The Pulsation Mode and Distance of the Cepheid FF Aquilae
Abstract
The determination of pulsation mode and distance for field Cepheids is a complicated problem best resolved by a luminosity estimate. For illustration a technique based on spectroscopic luminosity discrimination is applied to the 4.47d s-Cepheid FF Aql. Line ratios in high dispersion spectra of the variable yield values of <Mv>=-3.40+-0.02 s.e.(+-0.04 s.d.), average effective temperature Teff=6195+-24 K, and intrinsic color (<B>-<V>)o = +0.506+-0.007, corresponding to a reddening of E(B-V)=0.25+-0.01, or E(B-V)(B0)=0.26+-0.01. The skewed light curve, intrinsic color, and luminosity of FF Aql are consistent with fundamental mode pulsation for a small amplitude classical Cepheid on the blue side of the instability strip, not a sinusoidal pulsator. A distance of 413+-14 pc is estimated from the Cepheid's angular diameter in conjunction with a mean radius of <R>=39.0+-0.7 Rsun inferred from its luminosity and effective temperature. The dust extinction towards FF Aql is described by a ratio of total-to-selective extinction of Rv=Av/E(B-V)=3.16+-0.34 according to the star's apparent distance modulus.
Keywords
Cite
@article{arxiv.1306.1228,
title = {The Pulsation Mode and Distance of the Cepheid FF Aquilae},
author = {D. G. Turner and V. V. Kovtyukh and R. E. Luck and L. N. Berdnikov},
journal= {arXiv preprint arXiv:1306.1228},
year = {2015}
}
Comments
To appear in ApJL