http://arxiv.org/abs/2208.09403
We have conducted a search for open clusters in the vicinity of Galactic classical Cepheids based on high-quality astrometry from the ESA mission Gaia’s third data release (DR3) to improve the calibration of the Leavitt law. Our approach requires no prior knowledge of existing clusters, allowing us to both detect new host clusters and cross-check previously reported associations. Our Gold sample consists of 34 Cepheids residing in 28 open clusters, including 27 fundamental mode and 7 overtone Cepheids. Three new bona fide cluster Cepheids are reported (V0378 Cen, ST Tau and GH Lup) and the host cluster identifications for VW Cru, IQ Nor and SX Vel is corrected. The fraction of Cepheids occurring in open clusters within 2 kpc of the Sun is $f_{\mathrm{CC,2kpc}}=0.092 \pm 0.009$. Combining cluster and field Cepheids, we calibrate the Galactic Cepheid Leavitt law for a variety of individual optical and near-infrared passbands, as well as using reddening-free Wesenheit magnitudes based on Gaia and HST photometry, while solving for the residual offset applicable to Cepheid parallaxes, $\Delta \varpi_{\text{Cep}}$. The most direct comparison of our results with the SH0ES distance ladder yields excellent ($0.3\sigma$) agreement for both the absolute magnitude of a 10 d Solar metallicity Cepheid in the NIR HST Wesenheit magnitudes, $M_H^W=-5.915\pm0.017$ mag, and the residual parallax offset, $\varpi_{\text{Cl}}=-13\pm5\,\mu$as. Using 26 cluster Cepheids and 225 MW Cepheids with Gaia DR3 astrometry and photometry, we determine the absolute magnitude of a 10 d fundamental mode Cepheid in the Gaia Wesenheit magnitude at Solar metallicity $M_G^W =-5.996\pm 0.019$ mag and $\Delta \varpi_{\text{Cep}}=-19 \pm 3\,\mu$as. These results mark the currently most accurate absolute calibrations of the Cepheid luminosity scale based purely on observations of MW Cepheids.
M. Reyes and R. Anderson
Mon, 22 Aug 22
48/53
Comments: 23 pages,comments welcome
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