Issue |
A&A
Volume 656, December 2021
|
|
---|---|---|
Article Number | A102 | |
Number of page(s) | 23 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361/202141680 | |
Published online | 08 December 2021 |
Inspecting the Cepheid parallax of pulsation using Gaia EDR3 parallaxes
Projection factor and period-luminosity and period-radius relations
1
LESIA, Observatoire de Paris, Université PSL, CNRS, Sorbonne Université, Université de Paris, 5 place Jules Janssen, 92195 Meudon, France
2
Université Paris-Saclay, CNRS, Institut d’Astrophysique Spatiale, 91405 Orsay, France
e-mail: boris.trahin@ias.u-psud.fr
3
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
4
Université Côte d’Azur, Observatoire de la Côte d’Azur, CNRS, Laboratoire Lagrange, France
5
Nicolaus Copernicus Astronomical Center of the Polish Academy of Sciences, ul. Bartycka 18, 00-716 Warszawa, Poland
6
Universidad de Concepción, Departamento de Astronomía, Casilla 160-C Concepción, Chile
7
Unidad Mixta Internacional Franco-Chilena de Astronomia (CNRS UMI 3386), Departamento de Astronomía, Universidad de Chile, Camino el Observatorio 1515, Las Condes, Santiago, Chile
Received:
30
June
2021
Accepted:
30
August
2021
Context. As primary anchors of the distance scale, Cepheid stars play a crucial role in our understanding of the distance scale of the Universe because of their period-luminosity relation. Determining precise and consistent parameters (radius, temperature, color excess, and projection factor) of Cepheid pulsating stars is therefore very important.
Aims. With the high-precision parallaxes delivered by the early third Gaia data release (EDR3), we aim to derive various parameters of Cepheid stars in order to calibrate the period-luminosity and period-radius relations and to investigate the relation of period to p-factor.
Methods. We applied an implementation of the parallax-of-pulsation method through the algorithm called spectro-photo-interferometry of pulsating stars (SPIPS), which combines all types of available data for a variable star (multiband and multicolor photometry, radial velocity, effective temperature, and interferometry measurements) in a global modeling of its pulsation.
Results. We present the SPIPS modeling of a sample of 63 Galactic Cepheids. Adopting Gaia EDR3 parallaxes as an input associated with the best available dataset, we derive consistent values of parameters for these stars such as the radius, multiband apparent magnitudes, effective temperatures, color excesses, period changes, Fourier parameters, and the projection factor.
Conclusions. Using the best set of data and the most precise distances for Milky Way Cepheids, we derive new calibrations of the period-luminosity and period-radius relations: MKS = −5.529±0.015 − 3.141±0.050(log P − 0.9) and log R = 1.763±0.003 + 0.653±0.012(log P − 0.9). After investigating the dependences of the projection factor on the parameters of the stars, we find a high dispersion of its values and no evidence of its correlation with the period or with any other parameters such as radial velocity, temperature, or metallicity. Statistically, the p-factor has an average value of p = 1.26 ± 0.07, but with an unsatisfactory agreement (σ = 0.15). In absence of any clear correlation between the p-factor and other quantities, the best agreement is obtained under the assumption that the p-factor can take any value in a band with a width of 0.15. This result highlights the need for a further examination of the physics behind the p-factor.
Key words: stars: variables: Cepheids / stars: fundamental parameters / distance scale
© B. Trahin et al. 2021
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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