The atmosphere, the p-factor and the bright visible circumstellar environment of the prototype of classical Cepheids δ Cep

Journal
Date Issued
2017
Author(s)
Nardetto, Nicolas
•
•
Mérand, Antoine
•
Anderson, Richard I.
•
Fokin, Andrei
•
Fouqué, Pascal
•
Gallenne, Alexandre
•
Gieren, Wolfgang
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Graczyk, Dariusz
•
Kervella, Pierre
•
Mathias, Philippe
•
Mourard, Denis
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Neilson, Hilding
•
Pietrzynski, Grzegorz
•
Pilecki, Bogumil
•
•
Storm, Jesper
DOI
Abstract
Even ≃ 16000 cycles after its discovery by John Goodricke in 1783, δ Cep, the prototype of classical Cepheids, is still studied intensively in order to better understand its atmospheric dynamical structure and its environment. Using HARPS-N spectroscopic measurements, we have measured the atmospheric velocity gradient of δ Cep for the first time and we confirm the decomposition of the projection factor, a subtle physical quantity limiting the Baade-Wesselink (BW) method of distance determination. This decomposition clarifies the physics behind the projection factor and will be useful to interpret the hundreds of p-factors that will come out from the next Gaia release. Besides, VEGA/CHARA interferometric observations of the star revealed a bright visible circumstellar environment contributing to about 7% to the total flux. Better understanding the physics of the pulsation and the environment of Cepheids is necessary to improve the BW method of distance determination, a robust tool to reach Cepheids in the MilkyWay, and beyond, in the Local Group.
Coverage
Wide-Field Variability Surveys: A 21st Century Perspective – 22nd Los Alamos Stellar Pulsation
All editors
Catelan, M.; Gieren, W.
Volume
152
Start page
07003
Conferenece
Wide-Field Variability Surveys: A 21st Century Perspective – 22nd Los Alamos Stellar Pulsation – Conference Series Meeting
Conferenece place
San Pedro de Atacama, Chile
Conferenece date
November 28 – December 2, 2016
Uri
Url
Issn Identifier
2101-6275
Ads BibCode
2017EPJWC.15207003N
Rights
open.access
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