Year: 2018
Type: article
Abstract: We gathered more than 1130 high-resolution optical spectra for more than 250 Galactic classical Cepheids. The spectra were collected with the optical spectrographs UVES at VLT, HARPS at 3.6 m, FEROS at 2.2 m MPG/ESO, and STELLA. To improve the effective temperature estimates, we present more than 150 new line depth ratio (LDR) calibrations that together with similar calibrations already available in the literature allowed us to cover a broad range in wavelength (5348 ≤ λ ≤ 8427 Å) and in effective temperature (3500 ≤ Teff ≤ 7700 K). This gives us the unique opportunity to cover both the hottest and coolest phases along the Cepheid pulsation cycle and to limit the intrinsic error on individual measurements at the level of ~100 K. As a consequence of the high signal-to-noise ratio of individual spectra, we identified and measured hundreds of neutral and ionized lines of heavy elements, and in turn, have the opportunity to trace the variation of both surface gravity and microturbulent velocity along the pulsation cycle. The accuracy of the physical parameters and the number of Fe I (more than one hundred) and Fe II (more than ten) lines measured allowed us to estimate mean iron abundances with a precision better than 0.1 dex. We focus on 14 calibrating Cepheids for which the current spectra cover either the entire or a significant portion of the pulsation cycle. The current estimates of the variation of the physical parameters along the pulsation cycle and of the iron abundances agree very well with similar estimates available in the literature. Independent homogeneous estimates of both physical parameters and metal abundances based on different approaches that can constrain possible systematics are highly encouraged.
Source: Astronomy and Astrophysics
Authors: B. Proxauf, R. da Silva, V. V. Kovtyukh, G. Bono, L. Inno, B. Lemasle, J. Pritchard, N. Przybilla, J. Storm, M. A. Urbaneja, E. Valenti, M. Bergemann, R. Buonanno, V. D’Orazi, M. Fabrizio, I. Ferraro, G. Fiorentino, P. François, G. Iannicola, C. D. Laney, R.-P. Kudritzki, N. Matsunaga, M. Nonino, F. Primas, M. Romaniello, F. Thévenin
Institutions: University of Rome Tor Vergata, Astronomical Observatory of Rome, Agenzia Spaziale Italiana, National Institute for Astrophysics, Odesa I. I. Mechnikov National University, Isaac Newton Institute, Max Planck Institute for Astronomy, Heidelberg University, European Southern Observatory, Universität Innsbruck, Leibniz Institute for Astrophysics Potsdam, Collurania Teramo Observatory, Osservatorio Astronomico di Padova, Monash University, Osservatorio astronomico di Bologna, Centre National de la Recherche Scientifique, Observatoire de Paris, Galaxies, Etoiles, Physique et Instrumentation, Université Paris Diderot, Université de Picardie Jules Verne, Brigham Young University, South African Astronomical Observatory, University of Hawaiʻi at Mānoa, University of Hawaii System, Max Planck Institute for Astrophysics, Ludwig-Maximilians-Universität München, The University of Tokyo, Trieste Astronomical Observatory, Lagrange Laboratory, Observatoire de la Côte d’Azur
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
OpenAlex ID: W2799080579