相关论文: NEBULAR: A simple synthesis code for the hydrogen …
Inferring stellar parameters and chemical abundances by forward modeling stellar spectra usually requires a spectral synthesis code, or an emulator constructed from a curated training set. In these situations continuum normalization is…
Nebular emission lines are critical to measure physical properties in the ionized gas (e.g., metallicity, the SFR, or dust attenuation). They also account for a significant fraction of broadband fluxes, in particular at the highest…
Stellar spectra are often modeled and fit by interpolating within a rectilinear grid of synthetic spectra to derive the stars' labels: stellar parameters and elemental abundances. However, the number of synthetic spectra needed for a…
The sheer interstellar abundance of helium makes any bound molecules or complexes containing it of potential interest for astrophysical observation. This work utilizes high-level and trusted quantum chemical techniques to predict the…
A novel approach is presented for the solution of instantaneous chemical equilibrium problems. The chemical equilibrium can be considered, due to its intrinsically local character, as a mapping of the three-dimensional parameter space…
We present new calculations of Stark broadened profiles for neutral helium lines using computer simulations that include some important aspects aimed at better representing the dynamical environment of the helium atom. These include the…
Whenever observations are compared to theories, an estimate of the uncertainties associated with the observations is vital if the comparison is to be meaningful. However, many determinations of temperatures, densities and abundances in…
Excalibur is a non-parametric, hierarchical framework for precision wavelength-calibration of spectrographs. It is designed with the needs of extreme-precision radial velocity (EPRV) in mind, which require that instruments be calibrated or…
Improving the interpretability of deep neural networks has recently gained increased attention, especially when the power of deep learning is leveraged to solve problems in physics. Interpretability helps us understand a model's ability to…
Models of stellar spectra are necessary for interpreting light from individual stars, planets, integrated stellar populations, nebulae, and the interstellar medium. We provide a comprehensive and homogeneous collection of synthetic spectra…
Clustering of large-scale structure provides significant cosmological information through the power spectrum of density perturbations. Additional information can be gained from higher-order statistics like the bispectrum, especially to…
High spectral resolution spectroscopy has proved to be very useful for the advancement of chemical abundances studies in photoionized nebulae, such as H II regions and planetary nebulae (PNe). Classical analyses make use of the intensity of…
Linear nanotubular boron-carbon heterojunctions are systematically constructed and studied with the help of ab initio total energy calculations. The structural compatibility of the two classes of materials is shown, and a simple recipe that…
The cosmic abundance of the 3-He isotope has important implications for many fields of astrophysics. We are using the 8.665 GHz hyperfine transition of 3-He+ to determine the 3-He/H abundance in Milky Way HII regions and planetary nebulae.…
Near-infrared (2.5-5.0$\,\mu$m) low-resolution ($\lambda/\Delta\lambda{\sim}100$) spectra of 72 Galactic planetary nebulae (PNe) were obtained with the Infrared Camera (IRC) in the post-helium phase. The IRC, equipped with a $1'{\times}1'$…
The Cesam code is a consistent set of programs and routines which perform calculations of 1D quasi-hydrostatic stellar evolution including microscopic diffusion of chemical species and diffusion of angular momentum. The solution of the…
Star-forming galaxies with nebular HeII emission contain very energetic ionizing sources of radiation, which can be considered as analogs to the major contributors of the reionization of the Universe in early epochs. It is therefore of…
We present a detailed comparison of optical H II region spectra to photoionization models based on modern stellar atmosphere models. We examine both spatially resolved and integrated emission-line spectra of the HII regions DEM L323, DEM…
Deep spectroscopy of the planetary nebula (PN) NGC\,6153 shows that its heavy element abundances derived from optical recombination lines (ORLs) are ten times higher than those derived from collisionally excited lines (CELs), and points to…
Imidogen (NH) is a reactive molecule whose presence in astrochemical environments is of interest due to its role in the formation of nitrogen-containing molecules and as a potential probe of nitrogen abundance. Spectroscopic NH monitoring…