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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2005

The projection factor of delta Cephei. A calibration of the Baade-Wesselink method using the CHARA Array

Résumé

Cepheids play a key role in astronomy as standard candles for measuring intergalactic distances. Their distance is usually inferred from the period-luminosity relationship, calibrated using the semi-empirical Baade-Wesselink method. Using this method, the distance is known to a multiplicative factor, called the projection factor. Presently, this factor is computed using numerical models - it has hitherto never been measured directly. Based on our new interferometric measurements obtained with the CHARA Array and the already published parallax, we present a geometrical measurement of the projection factor of a Cepheid, delta Cep. The value we determined, p=1.27 ± 0.06, confirms the generally adopted value of p=1.36 within 1.5 sigmas. Our value is in line with recent theoretical predictions of Nardetto et al. (2004, A&A, 428, 131).
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Dates et versions

hal-03797207 , version 1 (04-10-2022)

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Antoine Merand, Pierre Kervella, Vincent Coudé Du Foresto, Stephen Ridgway, Jason Aufdenberg, et al.. The projection factor of delta Cephei. A calibration of the Baade-Wesselink method using the CHARA Array. Astronomy and Astrophysics - A&A, 2005, 438, pp.L9-L12. ⟨10.1051/0004-6361:200500139⟩. ⟨hal-03797207⟩
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