Search Publications
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) …
Combined Gemini-South and HST photometric analysis of the globular cluster NGC 6558: The age of the metal-poor population of the Galactic bulge
Bica, E.; Nardiello, D.; Barbuy, B. +8 more
Context. NGC 6558 is a low-galactic-latitude globular cluster projected in the direction of the Galactic bulge. Due to high reddening, this region presents challenges in deriving accurate parameters, which require meticulous photometric analysis. We present a combined analysis of near-infrared and optical photometry from multi-epoch high-resolutio…
From gas to stars: MUSEings on the internal evolution of IC 1613
Iorio, G.; Kacharov, N.; Skillman, E. D. +9 more
Context. The kinematics and chemical composition of stellar populations of different ages provide crucial information on the evolution of the various components of a galaxy. Aim. Our aim is to determine the kinematics of individual stars as a function of age in IC 1613, a star-forming, gas-rich, and isolated dwarf galaxy of the Local Group (LG). M…
The acoustic size of the Sun
Gough, D. O.; Takata, M.
Analysis of f-mode frequencies has provided a measure of the radius of the Sun which is lower, by a few hundredths per cent, than the photospheric radius determined by direct optical measurement. Part of this difference can be understood by recognizing that it is primarily the variation of density well beneath the photosphere of the star that dete…