Intensity interferometry of P Cygni in the H$\alpha$ emission line: towards distance calibration of LBV supergiant stars

Abstract

We present intensity interferometry of the luminous blue variable P Cyg in the light of its H$\alpha$ emission performed with 1\,m-class telescopes. We compare the measured visibility points to synthesized interferometric data based on the CMFGEN physical modeling of a high-resolution spectrum of P Cyg recorded almost simultaneously with our interferometry data. Tuning the stellar parameters of P Cyg and its H$\alpha$ linear diameter we estimate the distance of P Cyg as $1.56\pm 0.25$~kpc, which is compatible within $1\sigma$ with $1.36\pm 0.24$~kpc reported by the Gaia DR2 catalogue of parallaxes recently published. Both values are significantly smaller than the canonic value of $1.80\pm 0.10$~kpc usually adopted in literature. Our method used to calibrate the distance of P Cyg can apply to very massive and luminous stars both in our galaxy and neighbour galaxies and can improve the so-called Wind-Momentum Luminosity relation that potentially applies to calibrate cosmological candles in the local Universe.

To be published in MNRAS

References in corpus (4)

• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• Near-Infrared interferometry of Eta Carinae with high spatial and spectral resolution using the VLTI and the AMBER instrument
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• Observations with the Southern Connecticut Stellar Interferometer. I. Instrument Description and First Results
• I3T: Intensity Interferometry Imaging Telescope
• Comparing Different Approaches for Stellar Intensity Interferometry
• Investigating the accuracy achievable in reconstructing the angular sizes of stars through stellar intensity interferometry observations