Volume 541, May 2012
|Number of page(s)||5|
|Section||Stellar structure and evolution|
|Published online||04 May 2012|
Mean angular diameters, distances, and pulsation modes of the classical Cepheids FF Aquilae and T Vulpeculae
CHARA/FLUOR near-infrared interferometric observations
LESIA, Observatoire de Paris, CNRS UMR 8109, UPMC, Université Paris
5 place Jules Janssen,
2 European Southern Observatory, Alonso de Córdova 3107, Casilla 19001, Santiago 19, Chile
3 Center for High Angular Resolution Astronomy, Georgia State University, PO Box 3965, Atlanta, Georgia 30302-3965, USA
Received: 23 February 2012
Accepted: 21 March 2012
We report the first angular diameter measurements of two classical Cepheids, FF Aql and T Vul, that we obtain using observations with the FLUOR instrument installed at the CHARA interferometric array. We derive average limb-darkened angular diameters of θLD = 0.878 ± 0.013 mas and θLD = 0.629 ± 0.013 mas, respectively, for FF Aql and T Vul. Combining these angular diameters with the HST-FGS trigonometric parallaxes leads to linear radii R = 33.6 ± 2.2 R⊙ and R = 35.6 ± 4.4 R⊙, respectively. The comparison with empirical and theoretical period–radius relations leads to the conclusion that these Cepheids are pulsating in their fundamental mode. The knowledge of this pulsation mode is of prime importance to calibrating the period–luminosity relation with a uniform sample of fundamental mode Cepheids.
Key words: techniques: interferometric / techniques: high angular resolution / stars: variables: Cepheids / stars: distances / stars: oscillations
© ESO, 2012
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