9 papers
3D Non-LTE radiation transfer: theory and applications to stars, exoplanets, and kilonovae
Maria Bergemann, Richard Hoppe
Most of the physical information about astrophysical objects is obtained via the analysis of their electromagnetic spectra. Observed data coupled with radiation transfer models in…
Observational constraints on the origin of the elements. X. Combining NLTE and machine learning for chemical diagnostics of 4 million stars in the 4MIDABLE-HR survey
Nicholas Storm, Maria Bergemann, Tomasz RóżaÅski +9
We present the 4MOST-HR resolution Non-Local Thermal Equilibrium (NLTE) Payne artificial neural network (ANN), trained on new FGK spectra with 16 elements computed in NL…
A method to derive self-consistent NLTE astrophysical parameters for 4 million high-resolution 4MOST stellar spectra in half a day with invertible neural networks
Victor F. Ksoll, Nicholas Storm, Maria Bergemann +5
Modern spectroscopic surveys obtain spectra for millions of stars. However, classical spectroscopic methods can often be computationally expensive, rendering them impractical for t…
Solar carbon abundance from 3D non-LTE modelling of the diagnostic lines of the CH molecule
Richard Hoppe, Maria Bergemann, Philipp Eitner +5
The spectral lines of the CH molecule are a key carbon (C) abundance diagnostic in FGKM-type stars. These lines are detectable in metal-rich and, in contrast to atomic C lines, als…
On the Use of Field RR Lyrae as Galactic Probes -- VIII. Early Formation of the Galactic Spheroid
G. Bono, V. F. Braga, M. Fabrizio +54
We introduce a new photometric catalog of RR Lyrae variables (RRLs, 300,000) mainly based on data available in public datasets. We also present the largest and most homogeneo…
Testing stellar yield prescriptions in OMEGA+: Implications for rising sodium abundances in young thick disc stars
Evans K. Owusu, Ashley J. Ruiter, Alex J. Kemp +8
We recently identified an upturn in [Na/Fe] for the population of Solar-type stars in the Galactic young thick disc () at super-Solar metallicity in…