the context of the growing diversity of behaviors observed in AGN.

In 2018, the NIRSPEC (Near Infrared Spectrometer) instrument on the Keck II telescope underwent a major upgrade, transitioning from NIRSPEC-1 to a modernized system (NIRSPEC-2). Following this upgrade, data reduction pipelines were optimized for post-upgrade observations and rely on structural assumptions that are often not satisfied by older datasets. As a result, archival NIRSPEC-1 observations are frequently incompatible with modern reduction methods. In this work, a modern high-resolution NIRSPEC reduction pipeline is adapted to process pre-modernization data and recover usable spectra from archival observations that would otherwise fail under standard procedures. The pipeline modifications accommodate irregularities in older datasets, including data-driven classification of non-standard nodding patterns, adjustments to trace-fitting procedures, and handling inconsistent or poorly recorded spectral orders. The modified pipeline successfully processes archival data through key reduction stages, including background subtraction, flat-fielding, trace identification, wavelength calibration, and spectral extraction. These results demonstrate that modern reduction tools can be extended to recover scientifically useful products from archival datasets, enabling continued use of archival NIRSPEC-1 observations for analysis.

Most of the hot baryons in the Universe are theorized to lie in filaments of matter that drain into galaxy clusters. Filament gas can reach temperatures high enough to scatter photons from the Cosmic Microwave Background, known as the thermal Sunyaev-Zel’dovich (SZ) effect, but filament SZ signal is faint and greatly obscured by noise. We aim to extract the SZ signal from a well-studied filament Northeast of the Coma Cluster using the all-sky Planck SZ map. SDSS galaxies within a redshift range around Coma of 0.019<z<0.029 trace this filament’s structure, which we use to isolate the SZ signal by subtracting background variation around the filament. For the first time, we detect a continuous signal from the Northeast filament extending to ~17 Mpc from the center of Coma with an average FWHM width of 0.8 Mpc. Statistical tests and comparison to nearby blank fields confirm the presence of this filament. We calculate a filament mass of 1.2 x 10^14 M_solar assuming a gas temperature of 3 x10^6 K. The total filament mass is an order of magnitude larger than the summed mass of each galaxy within the filament, which implies that SZ contributions are primarily from gas rather than individual galaxies. These observational results can help constrain gas characteristics in filament simulations.

The JWST MIRI detector exhibits a flux deficit persistence, but its timescales and impacts remain largely uncharacterized, particularly at the longest imaging wavelengths. In this study, we analyze full-field MIRI imager observations at 21 μm (F2100W) to quantify detector persistence following a saturation event by a bright (K = 5.65 mag) nearby (8.12 ± 0.04 pc) mid M-dwarf star, IRAS 21500+5903. Unlike typical persistence that appears as excess flux, this effect presents as a flux deficit in pixels previously illuminated by the saturating or near saturating source. We measure persistence at two post-saturation epochs: shortly after saturation (11.6 minutes) and an hour later (1.39 hours). Immediately after the saturation event, we detect a persistence level of 1.69±0.10%. By fitting a Bayesian exponential decay model to the two epochs, we estimate that persistence decreases to one-tenth of its initial value after 5.16+1.49−0.94 hours. We examine the implications of persistence for MIRI high-contrast imaging using the imager (not coronagraphy). Specifically, we discuss how MIRI detector persistence can produce false-positive exoplanet signals in direct imaging surveys, as well as degrade PSF subtraction, particularly at small inner working angles. We also outline mitigation strategies to avoid these impacts in future observations.