Interstellar extinction of classical Cepheids from neighboring stars I. Methodology and application to 16 Galactic Cepheids
Abstract
Galactic Cepheid variable stars are fundamental calibrators of the cosmic distance scale through their Period-Luminosity (PL) relation. The high-precision parallaxes expected from Gaia Data Release 4 (DR4) will enable a calibration of the Milky Way PL relation with unprecedented precision. This will place stringent requirements on interstellar extinction corrections, which remain a dominant source of uncertainty. We strive to derive highly accurate extinction values for Galactic Cepheids. We present an innovative methodology relying on the analysis of neighboring field stars and apply it to a pilot sample of 16 Cepheids. We identify physically near field stars using Gaia DR3 astrometry. For these stars, we determine atmospheric parameters from medium- to high-resolution VLT/FLAMES spectroscopy. Fixing these parameters, we derive individual extinctions by fitting spectral energy distributions constructed from Gaia XP spectra and infrared photometry. We then reconstruct the three-dimensional distribution of extinction and interpolate extinction to the Cepheid position. We report extinction Av, total-to-selective extinction ratio Rv, and color excess E(B-V) for all 16 Cepheids. Our method achieves a mean precision of approximately 5%, improving upon typical literature values, with no significant systematic offset detected. We demonstrate that using field stars bypasses uncertainties associated with Cepheid variability and can provide robust extinction estimates for Galactic Cepheids.
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BibTeX
@misc{kiviaho2026interstellar,
title = {{Interstellar extinction of classical Cepheids from neighboring stars I. Methodology and application to 16 Galactic Cepheids}},
author = {Wilma Kiviaho and Pierre Kervella and Mika Juvela and Alexandre Gallenne and Nicolas Nardetto and Carine Babusiaux and Rosine Lallement and Vincent Hocdé and Garance Bras and Nancy Remage Evans and Antoine Mérand and Grzegorz Pietrzyński and Gergely Hajdu and Henryka Netzel and Ricardo Salinas and Bogumił Pilecki and Cezary Gałan and Frédéric Arenou and Manon Bailleul and Katia Sivkova and Daniela González and Louise Breuval and Rajeev Singh Rathour and Brankica Apostolova},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.28406},
eprint = {2609.28406},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.28406},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Interstellar extinction of classical Cepheids from neighboring stars I. Methodology and application to 16 Galactic Cepheids
AU - Wilma Kiviaho
AU - Pierre Kervella
AU - Mika Juvela
AU - Alexandre Gallenne
AU - Nicolas Nardetto
AU - Carine Babusiaux
AU - Rosine Lallement
AU - Vincent Hocdé
AU - Garance Bras
AU - Nancy Remage Evans
AU - Antoine Mérand
AU - Grzegorz Pietrzyński
AU - Gergely Hajdu
AU - Henryka Netzel
AU - Ricardo Salinas
AU - Bogumił Pilecki
AU - Cezary Gałan
AU - Frédéric Arenou
AU - Manon Bailleul
AU - Katia Sivkova
AU - Daniela González
AU - Louise Breuval
AU - Rajeev Singh Rathour
AU - Brankica Apostolova
PY - 2026
DA - 2026/09/23
PB - arXiv
DO - 10.48550/arxiv.2609.28406
UR - https://arxiv.org/abs/2609.28406
AB - Galactic Cepheid variable stars are fundamental calibrators of the cosmic distance scale through their Period-Luminosity (PL) relation. The high-precision parallaxes expected from Gaia Data Release 4 (DR4) will enable a calibration of the Milky Way PL relation with unprecedented precision. This will place stringent requirements on interstellar extinction corrections, which remain a dominant source of uncertainty. We strive to derive highly accurate extinction values for Galactic Cepheids. We present an innovative methodology relying on the analysis of neighboring field stars and apply it to a pilot sample of 16 Cepheids. We identify physically near field stars using Gaia DR3 astrometry. For these stars, we determine atmospheric parameters from medium- to high-resolution VLT/FLAMES spectroscopy. Fixing these parameters, we derive individual extinctions by fitting spectral energy distributions constructed from Gaia XP spectra and infrared photometry. We then reconstruct the three-dimensional distribution of extinction and interpolate extinction to the Cepheid position. We report extinction Av, total-to-selective extinction ratio Rv, and color excess E(B-V) for all 16 Cepheids. Our method achieves a mean precision of approximately 5%, improving upon typical literature values, with no significant systematic offset detected. We demonstrate that using field stars bypasses uncertainties associated with Cepheid variability and can provide robust extinction estimates for Galactic Cepheids.
ER -