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Dynamical substructures of local metal-poor halo
Shi, Jianrong; Ma, Jun; Ye, Dashuang +1 more
Based on 4098 very metal poor (VMP) stars with six-dimensional phase-space and chemical information from Gaia Data Release 3 (DR3) and Large sky Area Multi-Object fiber Spectroscopic Telescope DR9 as tracers, we apply an unsupervised machine learning algorithm, shared nearest neighbour, to identify stellar groups in the action-energy (J-E) space. …
Fast Outflows and Luminous He II Emission in Dwarf Galaxies with Active Galactic Nuclei (AGN)
Tripp, Todd M.; Hamann, Fred; Veilleux, Sylvain +6 more
While stellar processes are believed to be the main source of feedback in dwarf galaxies, the accumulating discoveries of active galactic nuclei (AGN) in dwarf galaxies over recent years arouse the interest to also consider AGN feedback in them. Fast, AGN-driven outflows, a major mechanism of AGN feedback, have indeed been discovered in dwarf gala…
BOWIE-ALIGN: A JWST comparative survey of aligned versus misaligned hot Jupiters to test the dependence of atmospheric composition on migration history
Owen, James E.; Kirk, James; López-Morales, Mercedes +20 more
A primary objective of exoplanet atmosphere characterization is to learn about planet formation and evolution, however, this is challenged by degeneracies. To determine whether differences in atmospheric composition can be reliably traced to differences in evolution, we are undertaking a transmission spectroscopy survey with JWST to compare the co…
The GALAH survey: elemental abundances in open clusters using joint effective temperature and surface gravity photometric priors
Lewis, Geraint F.; Buder, Sven; Bland-Hawthorn, Joss +10 more
The ability to measure precise and accurate stellar effective temperatures (Teff) and surface gravities (log (g)) is essential in determining accurate and precise abundances of chemical elements in stars. Measuring log (g) from isochrones fitted to colour-magnitude diagrams of open clusters is significantly more accurate and precise com…
VLA FRAMEx. I. Wideband Radio Properties of the AGN in NGC 4388
Fischer, Travis C.; Secrest, Nathan J.; Johnson, Megan C. +5 more
We present the first results from Karl G. Jansky Very Large Array (VLA) observations as a part of the Fundamental Reference Active Galactic Nucleus (AGN) Monitoring Experiment, a program to understand the relationship between AGN accretion physics and wavelength-dependent position as a function of time. With this VLA survey, we investigate the rad…
Diurnal Ejection of Boulder Clusters on Comet 67P Lasting beyond 3 au
Keller, Horst Uwe; Shi, Xian; Güttler, Carsten +6 more
Ejection of large boulder-like debris is a vigorous form of cometary activity that is unlikely induced by water ice out-gassing alone but rather associated with the sublimation of super-volatile ices. Though perceived on several comets, the actual pattern and mechanism of such activity are still unclear. Here we report on a specialized observation…
Next-generation Accretion Disk Reflection Model: High-density Plasma Effects
Kallman, Timothy R.; Bautista, Manuel; Harrison, Fiona A. +5 more
Luminous accretion disks around black holes are expected to have densities of ∼1015‑1022 cm‑3, which are high enough that plasma physics effects become important. Many of these effects have been traditionally neglected in the calculation of atomic parameters, and therefore in photoionization models and ultimately a…
TDCOSMO: XVI. Measurement of the Hubble constant from the lensed quasar WGD 2038–4008
Treu, Tommaso; Marshall, Philip J.; Fassnacht, Christopher D. +17 more
Time-delay cosmography is a powerful technique to constrain cosmological parameters, particularly the Hubble constant (H0). The TDCOSMO Collaboration is performing an ongoing analysis of lensed quasars to constrain cosmology using this method. In this work, we obtain constraints from the lensed quasar WGD 2038‑4008 using new time-delay …
Artificial Intelligence Assisted Inversion (AIAI): Quantifying the Spectral Features of 56Ni of Type Ia Supernovae
Wang, Lifan; Hu, Lei; Brown, Peter J. +1 more
Following our previous study of Artificial Intelligence Assisted Inversion (AIAI) of supernova analyses, we train a set of deep neural networks based on the 1D radiative transfer code TARDIS to simulate the optical spectra of Type Ia supernovae (SNe Ia) between 10 and 40 days after the explosion. The neural networks are applied to derive the mass …
Photometry of Saturated Stars with Neural Networks
Kochanek, Christopher S.; Winecki, Dominik
We use a multilevel perceptron (MLP) neural network to obtain photometry of saturated stars in the All-Sky Automated Survey for Supernovae (ASAS-SN). The MLP can obtain fairly unbiased photometry for stars from g ≃ 4 to 14 mag, particularly compared to the dispersion (15%–85% 1σ range around the median) of 0.12 mag for saturated (g < 11.5 mag) …