Browsing by Author "Breuval, Louise"

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    An Absolute Calibration of the Near-infrared Period-Luminosity Relations of Type II Cepheids in the Milky Way and in the Large Magellanic Cloud
    (London : Institute of Physics Publ., 2022) Wielgórski, Piotr; Pietrzyński, Grzegorz; Pilecki, Bogumił; Gieren, Wolfgang; Zgirski, Bartłomiej; Górski, Marek; Hajdu, Gergely; Narloch, Weronika; Karczmarek, Paulina; Smolec, Radosław; Kervella, Pierre; Storm, Jesper; Gallenne, Alexandre; Breuval, Louise; Lewis, Megan; Kałuszyński, Mikołaj; Graczyk, Dariusz; Pych, Wojciech; Suchomska, Ksenia; Taormina, Mónica; Rojas Garcia, Gonzalo; Kotek, Aleksandra; Chini, Rolf; Pozo Nũnez, Francisco; Noroozi, Sadegh; Sobrino Figaredo, Catalina; Haas, Martin; Hodapp, Klaus; Mikołajczyk, Przemysław; Kotysz, Krzysztof; Moździerski, Dawid; Kołaczek-Szymański, Piotr
    We present time-series photometry of 21 nearby type II Cepheids in the near-infrared J, H, and K s passbands. We use this photometry, together with the Third Gaia Early Data Release parallaxes, to determine for the first time period-luminosity relations (PLRs) for type II Cepheids from field representatives of these old pulsating stars in the near-infrared regime. We found PLRs to be very narrow for BL Herculis stars, which makes them candidates for precision distance indicators. We then use archival photometry and the most accurate distance obtained from eclipsing binaries to recalibrate PLRs for type II Cepheids in the Large Magellanic Cloud (LMC). Slopes of our PLRs in the Milky Way and in the LMC differ by slightly more than 2σ and are in a good agreement with previous studies of the LMC, Galactic bulge, and Galactic globular cluster type II Cepheids samples. We use PLRs of Milky Way type II Cepheids to measure the distance to the LMC, and we obtain a distance modulus of 18.540 ± 0.026(stat.) ± 0.034(syst.) mag in the W JK Wesenheit index. We also investigate the metallicity effect within our Milky Way sample, and we find a rather significant value of about -0.2 mag dex-1 in each band meaning that more metal-rich type II Cepheids are intrinsically brighter than their more metal-poor counterparts, in agreement with the value obtained from type II Cepheids in Galactic globular clusters. The main source of systematic error on our Milky Way PLRs calibration, and the LMC distance, is the current uncertainty of the Gaia parallax zero-point.
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    The Milky Way Cepheid Leavitt law based on Gaia DR2 parallaxes of companion stars and host open cluster populations
    (Les Ulis : EDP Sciences, 2020) Breuval, Louise; Kervella, Pierre; Anderson, Richard I.; Riess, Adam G.; Arenou, Frédéric; Trahin, Boris; Mérand, Antoine; Gallenne, Alexandre; Gieren, Wolfgang; Storm, Jesper; Bono, Giuseppe; Pietrzynski, Grzegorz; Nardetto, Nicolas; Javanmardi, Behnam; Hocdé, Vincent
    Aims. Classical Cepheids provide the foundation for the empirical extragalactic distance ladder. Milky Way Cepheids are the only stars in this class accessible to trigonometric parallax measurements. However, the parallaxes of Cepheids from the second Gaia data release (GDR2) are affected by systematics because of the absence of chromaticity correction, and occasionally by saturation. Methods. As a proxy for the parallaxes of 36 Galactic Cepheids, we adopt either the GDR2 parallaxes of their spatially resolved companions or the GDR2 parallax of their host open cluster. This novel approach allows us to bypass the systematics on the GDR2 Cepheids parallaxes that is induced by saturation and variability. We adopt a GDR2 parallax zero-point (ZP) of −0.046 mas with an uncertainty of 0.015 mas that covers most of the recent estimates. Results. We present new Galactic calibrations of the Leavitt law in the V, J, H, KS, and Wesenheit WH bands. We compare our results with previous calibrations based on non-Gaia measurements and compute a revised value for the Hubble constant anchored to Milky Way Cepheids. Conclusions. From an initial Hubble constant of 76.18 ± 2.37 km s−1 Mpc−1 based on parallax measurements without Gaia, we derive a revised value by adopting companion and average cluster parallaxes in place of direct Cepheid parallaxes, and we find H0 = 72.8 ± 1.9 (statistical + systematics) ±1.9 (ZP) km s−1 Mpc−1 when all Cepheids are considered and H0 = 73.0 ± 1.9 (statistical + systematics) ±1.9 (ZP) km s−1 Mpc−1 for fundamental mode pulsators only.