Modern stellar spectroscopy caveats

Abstract

Multiple codes are available to derive atmospheric parameters and individual chemical abundances from high-resolution spectra of AFGKM stars. Almost all spectroscopists have their own preferences regarding which code and method to use. But the intrinsic differences between codes and methods lead to complex systematics that depend on multiple variables such as the selected spectral regions and the radiative transfer code used. I expand iSpec, a popular open-source spectroscopic tool, to support the most well-known radiative transfer codes and assess their similarities and biases when using multiple set-ups based on the equivalent-width method and the synthetic spectral-fitting technique (interpolating from a pre-computed grid of spectra or synthesizing with interpolated model atmospheres). This work shows that systematic differences on atmospheric parameters and abundances between most of the codes can be reduced when using the same method and executing a careful spectral feature selection. However, it may not be possible to ignore the remaining differences, depending on the particular case and the required precision. Regarding methods, equivalent-width-based and spectrum-fitting analyses exhibit large differences that are caused by their intrinsic differences, which is significant given the popularity of these two methods. The results help to identify the key caveats of modern spectroscopy that all scientists should be aware of before trusting their own results or being tempted to combine atmospheric parameters and abundances from the literature.

accepted for publication in MNRAS (language corrections in v2)

References in corpus (39)

• Scikit-learn: Machine Learning in Python
• Astropy: A Community Python Package for Astronomy
• The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package
• A grid of MARCS model atmospheres for late-type stars I. Methods and general properties
• SDSS-III: Massive Spectroscopic Surveys of the Distant Universe, the Milky Way Galaxy, and Extra-Solar Planetary Systems
• The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
• Determining stellar atmospheric parameters and chemical abundances of FGK stars with iSpec
• ULySS: A Full Spectrum Fitting Package
• A Spectroscopic Study of the Ancient Milky Way: F- and G-Type Stars in the Third Data Release of the Sloan Digital Sky Survey
• The Cannon: A data-driven approach to stellar label determination
• Gaia FGK Benchmark Stars - Metallicity
• Gaia FGK Benchmark Stars: Effective temperatures and surface gravities
• Stellar Abundances in the Solar Neighborhood: The Hypatia Catalog
• Gaia-ESO Survey: The analysis of high-resolution UVES spectra of FGK-type stars
• Gaia FGK benchmark stars: abundances of alpha and iron-peak elements
• Automated derivation of stellar atmospheric parameters and chemical abundances: the MATISSE algorithm
• Detailed analysis of Balmer lines in cool dwarf stars
• The Gaia FGK Benchmark Stars - High resolution spectral library
• Constructing A Flexible Likelihood Function For Spectroscopic Inference
• Atomic and Molecular Data for Optical Stellar Spectroscopy
• Remarks on statistical errors in equivalent widths
• Accurate abundance analysis of late-type stars: advances in atomic physics
• High-precision stellar abundances of the elements - methods and applications
• GALA: an automatic tool for the abundance analysis of stellar spectra
• ZASPE: A Code to Measure Stellar Atmospheric Parameters and their Covariance from Spectra
• Gaia FGK Benchmark stars: Opening the black box of stellar element abundance determination
• A Comparison of Stellar Elemental Abundance Techniques and Measurements
• Identifying the best iron-peak and $\alpha$-capture elements for chemical tagging: The impact of the number of lines on measured scatter
• Geometry of giant star model atmospheres: A consistency test
• Testing the chemical tagging technique with open clusters
• Gaia FGK Benchmark Stars: New Candidates At Low-Metallicities
• The OCCASO survey: Presentation and radial velocities of twelve Milky Way Open Clusters
• OCCASO II. Physical parameters and Fe abundances of Red Clump stars in 18 Open Clusters
• Atmospheric stellar parameters for large surveys using FASMA, a new spectral synthesis package
• Some Aspects of the calculation of Balmer lines in the sun and stars
• A phylogenetic approach to chemical tagging. Reassembling open cluster stars
• Accurate effective temperature from H$\alpha$ profiles
• Sick, the spectroscopic inference crank
• How uncertainties on stellar atmospheric parameters impact exoplanet studies?

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